Genus Prenolepis (Formicinae)

• Prenolepis Mayr, G. 1861: 52 . Type species: Tapinoma nitens Mayr, by subsequent designation of Bingham, 1903: 325.

• OVERVIEW.   The one Nearctic species in this genus, Prenolepis imparis, 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. Interestingly enough their range does not extend into the far north as might be expected from their cold tolerance. These ants usually nest in the soil in exposed situations or occasionally under a rock. 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. Males and females overwinter in the nest and are among the first of ants to take their nuptial flights in the spring. This genus is questionably distinct from Paratrechina. The combination of Paratrechina and Prenolepis is apparently monophyletic based on characteristics of larvae, workers, males, and queens (Trager, 1984b: 53-54). Recent phylogenetic analysis (Fontenla, 2000. Caribb. J. Sci. 36: 76-86) shows Paratrechina longicornis (Latreille) to be a sister taxon of the more derived species of Prenolepis. Clearly, these genera are in need of taxonomic analysis. Furthermore, the validity of the subspecies of Prenolepis imparis is questionable, and they probably should be considered junior synonyms of Prenolepis imparis (S.P. Cover, personal communication).
• ZOOGEOGRAPHICAL REGIONS.  Neotropical, Nearctic, Palearctic, Oriental, Indo-Australian.


      
Photo of Prenolepis imparis (Say) from AZ, Yavapi Co.. Courtesy of Ant Web, U. of Calif. Davis


• 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.



Figure of Prenolepis imparis from Smith, M.R. 1965.


• 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. 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.

• SPECIES IDENTIFICATION.   Wheeler, W.M. 1930c could be used to separate the "subspecies", but it is doubtly that these subspecies will stand up to modern taxonomic analysis.
• TRIBE.  Plagiolepidini.
• REVISIONS.   Emery, 1893k: 635–637 (North American species) .— Emery, 1906b: 130–134.— Wheeler, W.M. 1930c: 1–26 .— Fontenla, 2000: 76–86 (Carribbean species, phylogenetic analysis) .
• TAXONOMY.   Smith, M.R. 1943e: 317 (diagnosis of m.) .— Smith, M.R. 1947f: 612–613, pl. 20, fig. 77 (description w., figure (lateral view) of w.) .— Creighton, 1950a: 410–415, pl. 52, figs. 1–4 .— Wheeler, G.C. & Wheeler, J. 1953c: 142 (larvae) .— Wu, J. & Wang, 1992a: 56 (abstract, in Chinese) .— Bolton, 1994: figs. 126, 127 (SEM (full face and lateral view) of w.) .— Xu, Z. 1995b: 337–341 (new species from China) .—Bolton, 2003: 276.
• ALL REFERENCES

• arizonica. Prenolepis imparis var. arizonica Wheeler, W.M. 1930c: 22 (w.q.m.) . [USA, AZ, (Huachuca Mts.); MCZ] Subspecies of imparis: Creighton, 1950a: 414.

• TAXONOMY. Creighton, 1950a: 413, 414 .
• MISCELLANEOUS. Van Pelt, 1983: table 1 (habitat and frequency in the Chisos Mts. Texas) .
• PHOTOS.

• coloradensis. Prenolepis imparis var. coloradensis Wheeler, W.M. 1930c: 22, fig. 4 (w.) . [USA, CO, El Paso Co.; AMNH, MCZ] Subspecies of imparis: Creighton, 1950a: 415.

• DISTRIBUTION. CO, NM.
• MISCELLANEOUS. Creighton, 1950a: 413, 415 .— Gregg, R.E. 1963: 496–498 .
• PHOTOS.

• imparis. Formica imparis Say, 1836: 287 (q.m.) . [USA, IN; No types known to exist.] Wheeler, W.M. 1930c: 16 (w.) . Combination in Prenolepis: Mayr, 1886d: 431. Current subspecies nominal plus arizonica, colimana, coloradensis, veracruzensis.
• wichita. Formica (Tapinoma) wichita Buckley, S.B. 1866: 169 (w.) . [USA, TX, (" northern"] Combination in Prenolepis: Mayr, 1886d: 431. Junior synonym of nitens: Mayr, 1886d: 431. Synonymy: Dalla Torre, 1893: 178; Wheeler, W.M. 1930c: 15 .
• americana. Prenolepis nitens var. americana Forel, 1891c: 94, pl. 3, fig. 4 (m.) . [USA] Synonymy: Dalla Torre, 1893: 178; Emery, 1893k: 635 .
• minuta. Prenolepis imparis var. minuta Emery, 1893k: 636 (w.m.) . [USA, DC] Wheeler, W.M. 1930c: 21 (q.) . Synonymy: Creighton, 1950a: 414 .
• testacea. Prenolepis imparis var. testacea Emery, 1893k: 636 (q.m.) . [USA, DC & VA] Wheeler, W.M. 1905j: 390 (w.) . Synonymy: Creighton, 1950a: 414 .
• pumila. Prenolepis imparis var. pumila Wheeler, W.M. 1930c: 21 (w.m.) . [USA, NC, Wake Co.] Synonymy: Creighton, 1950a: 414 .
• californica. Prenolepis imparis var. californica Wheeler, W.M. 1930c: 23, fig. 4 (w.q.m.) . [USA, CA, Santa Clara Co.] Subspecies of imparis: Creighton, 1950a: 414. Synonymy: Wheeler, G.C. & Wheeler, J. 1986g: 14 .

• DISTRIBUTION. Most of the USA. Southern Ontario. Mexico.
• NATURAL HISTORY. write this up based on Tschinkel, 1987 supplemented with Talbot, H&W.
• TAXONOMY. Wheeler, W.M. 1930c: 1–26, fig. 3, 4 (description w.q.m., figures (lateral view) w., distribution, extensive natural history, relationship to fossil forms) .— Eckert & Mallis, 1937: 27.— Cole, A.C. 1940b: 66, 67.— Wesson & Wesson, 1940: 100.— Smith, M.R. 1947f: pl. 20, fig. 77 (figure (lateral view) of w.) .— Creighton, 1950a: 413–414, pl. 52, figs. 1–4 (figure (lateral view) w.q.m., wing) .— Wheeler, G.C. & Wheeler, J. 1953c: 142–143 (larva) .— Smith, M.R. 1965: 78–89, fig. 43 (description w., figure (lateral view) w., natural history) .— Warren & Rouse, 1969: 54, 55 (diagnosis of w., brief natural history, distribution in AR) .
• MISCELLANEOUS. Smith, M.R. 1924c: 122.— Essig, 1926: 866.— Smith, M.R. 1928c: 278.— Dennis, 1941: 82–86.— Mallis, 1941: 77–78.— Talbot, 1943: 31–44 (nest census, trunk trails, territory) .— Talbot, 1943: 345–352 (response to temperature and humidity changes) .— Hess, 1958: 52–53, 55–57, 59, 63 (nest site) .— Carter, 1962b: 196 (habitat, distribution in NC) .— Van Pelt, 1963: 213 (altitude preferences in southern Blue Ridge Mtns. (VA, NC, GA)) .— Tarpley, 1965: 6 (nuptial flight) .— Lynch, Balinsky & Vail, 1980: 353–371 (natural history, mass recruitment, dominates baits, diet) .— Lynch, 1981: 183–198 (strong habitat preference for mature forests) .— Tschinkel, 1987: 143–164 (detailed natural history, colony life cycle, nest structure, nest census) .— Cokendolpher & Francke, 1990: 31 (distribution in TX) .
• PHOTOS.