Intro
Aid in identifying
1. Dichotomous key (need citations)
2. Illustrations and photos (need citations)
3. Written descriptions (Smith, 1947)
Key out - how do we confirm our conclusion?
Inadequacy of Smith, 1947: New genera, changes in nomenclature, taxonomic changes, terminology
Effect of Bolton's classification
intro
Recognition:
Amblyopones commonly occur in wooded areas, especially those that are well shaded. They are subterranean foraging in the soil and leaf litter and are rarely seen on the surface of the ground. Some species show a preference for centipedes. Amblyopone is considered the most primitive and generalized genus in the Nearctic region. It is found throughout the USA except for the north central region, and in Canada it is found in the east. It is usually uncommon in drier habitats. There are three species.
Recognition: Total length 4-6.5 mm. Mandible long and linear; inner border with a row of coarse, bidenticulate teeth and a single, long, curved tooth at the apex. Mandible inserted at the anterolateral corner of the head. Clypeus with anterior border denticulate. Eye very small. Antenna 12 segmented; scape short. Petiole has distinct anterior and dorsal faces but lacks a posterior face since the attachment of the petiole to the gaster is broad and approximately the same height as the petiole; petiole and first gastral segment separated dorsally and laterally only by a constriction. Petiole with ventral tooth.
Similar Genera: Genus Prionopelta also has the petiole broadly attached to the gaster, but its mandibles are short and narrow with three teeth, and the mandibles can close tightly around the clypeus. Prionopelta is found only in southern Florida. Members of the genera Odontomachus and Anochetus also have long, linear mandibles. They can be easily distinguished from Amblyopone by: their mandibles have at their apex 2 0r 3 teeth arranged in a vertical series, mandible is inserted in the middle of the anterior margin of the head, clypeus not denticulate, and petiole scale-like and not broadly attached to the gaster. Both Odontomachus and Anochetus are found only in the southern USA.
This tropicopolitan genus of small, soil-inhabiting ants is most commonly found in moist tropical forests. One species extends into southern Florida. They are predators especially of small chilopods.
Recognition: Length about 2 mm. Mandibles short and narrow with 3 apical teeth, and the mandibles close tightly around clypeus. Mandibles inserted at anterolateral corner of head. Eye very small. Antenna 12 segmented, the apical 3-4 segments enlarged and forming an indistinct club. The petiole is thick, low, and rectangular. Petiole has distinct anterior and dorsal faces but lacks a posterior face since the attachment of the petiole to the gaster is broad and approximately the same height as the petiole; petiole and first gastral segment separated dorsally and laterally only by a constriction.
Similar Genera: The broad attachment of the petiole to the gaster separates Prionopelta from all Nearctic genera except Amblyopone. Genus Amblyopone also has its petiole broadly attached to the gaster, but the mandibles are long and straight with coarse bidentate teeth along the inner margins.
This small, tropical subfamily is best represented in the Old World, especially the Australasian region. A few species are found in northern Mexico and southwestern USA. They nest in the soil and are primarily subterranean in habit so they are rarely encountered. These ants exhibits a blending of army ant and ponerine traits both morphologically and biologically. Little is known concerning the behavior of the New World forms, but they are predaceous and carnivorous and the colonies are small. Wilson (1958) studied the behavior of several species from Melanesia and Australia and found them all to be myrmecophagous, feeding on the broods and sometimes adults of other species of ants. He suggested that these ants carry on an alternating, group foraging and raiding behavior pattern by which the colony efficiently exploits the surrounding territory.
Recognition. Antenna 11 or 12-segmented. Antennal sockets located very close to the anterior margin of the head; the clypeus is reduced to a very narrow band in front of them. Frontal carinae not expanded laterally so that the antennal sockets are completely visible in full face view. Eye very small to absent. Mesosoma attached to the gaster by a single segment, the petiole. Gaster with pronounced constriction between the first and second segments. Pygidium (upper surface of last visible gastral segment) with a row of denticles or peg-like teeth on each side.
Similar Subfamilies. The reduced clypeus, small eye, and exposed antennal sockets are similar to the army ants, subfamily Ecitoninae. However, the teeth on the pygidium clearly separate this subfamily from all others. However, these teeth may be short and hidden by hairs so the pygidium must be carefully examined.
Species in this genus are mass foraging predators of termites. Some species have a dichthadiiform queen (similar to army ant queens) (Brown, W.L. 1975: 41). Two species are found in the Nearctic region, but they are rarely collected since they are primarily subterranean.
Recognition: Small to moderate size. Often polymorphic. Body elongate and cylindrical. Almost always reddish-brown to dark brown. Body smooth, shining, and glossy (except for dorsum of petiole and sides of mesosoma and petiole). Mandible usually without teeth except for apical angle or tooth. Clypeus with broadly concave medial anterior border; often with lateral teeth. Frontal carinae usually not covering antennal insertions. Antennal insertions nearly touching. Antenna 12 segmented; scape short. Eye usually very small (large in A. texanus). Pygidium (terminal segment of gaster) with two rows of large, upwardly directed teeth that converge posteriorly.
This is a pantropical genus with about 8 New World species, two of which are found in southwestern United States.
Recognition: Length 2.5-3.5 mm. Body elongate and cylindrical. Mandible subtriangular, with an indistinctly crenated masticatory border. Frontal carinae close together; not concealing the antennal insertions. Antennal insertions nearly touching. Each gena marginated ventrally by a carina or ridge that runs forward from posteroventral corner of head for a distance one-quarter to one-half the head length in side view; antennal sockets bordered laterally by a second carina or ridge that extends to lateral lobe of clypeus or projects past anterior clypeal border as a blunt tooth. Antenna 11-segmented; scape short, curved, greatly enlarged apically; not extending much beyond middle of head. All funicular segments except the first and last are broader than long; last segment forming a club that is about as long as the combined length of the preceding 5 segments. Eyes apparently absent. Mesosoma subcylindrical; dorsal sutures absent (or very faint). First two gastral segments separated by a very distinct constriction. Second gastral segment occupying about half of the gaster. Pygidium (terminal segment of gaster) with two rows of small spines or teeth that converge posteriorly.
There are 31 species in 8 genera in the Nearctic region where they are found primarily in the southern portion of the United States. In the field, ants of this subfamily can usually be recognized by their small size, petiole a single segment, thin often translucent integument and their characteristic odor. Many members of this subfamily have a characteristic appearance in full face fiew, the "dolichoderine face." The eyes are large and are located at or in front of the midlength of the head and are located towards the centerline of the head so that the outer margin of the eye is well inside the lateral margin of the head.
Recognition. Some species with teeth or denticles on basal margin of mandible. Promesonotal suture usually present. Propodeal lobe absent. The mesosoma is attached to the gaster by a single segment, the petiole.The gaster does not have constrictions between between segments.The sting is absent and the opening at the tip of the gaster is slit-like. This slit-like opening is difficult to directly observe but is usually inferred by the absence of an acidopore (circular opening usually fringed by hairs). Integument thin often translucent.
Similar Subfamilies. Species of Dolichoderinae are often confused with species of subfamily Formicinae because both a have a single segmented petiole, lack a sting, and often are of similar body size and shape. Doichoderines always have a slit-like opening at the tip of the gaster whereas formicines have an acidopore (small circular opening that is often fringed by hairs). Most Nearctic dolichoderines have a very thin integument (Dolichoderus is the exception) while most formicines have a thicker integument (exceptions being Brachymyrmex and the uncommonly collected genus Plagiolepis). Members of subfamily Ponerinae are also small and have a single segmented petiole. Ponerines always have a well developed sting although it may be retracted into the gaster and impossible to see. Additionally, ponerines have a constriction between the first and second gastral segments (absent in the ponerine genera Odontomachus and Anochetus which are easily identified by their long, linear mandibles).
**************** Bracy mistaken for a Dolichoderinae ***************************8
The four species in this genus form colonies are small to moderately large, and nests are constructed in the soil, in curled leaves and hollow stems of plants, and in cartons attached to plants. Workers attend honeydew excreting insects and feed on small arthropods. Some forms emit a fluid which has a peculiar smoky or pungent odor (Smith, D.R. 1979: 1415).
Recognition: Integument thick, hard, and strongly sculptured. Underside of the head near the base of the mandible with a weak to well-developed flange that is sometimes tooth-like. Metanotal impression distinct. Propodeum with declivitous face distinctly concave.
Similar Genera: This genus is unlikely to be confused with any other Nearctic dolichoderines. It is clearly distinguished by the combination of thick, sculptured integument, distinct metanotal impression, and concave declivitous face of propodeum. However, with a single segment (the petiole) separating the mesosoma and the gaster plus the integument thick and sculptured, Dolichoderus can easily be mistaken for a member of subfamily Formicinae. The absence of an acidopore places Dolichoderus in subfamily Dolichoderinae. Also, no Nearctic member of subfamily Formicinae has a propodeum with a distinctly concave declivitous face.
These ants construct nests in the soil which are surmounted by irregular or crater like mounds of soil. They are usually found in open sunny areas in situations where other ant species find conditions intolerable (Smith, D.R. 1979: 1420). The workers are predaceous general foragers. They are active and aggressive and emit a fluid with a disagreeable odor. These ants are common and often abundant in the southern USA. There are 14 species.
Recognition: Maxillary palp with third segment elongate, about equal to or longer than combined lengths of segments 4-6. Psammophore usually present. Mandible with apical tooth enlarged, much larger than the preapical tooth. Anterior clypeal margin with numerous elongate, curved hairs that extend beyond (rarely just to) the apices of the closed mandibles. Propodeum with a prominent conical or pyramid-shaped process at juncture of dorsal and declivitous faces.
Similar Genera: The cone-shaped structure on the propodeum clearly separates Dorymmyrex from all other Nearctic dolichoderines. The shape of the propodeum could lead to confusion with the formicine genus Lasius. In Lasius, the propodeum forms a broad, elevated ridge rather than a cone-shaped process. Lasius also has an acidopore at the tip of its gaster, psammophore absent, and maxillary palps with third segment not elongate.
The three species in this genus are inhabitants of xeric habitats and are seldom found in forested or moist sites. Nests are in the ground under rocks or with small craters. Workers forage for honeydew and arthropods on the ground or in the trees. They are usually active during the warmer parts of the day, and they forage singly or in conspicuous columns (Shattuck, 1992c: 92, 94).
Recognition: Psammophore absent. Mandible with 5 teeth and 0 to 2 denticles. In profile, clypeus with 2 or more long, straight hairs projecting forward and/or upward; 2 or more hairs (usually longer than the straight hairs) originating at or near the anterior margin that curve downward over anterior surface of closed mandibles. Pronotum with 2 long hairs (at least 1/3 longer than others on pronotum) and 1 to about 14 short hairs. Metanotal impression slight to moderate; in profile, mesonotum and propodeum not forming a continuous, smooth curve. Petiolar scale present though sometimes small. First gastral tergite projecting anteriorly and, in dorsal view, concealing the petiole.
Similar Genera: Member of genus Forelius are easily confused with other Nearctic dolichoderines. Tapinoma is distinguished by the absence of a petiolar scale although some Forelius specimens will have a small petiolar scale overhung by the gaster. Liometopum species are moderately polymorphic with mesosoma in profile evenly convex and lacking the metanotal impression of Forelius. Linepithema is most similar to Forelius.
| Forelius | Linepithema | |
| Hairs on anterior margin of clypeus | Long and ventrally curved | Absent or shorter and straight |
| Basal margin of mandible | Without denticles | With denticles |
| Metanotal impression | Moderate | Distinct |
| First gastral tergite | Overhanging petiole | Not overhanging petiole |
The members of this genus are adventive worldwide in warm or temperate areas. They are generalized foragers (Brown, 2000: 56). North America has two introduced species. One, L. humile (= Iridomyrmex humilis), is called the Argentine ant and is a pest species.
Recognition: Mandible usually with 5 teeth and 5 to 13 denticles; the apical and subapical teeth prominent and notably larger than the preceding teeth; third, fourth, and basal teeth separated by numerous denticles. Anterior margin of clypeus with a broad, shallow concavity. In profile, clypeus with 2 (occasionally more) long, straight hairs projecting forward and/or upward; long, downward curving hairs originating at the anterior margin commonly absent, but if present, shorter than straight hairs. In profile, propodeum forms a prominent, rounded convexity that is relatively distinct from the profile of the remainder of the mesosoma. Metanotal impression distinct. Propodeum with dorsal face as long as or longer than declivitous face; in lateral view, the juncture of the two faces usually evenly convex (rarely weakly angulate). Erect hairs on body few.
Similar Genera: Forelius is most similar to Linepithema. See the table under Forelius.
These ants nest in the soil beneath cover or under bark or in crevices in trees, and the nest chambers are usually subdivided by a network of paper like material. Colonies are often populous. Workers forage in files sometimes several hundred feet long and commonly attend coccids and aphids. They are pugnacious and eject a repellent secretion with a strong and disagreeable odor (Smith, D.R. 1797: 1417). They are generalized foragers (Brown, W.L. 2000: 56). There are three species.
Recognition: Moderately polymorphic. Psammophore absent. Mandible with about 7 to 9 teeth on the masticatory margin; an indistinct basal angle; 3 to 5 denticles on the basal margin. Head with posterior margin concave. Head broadening posteriorly and narrowed anteriorly. Mesonotum and propodeum forming a smooth, continuous profile that may be either flat or convex; metanotum without dorsal impression (reduced to a suture across the dorsum that does not clearly interrupt the profile of the mesonotum).
Similar Genera: This genus is easily separated from all other Nearctic dolichoderines by its head shape, profile of mesosoma continuous, and its polymorphism. It is, however, easily confused with the formicine genus Camponotus. Both genera are polymorphic and have a continuous profile of the mesosoma. Camponotus differs by having an acidopore at the tip of the gaster, mandibles with 7 or fewer teeth, head with posterior margin rarely concave. Also, Camponotus lack dentition on the basal margin of the mandible.
This genus has 4 species that are found in the Oriental and Australian regions. Its members are epigaeic generalized foragers. One species is adventive in North America (Brown, W.L. 2000: 59).
Recognition: Clypeus with a broad, shallow concavity on medial anterior margin. Metanotal impression forming a narrow, distinct notch in the relatively flat dorsal surface of the mesosoma. Propodeum with declivitous face concave; in lateral view, sharply angulate at the juncture of the dorsal and declivitous faces. Petiolar scale vertical, not inclined anteriorly, and reaching upwards almost to the level of the propodeum.
At least one of the three North American species is introduced. Nests are found in a variety of situations and workers commonly attend honeydew excreting insects. All of the species emit a substance with an odor similar to that of butyric acid (Smith, D.R. 1979: 1421). On species, T. sessile, is quite common and widespread and has the common name the odorous house ant.
**** common - see Smith, 1965
Recognition: Mandible with 12 to 14 teeth decreasing in size from apex to base; basal angle absent. Anterior border of clypeus with a weak to distinct emargination. Pronotum without erect hairs. Petiolar scale absent (rarely present but minute). In dorsal view, 4 gastral tergites visible; the fifth (terminal) tergite is reflexed forward ventrally so the anus is not located at the terminus of the gaster when viewed laterally (note that this character works well with fresh and alcohol material, but if the specimen is shriveled, it may be impossible to accurately judge).
Similar Genera: This genus is most similar to Technomyrmex which differs by having 5 gastral tergites visible in dorsal view and erect hairs on pronotum.
This genus has 60 species that are found in the Old World tropics. The one species found in the United States has spread worldwide as a tramp species
Recognition: Mandible with 12 to 14 teeth decreasing in size from apex to base; basal angle absent. Pronotum with erect hairs on dorsal surface. Petiolar scale absent (rarely present but minute). In dorsal view, 5 gastral tergites visible. The terminal tergite is not reflexed ventrally and thus the anus is located at the terminus of the gaster in lateral view.
Similar Genera: This genus is most similar to Tapinoma which differs by having 4 gastral tergites visible in dorsal view and is without erect hairs on pronotum.
Members of this subfamily are known as army ants and are sometimes referred to as legionary ants. The Nearctic region is home to 27 species in three genera with the vast majority of species in genus Neivamyrmex. They can be found throughout northern Mexico and southern USA with a northward extension in the Mississippi River valley. Army ants are predaceous and are known for their foraging expeditions. Army ants exhibit a number of morphological and biological peculiarities not common to most ants such as wasp like males, wingless termite like females, blind workers, and their raiding and emigrating behavior. Rettenmeyer (1963) outlined the following traits in which they differ from other ants: (1) They feed almost exclusively on animal prey which is collected by large groups of raiding workers; (2) their raiding columns usually connect to the nest by at least one continuous column; (3) the entire colony periodically and frequently emigrates to new nest sites; (4) emigrations are largely dependent on the size, caste, age, and range of ages of the brood (or broods); and (5) the colonies are founded by division of an entire colony into two (or possibly several) daughter colonies. Other ants may possess some of these traits, but not all of them (Smith, D.R. 1979: 1326). Group raiding allows army ants to exploit food sources unavailable to other ants: large arthropods and the brood of other social insects. These prey are not normally accessible to ants foraging individually or in small groups, but they can be overcome when swarmed by large numbers of attackers.
Recognition. Antenna 12–segmented. Antennal sockets located close to each other and very close to the anterior margin of the head; the clypeus is reduced to a very narrow band in front of them. Frontal carinae not expanded laterally into frontal lobes so that the antennal sockets are completely visible in full face view. Eye with either a single facet or absent. Propodeum without spines or angles. Mesosoma attached to gaster by two segments, the petiole and postpetiole. Pygidium without teeth.
*** Propodeal lobe absent???????????????????????????????????
Similar Subfamilies. The reduced clypeus, small eye, and exposed antennal sockets are similar to subfamily Cerapachyinae. The teeth on the pygidium clearly distinguish Cerapachyinae. However, in California, Cerapachyinae workers (genus Cerapachys) have been taken as they were walking with a column of army ants (Neivamyrmex sp.) so collections of army ants should be carefully examined for the rare Cerapachys (Snelling, Cover & Fisher). Two other subfamilies, Pseudomyrmecinae and Myrmicinae have the mesosoma attached to the gaster by two segments, but in both of these subfamilies the eyes are much larger than in Ecitoninae.
This Neotropical genus has one species that reaches the United States.
Recognition: Scape width near apex less than one-third its entire length; flagellum slender. Propodeum without teeth or spines. Tarsal claw with median tooth.
Most species are found in the southwestern states with a few ranging east to the Atlantic coast and as far north as Virginia, Ohio, Illinois, and Iowa. The species are hypogaeic and are found in the soil under objects, though some have been reported from rotten logs and stumps. Some may carry on their foraging and emigrating activities during daylight, but most are apparently nocturnal in their activities. Most colonies have one functional queen, and new colonies are produced by fission. The cyclic pattern of nomadic and statary phases is similar to the tropical species, but in most Nearctic species the activity stops in the autumn and resumes again in the spring. There are 24 species.
Recognition: Clypeus reduced. Frontal carinae close together and almost vertical; not covering antennal insertions in full face view. Eye absent or reduced to a single facet. Scape short and robust, usually not extending much beyond posterior border of eye; segments of funniculus often enlarged. Propodeum without teeth or spines. Petiole longer than postpetiole and usually with a dorsal spine or tubercle. Tarsal claw simple; without a median tooth. This is by far and away the most common genus of army ant in North America.
These ants are subterranean but carry out terrestrial raids. Raiding is in columns of several ants wide and a few meters long and is sometimes done during the daylight hours (Smith, D.R. 1979: 1329). The single species is found in southern Texas.
Recognition: Width of scape near its apex more than one-third its entire length. Tarsal claw with median tooth.
intro
Recognition:
The one species in this genus was introduced into southern Texas for biological control purposes, but the attempt failed. They are predators, visit extrafloral nectaries, and some rob the broods of other ants (Brown, W.L. 2000: 52).
Recognition: Frontal carinae well separated and subparallel posteriorly; anterior sections of the frontal lobes and the antennal insertions are widely separated by the broadly rounded or triangular posterior extension of the clypeus. Mesonotum forming a prominent convexity surrounded by deeply impressed sutures. Mesonotum and propodeum forming distinct, separate convexities in front of and behind the metanotal groove. Mid and hind tibia with 1 spur. Coxa of hind leg without a dorsal tooth or spine. Tarsal claws on front legs (and often the mid and hind legs as well) with a subapical tooth.
Similar Genera: Ectatomma is most similar to genus Gnamptogenys sharing a similar overall habitus, configuration of the frontal carinae, tibial spurs, and tarsal claws. In Gnamptogenys, the mesonotum and propodeum form one nearly continuous profile and the mesonotum is not unusually prominent. The hind coxae are usually armed with a dorsal tooth or spine (when present, this is the simplest way to separate these genera).
These ants form small colonies of less than 100 individuals that nest in rotten logs or in the ground and are generalized predators and scavengers on arthropods. Two species are found in the United States.
Recognition: Frontal carinae well separated and subparallel posteriorly; anterior sections of the frontal lobes and the antennal insertions are widely separated by the broadly rounded or triangular posterior extension of the clypeus. Viewed in profile, mesonotum not unusually prominent. Mesonotum and propodeum form one nearly continuous profile (interrupted at most by a suture-like groove at their juncture). Coxa of hind leg usually armed with a dorsal tooth or spine. Tarsal claws on front legs (and often the mid and hind legs as well) with a subapical tooth.
Similar Genera: Ectatomma is most similar to genus Gnamptogenys
sharing a similar overall habitus, configuration of the frontal carinae, tibial
spurs and tarsal claws. In Ectatomma, the mesonotum forms a prominent
convexity surrounded by deeply impressed sutures, the mesonotum and propodeum
form distinct, separate convexities in front of and behind the metanotal groove,
and the coxa of hind leg never have a dorsal tooth or spine.
This subfamily is the predominant group of ants in North America. They are most common in the north and in the mountains with their numbers decreasing rapidly toward the southern part of the United States (Smith, D.R. 1979: 1422). The Nearctic region has 230 species and subspecies placed in 11 genera.
****************** Slave taking ********************
Recognition. Promesonotal suture usually present. Propodeal lobe absent. The mesosoma is attached to the gaster by a single segment, the petiole. The gaster does not have constrictions between between segments. The sting is absent, and the tip of the gaster has a small circular opening (the acidopore) that is usually surrounded by a ring of short hairs (see Bolton, 1994: fig. 160).
Similar Subfamilies. Species of Formicinae are most commonly confused with species of Dolichoderinae since both subfamilies have the mesosoma attached to the gaster by a single segment, lack a sting, and often are of similar overall size and shape. However, formicines can always be separated from dolichoderines by the tip of the gaster; in formicines there is a small circular opening (most easily seen by the ring of hairs surrounding it) while all dolichoderines have a slit-like opening. Species of Ponerinae also have the mesosoma attached to the gaster by a single segment, but they are less likely to be confused with formicines since ponerines are generally smaller than formicines. Ponerines can be separated from all formicines by the lack of an acidopore. Many ponerines have a well developed sting (absent in formicines) and most have a constriction between the first and second gastral segments.
Acanthomyops has 15 species found throughout the USA and is often common but little noticed. These exclusively subterranean ants are rarely found above ground except during the nuptial flight. In the field, a disturbed colony can often be identified by the strong lemon verbena or citronella odor that is emitted as a defensive chemical. Some species of Lasius have a similar odor, but it is much weaker.
Recognition: Acanthomyops can be distinguished from other Nearctic genera in subfamily Formicinae by the following combination of characteristics: Total length 2.5-5.5 mm. Body usually shining. Yellow, yellowish red, or orange subterranean ants. Palpal formula 3, 4. Maxillary palp short. Eye small; width usually half that of last antennal segment. Mesopropodeal spiracles often prominent and conspicuous. Propodeum with declivitous face usually only a little longer than the dorsal face. Dorsal face usually flat and evenly rounds into the declivitous face (i.e. there is no "Lasius peak").
Similar Genera: Acanthomyops is most similar to the species of Lasius in subgenera L. (Cautolasius) and L. (Chthonolasius). The ants in all three groups are subterranean and share common morphological adaptations to underground life: reduced eye size and pale red or yellow body color. Acanthomyops is distinguished by its maxillary palp being 3-segmented and short. Acanthomyops belongs to a group of genera all having similar size and general appearance. The following table is a quick guide to separating them, but the beginning student is cautioned to carefully key out all specimens and then compare them to reliably identified material.
| Acanthomyops | Maxillary palp short. Pale red subterranean ants. |
| Lasius | Propodeum with "Lasius peak." Mandibles with 7 or more teeth. |
| Myrmecocystus | Maxillary palp extremely long. Ants of the desert or arid areas. |
| Paratrechina | Dark, coarse, bristle-like hairs (absent in a few subterranean species). Scapes long. |
| Prenolepis | Mesosoma with distinct hourglass shape when viewed from above. Body smooth and very shiny. |
One species is known from southern Arizona.
Recognition: Small to minute yellowish ants. Mandibles slender with 3 to 4 teeth. Masticatory margin oblique, often not distinct from basal margin. Eye small to minute; located on sides of head anterior to midlength of head. Promesonotal and metanotal sutures present. Propodeum without distinct dorsal and declivitous faces.
These ants usually form small colonies in the soil under various objects and are easily transported by commerce in soil or plants. They are fond of honeydew and attend honeydew excreting insects (Smith, D.R. 1979: 1424). They are minute and have a very thin integument so that dried specimens often shrivel up. There are 3 described Nearctic species.
Recognition: This genus is common and widely distributed although its small size can make it easy to overlook. Brachymyrex is easily separated from other Nearctic genera in Formicinae by the following combination of characteristics: Total length 1.5-2 mm. Integument soft, flexible. Mandible triangular with a more or less distinct basal and masticatory margins. Eye well-developed; usually located near middle of side of head. Antenna 9-segmented. Metanotal impression distinct. Propodeum with dorsal face very short and a very long, sloping declivitous face. Hairs sparse, often absent on mesosoma.
Similar Genera: The thin integument and small size can lead to confusion with member of subfamily Dolichoderinae. The presence of an acidopore clearly places Brachymyrmex in subfamily Formicinae.
These are commonly referred to as carpenter ants, especially members of subgenus Camponotus, due to their habit of nesting in wood. However, some species in this diverse genus nest in soil or under stones. Worldwide, Camponotus is the largest genus of ants, and the 1500 species and subspecies represent almost 10 percent of all known ant species (Shattuck, 1999. Australian Ants: 93). They are found throughout the world with substantial numbers of species occurring in every biogeographical region (Bolton, 1995a). Along with Pheidole and Crematogaster it has been considered one of the most prevalent ant genera in the world based on species diversity, extent of geographic range, diversity of adaptations, and local abundance (Wilson, 1976). There are 51 species in North America.
******************* # of species here and for subgenera
Recognition: Total length 3-15 mm. Workers polymorphic (dimorphic in subgenus Colobopsis). Mandible with 4 to 6 stout teeth. Antennal insertion located well behind posterior margin of clypeus. Psammophore absent. In profile mesosoma continuously and evenly convex with the propodeum not depressed below the level of the promesonotum and the metanotum at most slightly impressed (usually not at all impressed). Mesosoma in dorsal view usually wedge shaped and tapering posteriorly. Metapleural gland orifice absent; the surface of the metapleuron uninterrupted by a gland orifice above the hind coxa and below the level of the propodeal spiracle; line or tuft of guard hairs absent.
Similar Genera: The Formicine genus Formica has similar size and habitus. It can be differentiated from Camponotus by: i) profile of thoracic dorsum clearly discontinuous, always interrupted by one or more distinct sutural impressions, never evenly convex ii) mesosoma, when viewed from above, not wedge shaped, usually constricted to some degree in middle and iii) lower rim of antennal insertion almost touching posterior margin of clypeus.
These are the true carpenter ants, and they nest in wood. These large ants live primarily in forested areas. They are most abundant in cool temperate or boreal forests where they can be a dominant component of the ant fauna. 10 species.
Recognition: Large ants. Total length of major 8–15 mm. Clypeus without a median carina (or feebly carinate). Antennal scape never flattened at base. Head of major at least a little wider than long. Clypeus with anterior margin irregular, not smooth and convex, no median emargination or notch; posterior and side margins meeting at a point (not connected by a smooth curve).
Similar Subgenera: Members of subgenus Tanaemyrmex can have similar general overall appearance but are distinguished by: clypeus with distinct median carina or antennal scape distinctly flattened at base (both conditions absent in subgenus Camponotus). Members of Tanaemyrmex also have head longer than wide. Note that minor workers of subgenus Camponotus may have head longer than wide and are easily confused with major workers of subgenus Tanaemyrmex. When identifying these ants it is important to have a nest series (and not just strays) so that the major workers can be identified. When elevation is taken into account, the ranges of subgenus Tanaemyrmex and subgenus Camponotus overlap significantly only in the southeast (Creighton, 1950a). In the Rockies and other western mountain areas, when both subgenera are found in the same general locality, subgenus Camponotus occupies the higher elevations and Tanaemyrmex the lower. Subgenus Myrmothrix is of similar size and habitus but is easily distinguished from subgenus Camponotus by: antennal scape flattened at base and legs with numerous long, erect hairs on all surfaces.
These ants are arboreal. The major workers have plug shaped heads that are used to block the entrances to the nests. They are most likely to be found in southeastern USA although they are not commonly collected. 8 species.
Recognition: Total length 3 - 6 mm. Dimorphic. Head of major worker distinctive: circular in cross section and abruptly truncate in front.
Only two species of this Neotropical subgenus reach the United States. They are not commonly collected.
Recognition: Total length 4-8 mm. Head longer than broad. Front of the head of the major obliquely truncate. Clypeus flat and scarcely higher than the adjacent portions of the cheeks.
These are arboreal ants that nest in dead branches, pine cones, and hollow plant stems. They are smaller, less common, and much less conspicuous than the true carpenter ants. 13 species.
Recognition: Total length 3.5-8 mm. Clypeus without a median carina or at most feebly carinate. Anterior margin of clypeus with a distinct semicircular median notch. Head of major worker approximately as wide as long.
This Neotropical subgenus extends into the extreme southern part of the United States. They usually nest under bark of trees, in branches of trees and shrubs, and in logs and stumps. These three species are uncommon.
Recognition: Small ants. Total length 3.5-7 mm. Posterior border of head straight or weakly emarginate. Mesosoma short; in the major, mesosoma no longer than length of head (excluding mandibles). Legs short. Mid and hind tibia without a row of graduated short bristles on the flexor surface. Head and mesosoma opaque or subopaque, densely punctate. Hairs on body (especially mesosoma and gaster) abundant, white, suberect to erect.
There are two species. One, C. floridanus, is a widespread pest ant in Florida and has the common name the Florida carpenter ant.
Recognition: Antennal scape flattened at base. Legs with numerous, long, erect hairs that are not restricted to the flexor surface and are not a row of bristles.
Most species of this subgenus nest in the soil under stones or other objects, and occasionally nests may be surmounted by a small crater. They are most common and diverse in the southwestern USA where it is usually found at low elevations and is replaced at higher elevations by subgenus Camponotus. 13 species.
Recognition: Clypeus distinctly carinate or if feebly carinate then scape flattened at base. Head longer than wide (often distinctly so).
Similar Subgenera: Members of subgenus Camponotus can have similar general overall appearance but are distinguished by: clypeus without distinct median carina and antennal scape never flattened at base. Major workers in subgenus Camponotus also have head wider than long. Note that minor workers of subgenus Camponotus may have head longer than wide and are easily confused with major workers of subgenus Tanaemyrmex. When identifying these ants it is important to have a nest series (and not just strays) so that the major workers can be identified. When elevation is taken into account, the ranges of subgenus Tanaemyrmex and subgenus Camponotus overlap significantly only in the southeast (Creighton, 1950a). In the Rockies and other western mountain areas, when both subgenera are found in the same general locality, subgenus Camponotus occupies the higher elevations and Tanaemyrmex the lower. Members of subgenus Myrmentoma are generally smaller in size and anterior margin of clypeus with median emargination or notch (absent in subgenus Tanaemyrmex).
This is the largest genus in North America. With 153 species it contains almost one-sixth of all North American species. Its members exhibit an impressive variety of habits including slave making, temporary social parasitism of various types, and various methods of nest founding and nest construction. Formicas are rarely found in habitats with less than 250 mm of rainfall per year, and most of the species are found in the temperate zones with deciduous or coniferous trees. Ants of genus Formica are more common, abundant, and diverse in the northern part of their range. In the far north it is not uncommon for them to be the dominant ants (Agosti, 1994b).
Recognition: Size medium to large (usually 4.5-9 mm; occasionally 2.5-4.5 mm). Mandibles with 7 or more teeth or denticles. Lower rim of antennal socket nearly touching posterior border of clypeus. Frontal carinae short but distinct with moderately to sharply angulate summit (this is best observed by looking perpendicularly down on summit of ridge). Ocelli well developed. Profile of mesosoma clearly discontinuous and not evenly convex, metanotal impression moderate to strong. Propodeum often distinctly depressed below level of promesonotum; dorsal face of propodeum longer than declivitous face. Mesosoma in dorsal view not wedge-shaped, usually constricted at least slightly at middle.
Similar Genera: Many members of the Formicine genus Camponotus have similar size and general appearance. They can be separated from genus Formica by:
Members of genus Polyergus take Formica workers as slaves and mixed colonies containing workers of both genera are not uncommon. Polyergus is easily distinguished from Formica by its falcate (sickle shaped) mandibles.
Workers of the genera Lasius, Paratrechina, and Prenolepis are usually much smaller than in Formica and are dark colored (never red or bicolored as some species of Formica). They are differentiated from Formica by:
Members of genus Acanthomyops are red, but they are also much smaller than Formica, and these subterranean ants are rarely seen above ground except during mating flights.
Ants of this genus nest in exposed soil, under objects or in rotting wood. Colonies are small to moderate in size. Workers attend and may foster honeydew-excreting insects. This genus includes some of our more common and widespread ants. There are 18 species.
Recognition: The genus Lasius is one of the most common and prominent in the Nearctic fauna. It occurs throughout North America. Its species occupy a wide variety of habitats, and they are among the most abundant of all ants. Lasius can be distinguished from other Nearctic genera in subfamily Formicinae by the following combination of characteristics: Total length 2-4 mm. Mandible with 7 or more teeth. Palpal formula 6, 4. Maxillary palp medium length to moderately long but not longer than head length (excluding mandibles). Antenna 12-segmented, and the scape surpasses the posterior border of the head by no more than 2-3 times the maximum diameter of the scape (usually less). Frontal carina indistinct or absent. Propodeum with declivitous face decidedly longer than dorsal face, both faces meeting at an angle so that the propodeum in profile resembles a distinct upward facing "peak" with a more or less rounded apex (this is characteristic of the genus and is sometimes referred to as the "Lasius peak").
Similar Genera: Lasius belongs to a group of genera all having similar
size and general appearance. See the table under Acanthomyops.
Queens form new nests independently and not as temporary social parasites. 3 speciess
Recognition: Maxillary palps medium length, 6-segmented, last 3 segments subequal in length. Eye very small; not more than 6 facets in greatest diameter and less than 35 facets total. Color light yellow to yellowish brown. Metapleural gland opening not reduced; greatest width of the gland opening measured perpendicular to its long axis is greater than the maximum width of the propodeal spiracle (including darkened rim).
Similar Subgenera: These ants are easily confused with subgenus Chthonolasius which have a slightly larger eye and a reduced metapleural gland opening. Genus Acanthomyops has 3-segmented maxillary palps. Subgenus Lasius can be separated from subgenus Cautolasius by the following characteristics: eye much larger and a longer terminal segment of the maxillary palps (Lasius (Lasius) sitiens is an exception to the maxillary palp criteria).
The 8 species of this subgenus are primarily subterranean and are infrequently seen above ground. Nest founding is by temporary social parasitism. The female enters a nest of the host species, eventually kills the rightful queen, and uses the host workers to tend her brood.
Recognition: Maxillary palps 6-segmented, short, last 3 segments subequal in length. Eye small; 10–12 facets in greatest diameter and more than 35 facets total. Color light yellow to yellowish brown. Reduced metapleural gland opening; greatest width of the gland opening measured perpendicular to its long axis is less than the maximum width of the propodeal spiracle (including darkened rim).
Similar Subgenera: This group is easily confused with subgenus Cautolasius which has a slightly smaller eye and a normally developed metapleural gland opening. Genus Acanthomyops has 3–segmented maxillary palps.
This is by far the most common and conspicuous subgenus. It has 7 species. Queens form new nests independently and not as temporary social parasites.
Recognition: Maxillary palps moderately long, last 3 segments subequal in length. Eye large; at least one-fifth of head width and usually more. Color usually light brown to blackish brown (light colored in L. sitiens). Metapleural gland opening not reduced; greatest width of the gland opening measured perpendicular to its long axis is greater than the maximum width of the propodeal spiracle (including darkened rim).
Similar Subgenera: Subgenus Cautolasius can be separated from subgenus Lasius by the following characteristics: eye much smaller and a shorter terminal segment of the maxillary palps (Lasius (Lasius) sitiens is an exception to the maxillary palp criteria).
This genus is typical of arid plains and deserts. The ants nest in soil, the nest being surmounted by a small crater, usually in medium-sized colonies of 1,000 to 3,000 workers. Some forms are apparently entirely predaceous or carnivorous while others live on honeydew and nectar obtained from plants or the secretion of galls. Repletes are known to occur in many species. Ants of this genus are commonly called "honey ants" because of the honeylike substance stored in the gasters of the repletes. There are 42 species.
Recognition: These ants are common in the deserts of southwestern USA, northern Mexico, and arid areas of the west. The species that forage during the day typically are dark brown to black whereas the nocturnal foragers have very large eyes and are usually pale yellow to reddish. They can be recognized by their extraordinarily long maxillary palps, a character state unique to this genus. Myrmecocystus can be distinguished from other Nearctic genera in subfamily Formicinae by the following characteristics. Total length 2.2-9 mm. Some species polymorphic. Maxillary palps longer than head length (excluding mandibles); the 3rd and 4th segments each as long or longer than the 2 terminal segments combined. Frontal carinae subparallel. Psammophore usually present (sometimes weakly developed). Ocelli sometimes present.
Similar Genera: Myrmecocystus most closely resembles the genus Lasius
and some Myrmecocystus species have a propodeum with a "Lasius
peak". However, Lasius is uncommon in deserts or arid areas,
and the two genera are easily separated by their maxillary palps. Myrmecocystus
belongs to a group of genera all having similar size and general appearance.
See the table under Acanthomyops.
This is a Neotropical genus represented in the USA by a single species. It is exclusively arboreal, and its natural history is poorly known.
Recognition: Antenna with 10 or 11-segments; with a very distinct club. Eye well developed, length much greater than the minimum width of the scape. In profile, propodeum sharply depressed below the level of the promesonotum. Color reddish brow to blackish.
************* intro - Trager
Recognition: Paratrechina can be distinguished from other Nearctic genera in subfamily Formicinae by the following combination of characteristics: Total length 1.5-3.5 mm. Mandible with 5 or 6 teeth. Antenna 12-segmented; scape frequently surpassing posterior border of head by 4 or 5 times the maximum diameter of the scape or more; funiculus without a club; funicular segments longer than broad; terminal segment at least twice as long as any other segment. Eye usually well-developed and about one-fifth or more as long as the head. With head in full face view the eyes are usually at or in front of the midlength of the sides. Dorsal surface of head and mesosoma usually with coarse, bristle-like hairs that are often dark brown or black and are arranged in pairs.
Similar Genera: Most species of Paratrechina can be recognized by the
long scape and the presence of dark colored, coarse, bristle-like hairs (absent
in some subterranean species). Paratrechina belongs to a group of genera
all having similar size and general appearance. See the table under Acanthomyops.
A single tramp species is established in California and is to be looked for in the Gulf States (Cover, in Hölldobler & Wilson, 1990: 68).
Recognition: Small, total length about 2 mm. Antenna 11-segmented; scape surpassing occipital border by less than one-quarter of its length. Eye large with more than 20 facets in greatest diameter. Propodeum rounded and without teeth or spines.
Similar Genera: Some species of Plagiolepis have a thin integument. This combined with their small size makes them easily confused with species of Tapinoma (subfamily Dolichoderinae). Members of Tapinoma have a slit shaped cloacal orifice at the tip of their gaster that is not fringed by hairs.
The three species in this genus are obligatory or true slave-making ants. In nest founding, the female enters a nest of the host species, eventually kills the rightful queen, and uses the host workers to tend her brood. A colony of Polyergus will conduct slave raids on nests of species of Formica, and workers of the host are taken and used by the Polyergus colony to feed and rear the brood and excavate the nest.
Recognition: Polyergus specimens are most commonly seen above ground when conducting slave raids. These large ants are distinctive looking and easily recognized. Total length 4-7 mm. Mandibles falcate (sickle shaped), with numerous denticles but no teeth. Lower rim of antennal socket nearly touching posterior border of clypeus (distance between them less than 1/4 the maximum diameter of the antennal socket). Antennae 12 segmented, filiform; scape slightly thickened apically. Eye well-developed; located more than its greatest diameter from the base of the mandible. Ocelli distinct. Head subrectangular. Metanotal impression strong with a pair of distinct proterburant spiracles. Propodeal spiracle oval to slit shaped. Metapleural gland opening indistinct. Petiole a thick, rounded node. Pilosity sparse especially on mesonotum. Body shining and yellowish to reddish. Highly variable morphology especially color and scape length. Single specimens (or a short series) difficult or impossible to determine the species.
Similar Genera: Polyergus is a close relative of genus Formica. The two are easily distinguished by their mandibles. All species of Formica have triangular mandibles with distinct masticatory and basal margins.
The one Nearctic species in this genus is one of the few ants that are specialized for cold temperature foraging. They often build their nests deep underground staying inactive during the summer months. Returning to activity when the weather cools, they can be found foraging even at freezing temperatures where they are often the only ants visibly active. Workers are exceedingly fond of honeydew but also feed on secretions of floral and extrafloral nectaries, exudates from galls, earthworms, arthropods, and ripened or decaying fruits. Repletes are common.
Recognition: Prenolepis is a common and widespread genus represented in the Nearctic region by a single species. It can be distinguished from other Nearctic genera in subfamily Formicinae by the following combination of characteristics: mandible triangular, with 5 or 6 teeth (rarely 7). In dorsal view mesonotum severely constricted giving the mesosoma a distinctive hourglass-like shape. Dorsal surface of mesosoma smooth and very shiny.
Similar Genera: Prenolepis is most often confused with Lasius
or Paratrechina. Viewing Prenolepis from above should immediately
reveal the distinctive and characteristic mesosoma. Although Paratrechina
also has a constriction in the mesosoma, it is not nearly as pronounced as in
Prenolepis and dark, coarse, bristle-like hairs are found only in Paratrechina.
In Lasius, the mesosoma is at most weakly constricted, and, its surface
is coarse and dull. If in doubt, a count of the number of teeth on the mandible
will separate the two. Prenolepis belongs to a group of genera all having
similar size and general appearance. See the table under Acanthomyops.
On a world wide basis, this is by far the largest subfamily of ants. As to be expected in such a large group, myrmicines display a wide variety of habits and natural histories. Many species are generalist predators and scavengers. Some specialize on hunting small, soft bodied springtails (Collembola) in the leaf litter and rotting logs. Others are seed harvesters with a significant impact on the seed dispersal of plants.
Recognition: Clypeus well developed; usually extending posteriorly between the frontal lobes. Frontal carinae expanded laterally into frontal lobes that at least partially cover the antennal sockets in full face view. Antennal sockets usually well-separated and set back from the anterior margin of the head. Eyes usually present, conspicuous, and with many facets. Promesonotal suture usually absent. Propodeal lobe often present. Mesosoma attached to gaster by two segments, the petiole and postpetiole.
Similar Subfamilies: Two other subfamilies, Pseudomyrmecinae and Ecitoninae, have the mesosoma attached to the gaster by two segments, and in both of these subfamilies the frontal carinae are short, close together and do not conceal the antennal sockets in full face view. In Pseudomyrmex the eyes are much larger than in Myrmicinae, and in Ecitoninae they are much smaller.
This is a Neotropical genus with one species found in southwestern United States. They are found primarily in grassland and semidesert areas. These fungus-growing ants usually collect grass as the substrate for growing fungus. They are comparable to Atta in biology and economic importance but colonies are apparently not so large and the leaf collecting habits not so extensive.
Recognition: Moderately polymorphic. Total length 2.3-6 mm. Antenna 11-segmented without a well defined club. Frontal carina with a lobe expanded laterally covering the antennal socket. With a carina near the inner border of the eye extending posteriorly. Posterior corners of head with several spines or tubercles, one of which is much larger than the others. Dorsum of mesosoma with at least 4 pairs of spines, teeth or large tubercles. Gaster tuberculate.
Similar Genera: Acromyrmex is most similar to genus Atta. The two genera can be readily separated by the following differences: 1) The workers of Acromyrmex are less strongly polymorphic than in Atta; the size ratio of largest to smallest workers is lower in Acromyrmex. 2) The dorsum of the mesosoma has 4 pairs of spines in Acromyrmex but only 3 in Atta. 3) The dorsum of the head and the tergum of the first gastral segment is roughened and tuberculate in Acromyrmex and smooth in Atta.
vs. Trachymyrmex
Brief explanation. No worker caste.
Most species of the 23 species in this genus nest in soil beneath a covering object but some may be in rotten logs or arboreally in dead branches. They are largely, if not entirely, carnivorous (Wheeler, G.C. & Wheeler, J. 1986g: 35).
Recognition: These ants have an elongate, slender habitus. Total length 3.25-12 mm. Monomorphic. Palpal formula 4, 3. Psammophore absent. Antenna 12-segmented; last 4 segments enlarged but not forming a distinct club. Eye large, convex, and located near midlength on side of head. Head longer than broad and often noticeably narrower behind the eyes than in front of them. In profile, propodeum substantially depressed below the level of the pronotum; mesonotum forms a more or less sloping surface between them. Propodeum usually with a pair of spines. Petiole with anterior peduncle. Two large (8-12 mm) species common in the deserts in southwestern USA and Mexico (A. albisetosa and A. cockerelli, both formerly in Novomessor) can be distinguished from other Aphaenogaster by a weak metanotal impression that does not interrupt the smooth, sinuous profile of the mesosoma. In all other Nearctic Aphaenogaster, the metanotal impression is distinct and the profile of the mesosoma is not smooth and sinuous (Cover, in Hölldobler & Wilson, 1990: 67).
Similar Genera: The genera Aphaenogaster, Messor, and Pheidole all have a similar and distinctive shape to their mesosoma with a sloping mesonotum connecting the higher pronotum to the lower propodeum. Pheidole is easily distinguished from the other genera by: dimorphic, palpal formula of 2, 2 (or 3, 2), and having a strongly defined 3-segmented apical club on the antennae. Usually, Pheidoles are much smaller in size. Messor can be much more difficult to separate from Aphaenogaster. Messor is found only in the western portion of the Nearctic region and can be differentiated by: psammophore usually present; head quadrate and not narrower behind the eyes than below them; mandibles short and powerful, their outer margins strongly curved towards midline; and postpetiole only slightly constricted posteriorly.
These leaf cutter ants are a Neotropical genus with two species found in southern United States. The nests, which are deep in the soil and usually have many lateral and vertical entrances, are often extremely large and contain numerous individuals. Workers defoliate both wild and domesticated plants, including trees, and they feed on a fungus grown from a substratum composed of macerated leaves and other vegetable matter (Smith, D.R. 1979: 1413).
Recognition: Strongly polymorphic. Total length 1.5-12 mm. Clypeus with median emargination flanked by a pair of teeth. Antenna 11-segmented without a well defined club. Frontal carina expanded laterally into a lobe covering the antennal socket and a spine posterior to the lobe. A longitudinal carina median to the eye ending anteriorly in a small spine or tubercle. Posterior corner of head with a spine. Posterior portion of head and first gastric tergite smooth, not tuberculate. Dorsum of mesosoma with 3 pairs of spines or teeth. Legs long.
The colonies are small and nests are constructed in soil and in plant cavities. They are easily transported by commerce and all our five species may have been introduced (Smith, D.R. 1979: 1375).
Recognition: Small; total length 1.6–2.5 mm. Integument very finely sculptured, but without conspicuous punctures or rugae. Dorsal surfaces of body usually without erect hairs (except mandibles, clypeus, and apex of gaster). Clypeus with a projecting median portion that forms a shelf projecting forward over mandibles. Eye present, usually large and conspicuous, located on anterior half of the head. Antenna 12-segmented; usually with a distinct 3-segment club but the first club segment may be relatively small. Dorsum of mesosoma without sutures but the metanotal impression commonly (but not always) present. Propodeum armed with spines. Petiole with anterior peduncle. Postpetiole in dorsal view very broad, much broader than the petiolar node.
Similar Genera: Solenopsis globularia littoralis has a similar postpetiole but is easily distinguished by the distinct 2-segemented antennal club and propodeum unarmed.
This genus is mainly Neotropical with slight extensions into the United States. They are arboreal and form small colonies in cavities of plants, especially twigs. Food consists largely of honeydew and small arthropods. The soldier is believed to keep intruders from the nest by blocking the entrance hole with its head. The three North American species were formerly placed in genus Zacryptocerus (now a junior synonym of Cephalotes).
Recognition: Total length 3-6 mm. Polymorphic. Frontal carina greatly expanded laterally to cover sides of head. Antenna 11-segmented, enlarged apically but without a well defined club. Antennal scrobes long and deep, receiving the entire scape. Well developed, convex eye located close to posterior corner of head and at apex of antennal scrobe. Mesosoma dorsally flattened. Promesonotum sharply marginate at sides, often with irregular spines or tubercles. Petiole and postpetiole with prominent spines on sides. Legs short, femora enlarged. Body with short, appressed, silvery or grayish hairs.
These ants nest in moderately large colonies under objects in the soil, in wood, in cavities of plants, in insect galls, in carton nests of their own making, or even in the woodwork of buildings. Most are omnivorous but show a preference for sweets and tending honeydew excreting insects. Along with Pheidole and Camponotus it has been considered one of the most prevelant ant genera in the world based on species diversity, extent of geographic range, diversity of adaptations, and local abundance (Wilson, 1976). There are 30 North American species.
Recognition: This is a distinctive and easily recognized genus. Antenna 11-segmented; with a club of 3 (rarely 2) segements. Propodeum armed with spines. Petiole lacking a node on its upper surface. Postpetiole attached to the anterior dorsal surface of the first gastral segment. In profile, dorsum of gaster flat, feebly convex, or concave. This contrasts to the strongly convex ventral surface. In dorsal view, the gaster is heart-shaped and terminates in an acute point.
Similar Genera: The attachment of the postpetiole to the gaster is distinctive and separates these ants from all others. In the field, they can often be seen with their gaster elevated over their mesosoma and pointing forward. This facilitates the spraying of defensive chemicals.
There are 26 North American species.
Recognition: Antenna with a 3-segmented club. Petiole trapezoidal, broader anteriorly. Postpetiole viewed from above with two lateral lobes, one on each side of the midline of the body.
There are 4 North American species.
Recognition: Similar to Crematogaster (Crematogaster) but antenna with a 2-segmented club, dorsal surface of propodeum vestigial or lacking??????????, propodeal spines much shorter than the distance between their bases, petiolar node as long as broad or or longer than broad and subrectangular to subelliptical, color usually yellowish (darker in arizonensis). Postpetiole viewed from above not divided into two lateral lobes.
This is a rather large Neotropical genus with three species found in the southern United States. These ants form small colonies, usually in the soil, and live on fungi which they cultivate from a substratum of insect feces (Smith, D.R. 1979: 1410).
Recognition: Monomorphic. Total length 1.8-2.5 mm. Frontal carina moderately to strongly expanded laterally (and often forward) forming distinct lobes that, in some cases, cover most or all of the cheeks in full face view. Antenna 11-segmented without a well defined club. Antennal scrobe strongly developed and extending to the posterior border of the head. With a carina near the inner border of the eye extending posteriorly. Mesosoma short, stout, with a number of tubercles or longitudinal carinae. Gaster never tuberculate. Pilosity on dorsal surface absent or short and strongly appressed; hairs flattened, scale-like or strap-like; simple, erect or recurved hairs extremely scarce (usually absent) on dorsum of head and mesosoma.
The single species in this genus is a cryptic predator in the leaf litter.
Recognition: Mandible triangular, serially dentate. Mandibles close tightly against clypeal margin and each other. Antenna 7-segmented. Antennal scrobe present. Petiole and postpetiole without spongiform tissue. Tibia usually with one or more thick clavate or spatulate hairs at apex.
intro ********************************************************
Looks just like a Lepto. muscorum
Collection tech
5 species.
Recognition: Small, shining, narrow bodied ants. Palpal formula 5, 3 or 4, 3. Mandible usually with 6 teeth (sometimes 5); apical 2 teeth enlarged. Clypeus with anterior margin convex. Antenna 11-segmented with 3-segmented club. Eyes with short erect hairs. Head longer than broad; sides subparallel. Mesonotum in profile flat or slightly convex. Propodeal spines short or dentiform. Petiole without an anterior peduncle.
Similar Genera: These ants look much like Leptothorax muscorum but are distinguished by erect hairs on the eyes.
The single species in this genus is dulotic, enslaving and conducting raids on colonies of certain species of Temnothorax (= Leptothorax).
Recognition: Mandibles broad and edentate. Palpal formula 5, 3. Anterior margin of clypeus with prominent median notch or deep concavity. Frontal carina extending to about the apex of the scape; forming a small scrobe for the reception of the scape. Antenna 11-segmented; scape flattened at base. Head large and subrectangular. Propodeum armed.
Recognition: Small ants; total length 1.5-3.3 mm. Mandibles usually with 5 teeth (rarely 4 or 6 teeth) that decrease in size from apex to base. Antenna 11 or 12-segmented, with a 3-segmented apical club. In most species, profile of mesosoma flat, metanotal impression absent or faint (L. pergandei is an exception; in profile, promesonotum convex and metanotal impression distinct). Propodeum usually with teeth or spines (rarely unarmed). Petiole with or without an anterior peduncle. Pilosity usually short, stout, blunt hairs
Similar Genera: Similar in size and antennal structure to Cardiocondyla, but Cardiocondyla distinguished by: dorsal surfaces of body usually without erect hairs; petiole with anterior peduncle, and postpetiole in dorsal view much broader than long. Also similar in size and antennal structure to Tetramorium, but Tetramorium distinguished by: mandibles with 3 enlarged apical teeth followed by a row of 4 denticles, so that at least 6 (usually 7) teeth are present altogether (Leptothorax with 5 teeth decreasing in size from apex to base); maxillary palp 4-segmented (rarely 3) (5-segmented in Leptothorax); in many species of Tetramorium the frontal carinae are strongly developed and reaching almost to the posterior border of the head; anterolateral portions of clypeus raised into a ridge in front of antennal insertions; sting with an apicodorsal lamelliform appendage (sting simple in Leptothorax).
Recognition: Antenna 12-segmented. Dorsum of mesosoma not strongly arched. Metanotum deeply impressed. Petiole with an elongate anterior peduncle.
Recognition: Clypeus without median carina (but usually with carinae near the sides), usually with a median concavity that forms a longitudinal depression or trough. Antennal scapes often with erect or suberect hairs. Dorsum of mesosoma flat or feebly convex. Metanotum at most feebly impressed. Petiole without an elongate anterior peduncle.
Recognition: Dorsum of mesosoma strongly arched. Petiole with an elongate petiole.
Recognition: Clypeus with median, longitudinal carina (in addition to several lateral carniae). Scape usually without erect hairs. Dorsum of mesosoma flat or feebly convex. Metanotum not impressed; often no suture visible. Petiole without an elongate anterior peduncle.
Recognition: Petiole and postpetiole with spine-like protuberances.
Colonies are small and nests are usually found in openings in coniferous forests commonly under stones in creek or river bottoms. The ants of this genus are generally not aggressive, but they will sting when their nest is disturbed. Their sting can be very painful. The gait of the workers is characteristic: steady, deliberate, and unhurried but not sluggish. There are five North American species.
Recognition: Total length 3.5-8 mm. Monomorphic. Psammophore absent or weakly developed. Mandible with a long maticatory margin; 2 large apical teeth and 10 or more small teeth or denticles. Antenna 12-segmented with the terminal 5 segments enlarged but not forming a distinct club. Antennal scape bent at base. Promesonotal suture present but faint. Metanotal impression broad and deep. Propodeum without spines (blunt projections may be present). Petiole with small ventral tooth. Hind tibial spur finely pectinate. [Cuticle]
Similar Genera: Genus Manica is similar to Myrmica and has in the past been considered a subgenus of Myrmica. All species of Myrmica have propodeal spines and the metanotal impression is weak to distinct (broader and deeper in Manica). In the field, Manica is most likely to be confused with Pogonomyrmex. Species of Pogonomyrmex can be distinguished by: psammophore usually present, metanotal impression weak to absent, and propodeum often with spines. All species of Manica lack propodeal spines and have a deep metanotal impression.
These are harvester ants, most common in the arid Southwest. They feed on seeds and other Arthropods and usually nest in exposed soil where the nests may or may not be marked with a small crater or piles of chaff from seeds stored in the nest. They are docile ants which seldom sting. There are nine North American species.
Recognition: Most species strongly polymorphic but a few species monomorphic or weakly polymorphic. Mandibles short and stout, their outer margins strongly curved towards midline. Median portion of clypeus broad and shield-like, broadly inserted between widely separated frontal lobes. Psammophore usually present. Antenna 12-segmented. In full face view, head broad and blocky with a square to rectangular shape. In profile, promesonotum convex and frequently dome-like and sloping down steeply to metanotal impression. Promesonotal suture distinct on dorsal surface. Mesonotum bounded by impressions on all sides (this may be lacking in the smallest workers). In profile, propodeum substantially depressed below the level of the pronotum; mesonotum forms a more or less sloping link between them. Petiole with long anterior peduncle; petiolar node in profile narrow and often bluntly triangular to conical in shape.
Similar Genera: The genera Aphaenogaster, Messor, and Pheidole all have a similar and distinctive shape to their mesosoma with a sloping mesonotum connecting the higher pronotum to the lower propodeum. Pheidole is easily distinguished from the other genera by having a palpal formula of 2, 2 (or 3, 2), dimorphic, and a strongly defined 3-segmented apical club on the antenna. Usually, they are much smaller in size. Aphaenogaster is less common in the arid areas preferred by Messor. They can be distinguished from Messor by: psammophore absent; mandibles more slender; and head longer than broad.
Members of this genus are small in size and are particularly adaptable with respect to nesting sites. They may nest in various preformed cavities or in soil. Most species are Old World, but because of their adaptability and size, they are especially susceptible to distribution by commerce. Three of the 16 North American species have been introduced and are common tramp species and house pests (Smith, D.R. 1979: 1381-1382). One species, M. minimum, is common and widespread.
Recognition: Very small; total length 1-2.5 mm. Body smooth and shining (except M. pharaonis). Mandible with 3 or 4 teeth. In full face view, the midpoint of the anterior clypeal margin with a long, unpaired median seta that projects forward over mandibles. Clypeus usually with a pair of longitudinal carinae that form a pair of teeth on the anterior border. Antenna 12-segmented, with a 3-segmented club. Propodeum never with distinct teeth, rarely angulate, usually rounded. Petiole with distinct anterior peduncle; usually with a small subpetiolar process.
Similar Genera: Solenopsis also has a clypeus with a pair of longitudinal carinae that form a pair of teeth on the anterior border and a median clypeal seta. The Nearctic species of Solenopsis can be differentiated from the Nearctic species of Monomorium by its antenna being 10-segmented with a 2-segment club.
This is a small genus of leaf cutter ants with one species in North America.
Recognition: Monomorphic. Total length 1.8-2 mm. Frontal carina projecting forward and laterally beyond antennal insertions, forming conspicuous lobes that overhang the sides of the clypeus. Antenna 11-segmented; scape robust, last funnicular segment as long or longer than the 4 preceding segments. With a carina near the inner border of the eye extending posteriorly. Pronotum with a pair of prominent humeral spines and a pair of small tubercles between them. Propodeum with a pair of short spines. Node of petiole with a pair of spines. Postpetiole much broader than long, the posterior border emarginate. Hairs short and recurved. One species, M. hartmanni, known from Texas and Louisiana.
The single species of this genus is common in moist woodlands. Nests are infrequently encountered, but they are often taken via litter extraction. The ants in this genus are predators on mites (Brown, W.L. 2000: 58).
Recognition: Small (total length 2-3 mm). Brownish to black with lighter appendages. Antenna 12-segmented; with a distinct 3-segmented club. Eye small, inconspicuous. Mesosoma short and stout; much broader anteriorly than posteriorly. Humeri of pronotum angulate. Propodeum with 2 pairs of spines. Petiole short and subcylindrical; without an erect scale; without an anterior peduncle.
Similar Genera: The two pairs of pronotal spines and the subcylindrical petiole make this genus easy to identify. Both Myrmica and Tetramorium have a similar general appearance but both genera have only one pair of propodeal spines and an upright petiolar scale.
Members of this genus are quite tolerant of cold conditions. They are found as far north as Labrador and Alaska and are restricted to higher elevations in the southern parts of their range. The majority of species are found in forests and mountain meadows where they can be quite abundant. In general, they are associated with humid habitats, and, although there are a few species found in open grasslands, there are no desert inhabiting species. The moderate sized colonies nest in soil, rotten wood, or under cover of various objects. Mature colonies usually contain from several hundred to several thousand workers and from one to ten or even hundreds of queens (Wardlow & Elmes, 1996). As far as is known, all species of Myrmica are generalist scavengers and predators. Workers also feed on honeydew of Homoptera and exudates of plants. 25 North American species.
Recognition: Total length 3-6.2 mm. Monomorphic. Body with cuticle thick and with an armoured appearance; usually the cuticle strongly sculptured. Psammophore absent. Mandible with 6-10 teeth or denticles. Clypeus with longitudinal rugulae interrupted by posterior border of clypeus and not continuous with rugulae of rest of head. Antenna 12-segmented; scape usually curved or bent at base; funniculus enlarged apically forming an indistinct 3 or 4-segment club. Promesonotal suture absent. Metapleural impression interrupting the dorsum of the mesosoma in lateral view.. Propodeum with spines. Petiole with a short anterior peduncle and an anteroventral tooth or process. Tibial spurs on mid and hind legs finely pectinate in Nearctic species.
Similar Genera: The common species Tetramorium caespitum (Linnaeus) is easily confused with some Myrmica species. It can be distinguished by: clypeus with longitudinal rugulae continuous with rugulae of rest of head, mid and hind tibial spurs not pectinate. Some species of Pogonomyrmex are similar but they differ in: psammophore usually present and well developed, shape of petiole distinctive: in lateral view, node of petiole with a short, steep anterior face, a longer gradually sloping posterior face, and reaching its highest point at or near its anterior surface. Myrmica is similar to Manica but all species of Manica lack propodeal spines and have a deep metanotal impression.
Minor workers are exceptionally small (less than 1mm in length). They nest in the soil where they commonly are adjacent to an ant or termite nest. They are thief ants that prey on the eggs and larvae of the host colony. Apparently because of their very small size, host workers tend to ignore them (Shattuck, 1999. Australian ants: 149). One species.
Recognition: Dimorphic although majors seldom collected. Anterior clypeal margin with a pair of hairs that straddle the midpoint of the margin. Frontal carina extending well past eye. Eye minute with 5 or fewer facets. Antenna 11-segmented with a 2 segment club. Propodeum armed with a pair of short teeth.
This is a large genus of harvesting ants, and the majority of species are found in the arid Southwest. Most species have a dimorphic worker caste with majors (or soldiers) and minors which are not connected by intermediate sizes. The soldier is characteristic in having an enormous head, way out of proportion to the rest of the body, and may function as a seed husker. Most species harvest seeds for food and chaff piles are sometimes found around the entrances to the nests. Nests may have craterlike excavations when in exposed soil, or nests may be under stones or other objects and sometimes in rotten wood. Though the main diet normally consists of seeds, most species also feed on other animal food. Most colonies are small with 300 or fewer individuals. Along with Camponotus and Crematogaster it has been considered one of the most prevalent ant genera in the world based on species diversity, extent of geographic range, diversity of adaptations, and local abundance (Wilson, 1976).
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Recognition: Dimorphic (a few species polymorphic or trimorphic); with large broad headed workers (majors) contrasting with much smaller workers (minors) with proportionately much narrower heads. Palpal formula 2, 2 or 3, 2. Psammophore usually absent. Mandibles usually with 2 large apical teeth; with 6 or more teeth or denticles in minors; dentition reduced in majors. Antenna 12-segmented; with a well defined 3-segmented apical club that is as long as or longer than the remainder of the funniculus (rarely 4-segmented). Majors with hypostomal teeth. Minors with propodeum usually distinctly lower in elevation than pronotum; mesonotum sloping gradually (interrupted by a notch or depression at metanotal region) to the level of the propodeum or the mesonotum often as high as pronotum and separated from propodeum by a distinct step at metanotal impression. Metanotal impression distinct. Dorsal face of propodeum in profile flat or weakly concave (rarely convex). Propodeum armed with spines (rarely vestigial).
Similar Genera: The genera Aphaenogaster, Messor, and Pheidole all have a similar and distinctive shape to their mesosoma with a sloping mesonotum connecting the higher pronotum to the lower propodeum. Aphaenogaster can be distinguished by: monomorphic; mandible without the apical 2 teeth enlarged; antennal club indistinct and 4-segmented; and usually has a larger body size. Messor can be distinguished by: often polymorphic; psammophore present; mandibles broad; and a broad, square head. Species of Leptothorax are of similar size to minor workers of Pheidole but in profile their mesosoma is usually flat (sloping mesonotum in Pheidole). Leptothorax (Dichothorax) pergandei can easily be mistaken for a minor worker of Pheidole. The two are separated by the dentition on their mandibles. Pheidole has 6 or more teeth or denticles; apical 2 teeth much larger than the others and both located close to the apex. Leptothorax (Dichothorax) pergandei has 4 teeth decreasing in size from apex to base.
Leptothorax (Dich) pergandei can easily be mistaken for a minor worker of Pheidole. The two are separated by the dentition of the mandibles: L.(D.) pergandei has 4 teeth with the apical 2 being the largest 2) Pheidole has 6 or more teeth or denticles with apical 2 enlarged. 3) In L. (D.) pergandei the preapical tooth is located about 1/3 the distance along the mandible whereas in Pheidole both the apical and preapical teeth are located close to the end of the mandible
Members of this genus are collectively known as harvester ants and, because of their mound building habits, some species are among the most conspicuous ants in the arid regions of the western United States. The workers collect seeds for food, harvesting plants in their nesting areas by snipping off seeds with their mandibles. The seeds are stored and are the main food source though the ants are also scavengers of dead arthropods. Nests are in the soil in areas fully exposed to the sun; some are under stones and others are surmounted by soil craters or by small to huge mounds with or without coverings of gravel. Some species have a painful sting, procure seeds from cultivated crops and damage rangelands (Smith, D.R. 1979: 1353). 28 species.
Recognition: Total length 3.5-10 mm. Antenna 12-segmented, last 4 segments enlarged but not forming a distinct club. Psammophore usuall strongly developed (weakly developed or absent only in small species). Head subrectangular or subquadrate, broad in proportion to its length. Mesosoma with dorsal sutures absent or weakly developed. Metanotal impression slight or absent, not breaking the dorsal profile of the mesosome in lateral view. Propodeum usually armed with spines. Petiole with a long, anterior peduncle. In lateral view, node of petiole: with a short, steep anterior face, a longer gradually sloping posterior face, and reaching its highest point at or near its anterior surface. Mid and hind legs with finely pectinate tibial spurs. [ mono / poly ]
Similar Genera: Pogonomyrmex is questionably distinct from Ephebomyrmex. The Nearctic species of Ephebomyrmex can be differentiated by the following characteristics: psammophore feebly developed, head and mesosoma extensively and coarsely sculptured, femora strongly swollen, base of propodeal spines connected by a transverse keel, postpetiole in profile massive with a large bulbous ventral projection that is much deeper than long. Myrmica differs from Pogonomyrmex by lack of a psammophore and lack of the characteristic petiole of Pogonomyrmex. In the field, Pogonomyrmex is most likely to be confused with Manica. Species of Manica can be distinguished by: psammophore absent (or weakly developed), metanotal impression broad and deep, and propodeum never with spines.
The single species in this genus is dulotic enslaving colonies of certain species of Temnothorax (= Leptothorax).
Recognition: Mandible with 4 teeth. Anterior margin of clypeus broadly concave. Frontal carina extending well past the eye. Antenna 11-segmented, last 4 segments enlarged and forming an indistinct club; scape flattened at base. Propodeum armed.
Ants of this genus are widespread and sometimes common, but they are infrequently collected. They form small nests in the soil, litter cover, and logs. Since the workers are small, drab colored, and move very slowly, nests are rarely encountered. However, individuals are commonly found by litter extraction. They are specialized hunters on collembola (springtails) which are abundant in leaf litter and rotten logs. The workers of some species (Masuko, 1984) smear soil and detritus on themselves. This may camouflage the odor of the hunter and allow them to close on prey more efficiently. They are often found in or near the nests of other ants (Wesson & Wesson, 1939) apparently hunting the collembola that are found there. 38 species.
Recognition: Small; total length 1.3-2.5 mm. Mandibles subtriangular (rarely linear but never with a well developed apical fork of teeth). Buccal cavity (= mouth cavity; visible in ventral view of head) relatively short and wide; lateral margins not converging anteriorly. In ventral view, mandibles not arising from apex of labro-maxillary complex (often arising from sides of buccal cavity). Antenna with 4 to 6 segments; the apical 2 segments forming a distinct club; apical segment often longer than the combined length of the other segments of the funniculus. Antennal scrobe present, distinct, and extending above the eye. Head subcordate with posterior border strongly emarginate and posterior corners prominent and rounded. Petiole and postpetiole usually with spongiform tissue. Base of first gastric segment usually with longitudinal striations. Bizarre pilosity usually present; often clavate or spatulate.
Similar Genera: This genus can be confused with Strumigenys which is of similar size, head shape, also has spongiform tissue on the petiole and postpetiole, and is often with bizarre pilosity. Strumigenys can be distinguished by its long, linear mandible (subtriangular in most Pyramica) with a well developed apical fork consisting of 2 or 3 spine-like teeth at the extreme tip.
This is a neotropical genus, and only two species reach the southwestern USA. They are rarely collected.
Recognition: Clypeus with a pair of longitudinal carinae that do not form teeth on the anterior margin. Antenna 12-segmented; scape not reaching posterior margin of head; funniculus with a distinct 3-segment club that is longer than the rest of the funniculus; apical segment longer than combined lengths of other 2 club segments. In profile, mesosoma distinctly convex. Petiole with anterior peduncle but without a plate-like anteroventral process.
The 24 species of Solenopsis include both the fire ants and the thief ants. Fire ant colonies are populous, nests are usually mounds in exposed situations, and workers are aggressive.The imported fire ant is the most economically important ant. In contrast, the thief ants are small and inconspicuous. It is thought that their small size enables them to steal food from the nests of other, larger ants.
Recognition: Total length 1-7.5 mm Polymorphic or monomorphic. Clypeus usually with a pair of longitudinal carinae that form a pair of teeth on anterior border, often flanked by a pair of lateral clypeal teeth. In full face view, the midpoint of the anterior clypeal margin with a long, unpaired median hair that projects forward over mandibles. Antenna 10-segmented, with a clearly defined 2-segmented club. Metanotal impression broad and deep. Propodeum in profile rounded; not armed. Petiole with distinct anterior peduncle. Most species pale yellow to reddish brown (a few species dark brown to black). Most species predominantly smooth and shining usually with sparse, long hairs.
This is a relatively small genus of primitive ants. They are most abundant in northern hardwood or boreal forests. They often live in cool, dark, and moist forests where few or no other ants are found. Foraging is often seasonal and restricted to cool times of the year. Colony size is small typically ranging from a few dozen to several hundred workers with a mean of about 55 (Talbot, 1976a). Nests are in soil underneath rocks, logs, moss, or humus. These nests are often small, cryptic, and hard to find. As a result, nests are not frequently collected. It is much more common to take isolated workers through litter extraction. Little is known of their natural history. They are generalized predators on collembola and various larvae and are not know to atten honeydew excreting insects. 17 species.
Recognition: Small (total length 2.2-4 mm). Body heavily rugulose; brown to black colored. Clypeus usually with two longitudinal carinae that do not form teeth on the anterior margin. Clypeus compressed (both front to back and side to side). Eye usually small. Antenna 12-segmented with an indistinct 3 to 4-segmented club; scape not surpassing occipital corner. Promesonotum prominent and strongly convex. Metanotal impression present. Propodeum lower than promesonotum; usually armed with small teeth (rarely sharply angulate).
Similar Genera: This genus can be confused with Leptothorax (Dichothorax) pergandei since both have a similar profile to the mesosoma, but L. pergandei lacks the longitudinal carinae on its clypeus. Stenamma is most similar to Rogeria which is rarely collected and found only in southern Texas and Arizona. Rogeria can be distinguished by the lack of sutures on the dorsum of the mesosoma and antenna with a distinct 3-segmented club that is longer than the rest of the funniculus. Genus Aphaenogaster is somewhat similar but larger, scape surpassing occipital border, and promesonotal suture distinct.
The four species of the United States are believed to have been introduced. Colonies are small and nests are usually found in leaf litter, plant cavities, rotting wood, or under objects (Smith, D.R. 1979: 1403). As in Pyramica, they are specialized hunters of collembola in the leaf litter and rotten logs.
Recognition: Small; total length 1.3-2.5 mm. Mandibles long, thin, and linear; with an apical fork of 2 or 3 spine-like teeth at the extreme tip. Buccal cavity (= mouth cavity; visible in ventral view of head) relatively long and narrow; lateral margins converging anteriorly. In ventral view, mandibles apparently arising from apex of labro-maxillary complex. Antenna with 4 to 6 segments; the apical 2 segments forming a distinct club; apical segment often longer than the combined length of the other segments of the funniculus. Antennal scrobe present, distinct, and extending above the eye. Head subcordate with posterior border strongly emarginate and posterior corners prominent and rounded. Petiole and postpetiole usually with spongiform tissue. Bizarre pilosity usually present; often clavate or spatulate.
Similar Genera: This genus can be confused with Pyramica which is of similar size, head shape, also has spongiform tissue on the petiole and postpetiole, and is often with bizarre pilosity. Pyramica can be distinguished by its mandibles usually subtriangular (if long and linear then never with a well developed apical fork consisting of 2 or 3 spine-like teeth at the extreme tip). The Strumigenys head is similar to Odontomachus which lacks a postpetiole.
There are four species in the United States, and at least three of them are introduced. T. caespitum is common and widespread.
Recognition: Total length 1.75-4.25 mm. Body with cuticle thick and with an armored appearance; usually the cuticle strongly sculptured. Anterolateral portions of clypeus raised into a ridge in front of antennal sockets. Antenna with 11 or 12 segments, with an apical club of 3 segments. Frontal carina strongly developed in most species and reaching almost to the posterior border of the head, however, in some species including the common T. caespitum, the frontal carina ends before the level of the eyes. Mesosoma without dorsal sutures. Metanotal impression present or absent. Propodeum usually armed with teeth or spines. Petiole with an anterior peduncle, without a large ventral process. Sting with an apical or apicodorsal lamelliform appendage (this may be hard to see). Tibial spurs on mid and hind legs present or absent.
Flag like lamelliform appendage
Similar Genera: This genus is similar to many species in genus Myrmica which can be separated by: clypeus with longitudinal rugulae interrupted by posterior border of clypeus and not continuous with rugulae of rest of head; posterior lateral portions of clypeus that border the antennal insertions not forming a vertical ridge (there are two aberrant Myrmica (M. colax and M. rugiventris) from southwestern USA that have a clypeal structure as in Tetramorium but they can be recognized by conspicuous, fine longitudinal rugae on the basal third of the first gastric tergite); antennal club indistinct or absent; palpal formula 6,4 (4,3 in Tetramorium).
Most forms are recorded from the more humid areas??????????????????????????????????????????, though a few occur in arid sections. Nests are in the soil. The fungi on which the ants feed is grown on a substratum of plant particles and insect excrement.
Recognition: Monomorphic. Frontal carina expanded laterally to form a more or less conspicuous lobe, but not projecting laterally beyond antennal insertion. Antenna 11-segmented without a well defined club. With a carina near the inner border of the eye extending posteriorly. Propodeum frequently with teeth or spines. Entire dorsal surface of body conspicuously tuberculate; gaster tuberculate. Femur and tibia with small tubercles each bearing a short, curved hair.
Similar Genera: Acromyrmex: # of spines on dorsum of mesosoma, mono / poly
One Japanese species, V. emeryi, is well established in moist stream valleys of the western half of the District of Columbia (Cover, in Hölldobler & Wilson, 1990: 66).
Recognition: Clypeus with a pair of longitudinal carinae that do not form teeth on the anterior margin. Antenna 12-segmented with a 3-segmented club. In profile, dorsum of mesosoma flat, without sutures. Petiole without anterior peduncle and with a large, translucent, plate-like anteroventral process.
A single species of this Neotropical genus has been introduced into the United States. It nests in exposed soil, under cover of objects, or in wood. Attends honeydew excreting insects, can sting severely, and infests houses. It is called the little fire ant.
Recognition: Very small; total length about 1.5 mm. Brown to golden brown. Frontal carinae extending almost to the posterior border of the head. Antenna 11-segmented with a 3-segmented club; the terminal antennal segment is large, prominent, and considerably longer than the combined length of the preceding two segments. Lower margin of eye angulate. Humeri of pronotum angulate. Pronotum armed with long spines, closely placed basally. Petiolar node in profile subrectangular.
Similar Genera: The long frontal carinae are also found in genus Tetramorium which can be distinguished by: anterolateral portions of clypeus raised into a ridge in front of antennal sockets; sting with an apical or apicodorsal lamelliform appendage.
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Recognition: Small arboreal ants; total length less than 2 mm. Integument smooth or weakly sculptured. Anterior border of clypeus with median concavity that is sometimes flanked on either side by a tooth. Antenna 11-segmented; 3 segment club with terminal segment longer than combined lengths of preceding two segments. Metanotal region moderately to profoundly impressed, forming a trough between the promesonotum and the propodeum. Propodeum unarmed. Petiole in lateral view subcylindrical, the node absent or rudimentary. Femur enlarged.
In the Nearctic region, this is of the smaller subfamilies of ants, with most species found in the tropical regions of the world. Most of the Nearctic forms are either northern extensions of Neotropical taxa or have been introduced by commerce from other parts of the world. The Nearctic region has 31 species and subspecies in 13 genera. Most Nearctic species are infrequently encountered and are small cryptic foragers in the soil, leaf litter, and rotten logs. These are primitive ants that nest in small colonies of a few hundred individuals or less, mostly in soil or rotting wood. They are predaceous and carnivorous. Some species are solitary hunters that do not recruit nestmates to food sources - a primitive behavioral trait.
Recognition. The mesosoma is attached to the gaster by a single segment, the petiole. The gaster usually has a slight but distinct constriction between the first and second segments. (Exceptions: i) genus Discothyrea, the gaster is highly modified and the impression is weak or absent, but in these the gaster is strongly arched and the tip of the gaster is directed forward and downward ii) in Anochetus and Odontomachus the gaster is smooth and uniform, but the mandibles are long and straight and they are inserted in the middle of the anterior margin of the head.) The upper surface of the tip of the gaster (the pygidium) is rounded and lacks a row of spines or teeth on its outer and trailing edge. The sting is present although sometimes retracted and difficult to see.
This tropical genus is represented in the Nearctic region by a single species only recently found in Florida. These ants form small colonies with fewer than 100 workers and are predators on small invertebrates using their trap like mandibles to capture prey. They nest in rotten logs.
Recognition: The genus Anochetus is one of the most distinctive and easily recognized of all ants. Mandibles long and linear with 2 or 3 apical teeth arranged in a vertical series and at most denticles along the inner margin; mandibles inserted in the middle of the anterior margin of the head. Head widest in the forward third and narrowing both behind and in front of this bulge. The top, backside of the head uniformly colored and lacking apophyseal lines (dark, V-shaped lines). The upper front of the head usually smooth (sometimes with a weak groove).
Similar Genera: The shape of the head and form of the mandibles easily distinguish Anochetus from all genera other than Odontomachus. Anochetus can be separated from Odontomachus by generally smaller size and lack of apophyseal lines on the back of the head.
Only one apparently endemic species occurs in the United States. The colonies are small (fewer than 100 workers), and nests are usually found in soil under rocks or in rotten logs. Little is known of their biology, but they are believed to be subterranean foragers. The small spines on the outer tibiae of the middle legs are thought to improve traction as workers forage through narrow passages in soil or rotten wood (Shattuck, 1999. Australian Ants: 183).
Recognition: Length 2-4 mm. Mandible with a small, oval, pit-like depression on the dorsolateral surface near the insertion into the head. (This is best seen from below and to the side of the mandibles. Carefully adjusting the lighting may help highlight the small pit.) Frontal carinae close together posteriorly; anterior sections of frontal lobes and antennal insertions are very close together. Eye small. Tibia of the mid leg with spine-like bristles on outer surface. Mid and hind tibiae with two apical spurs: one large and pectinate and the other smaller and simple. Tarsal claw simple.
Similar Genera: The genera Cryptopone, Hypoponera, Pachycondyla, and Ponera have the same overall body shape, and they are often confused with each other. Cryptopone is unique within this group in having a small pit on the mandible near the insertion into the head and the tarsal segment of the middle leg has spine-like bristles.
This is a large cosmopolitan genus whose species can be quite common although often unnoticed. They are cryptic predators foraging in the soil and leaf litter. Some species reproduce partly or entirely by ergatoid (worker-like) queens. Five species.
Recognition: Length 2-4 mm. Palpal formula 1,1 (this is usually very hard to see). Eye very small; located distinctly anterior to the midlength of the head. (Nests sometimes contain ergatoid (worker-like) queens that do no have wings but have large eyes and ocelli.) Antennae 12 segmented the last 4 or 5 segments enlarged forming an indistinct club. Mesosoma with promesonotal and mesopropodeal sutures visible from above. Mid and hind tibia with a single pectinate (comb-like) spur. Subpetiolar process simple - without anterior fenestra (circular translucent window) and without a pair of small teeth pointing rearward. Tarsal segments of mid legs without short, stout bristles. Tarsal claws simple.
Similar Genera: The genera Cryptopone, Hypoponera, Pachycondyla, and Ponera have the same overall body shape, and they are often confused with each other. Genus Ponera is most similar to Hypoponera, but Ponera is unique in having the ventral portion of the petiole (subpetiolar process) with a circular, translucent window in the front and a pair of small teeth pointing rearward. Cryptopone has its tibia of the mid leg with spine-like bristles on outer surface, and mandible with a small, oval, pit-like depression on the dorsolateral surface near the insertion into the head. Pachycondyla has 2 tibial spurs on its mid and hind legs.
Only two species of this tropicopolitan genus occur in the United States. They both form small colonies in the soil and have ergatoid (worker-like) queens. Workers are predacious and, the two Nearctic species are believed to feed primarily on isopods although they have also been observed transporting a wolf spider back to the nest. The unusual shape of the clypeus may help in gripping large, slippery prey like isopods (Trager & Johnson, 1988: 30).
Recognition: Length 5-7 mm. Body slender. Limbs long and slender. Mandible elongate, shining, and slender, usually without conspicuous subapical teeth. Anterior margin of clypeus sharply triangular in form, its center projecting forward. Sockets of the antennal insertions close together, separated by less than the maximum diameter of a single socket. Antennal scape long, extending approximately one-third its length beyond the posterior corner of head. Eye large, prominent. Tarsal claws finely pectinate (comb-like).
Similar Genera: These distinctive looking ants can be immediately recognized by the shape of the clypeus and the pectinate tarsal claws.
This tropicopolitan genus has four species that reach the southern portions of the United States. Most colonies are small and are found in soil or in rotting logs and stumps. Workers forage singly and are predaceous and carnivorous. Three species.
Recognition: The genus Odontomachus is among the most distinctive and easily recognized of all ants. Total length 6-20 mm. Mandible long and straight; inserted in the middle of the anterior margin of the head; apex with 2 or 3 teeth arranged in a vertical series. Head widest in the forward third and narrowing both behind and in front of this bulge. The top, backside of the head has a pair of apophyseal lines (dark V-shaped lines) that converge at the top to form a distinct, sometimes shallow groove on the upper part of the front of the head. Scale of petiole always ending in a single acute point dorsally. Gaster usually without a constriction between the first and second segments (this is the only Nearctic genus in subfamily Ponerinae that lacks this constriction).
Similar Genera: The shape of the head and form of the mandibles easily distinguish Odontomachus from all genera other than Anochetus. Members of Anochetus usually have much smaller body size and always lack the pair of apophyseal lines on the backside of the head. Genus Amblyopone has similar mandibles but they lack the vertical series of 2 or 3 teeth at the apex and the mandibles are inserted at the anterolateral corners of the head. Additionally, Amblyopone has its petiole broadly attached to the gaster, and the gaster has a constriction between the first and second segments.
This large and diverse genus is found in the tropical and subtropical regions throughout the world. Only three species reach the United States. They nest in soil either in the open or under rocks and logs. Most species are general predators and scavengers. Some are specialized predators on termites, and one is known to harvest seeds (Brown, W.L. 2000: 60).
Recognition: Length 7-13 mm. Mandible triangular with long masticatory margins containing many small teeth. Frontal carinae converge posteriorly; toward the front they flare out to form distinct lateral lobes that (in frontal view) conceal the antennal insertions. Eye large. Mid and hind tibiae with two apical spurs (the outer spur often nor more than half as long as the inner); one spur pectinate and one simple. (Shattuck, 1999. Australian Ants).
This genus is found in tropical areas throughout the world. Only one species reaches the United States. They nest in soil, rotten wood, and hollow twigs in trees. Some species are specialized predators on termites, others specialize in adult beetles, and others may be general predators. They can inflict a severe sting.
Recognition: Frontal carinae well separated and subparallel posteriorly; anterior sections of the frontal lobes and the antennal insertions are widely separated by the broadly rounded or triangular posterior extension of the clypeus. Hind tibia with two apical spurs: one larger than the other both finely pectinate. Tarsal claw on mid and hind legs each with a submedian tooth. Dorsal surface of head and body without erect hairs. Body dull or feebly shining; bearing sparse, shallow punctures; entirely covered with very fine, appressed pubescence that gives the surface a pronounced grayish or silvery cast.
Similar Genera: The one Nearctic species is easily recognized. The two pectinate spurs on the hind leg immediately separate it from all other Nearctic ponerine genera.
The two North American species are quite common in forested areas where they nest in small colonies in rotten wood or stumps or in the soil beneath cover. The workers forage singly and are carnivorous (Smith, D.R. 1979: 1341).
Recognition: Length 2-4 mm. Palpal formula 2,2 (this is often very hard to see). Eye very small; located distinctly anterior to the midlength of the head. (Nests sometimes contain ergatoid (worker-like) queens that do not have wings. They will have large eyes and ocelli.) Antennae 12 segmented the last 4 or 5 segments enlarged forming an indistinct club. Mesosoma with promesonotal and mesopropodeal sutures visible from above. Subpetiolar process (the structure below the petiole) with anterior fenestra (circular translucent window) and a pair of small teeth pointing rearward. Tarsal segments of mid legs without short, stout bristles. Mid and hind tibia with a single pectinate (comb-like) spur. Tarsal claw simple.
Similar Genera: The genera Cryptopone, Hypoponera, Pachycondyla, and Ponera have the same overall body shape, and they are often confused with each other. Genus Ponera is most similar to Hypoponera