Leptothorax crassipilis Wheeler, W.M.


Leptothorax crassipilis head view  Leptothorax crassipilis side view
Small dark colored ants that are brown to brownish-black to black, with color varying across different parts of the body and between individuals. The gaster and head tend to be the darkest with the mesosoma and appendages exhibiting lighter coloration. Workers have relatively slender spines on the prododeum, mandibles with six teeth and 11 segmented antenna. In comparison to other Leptothorax found on the Navajo Reservation Leptothorax crassipilis have blunt, erect hairs on the head, thorax and pedicel that are longer, coarser and glistening white in color.
Small inconspicuous ants typically found nesting under rocks or downed wood. Wheeler's (1917) description hints at the biology of this species: "described from numerous specimens of all three phases taken from small colonies under stones in several localities (Manitou, Cheyenne Creek, Red Rock Canyon, Williams Canyon) near Colorado Springs." Gregg (1963) found colonies nesting under rocks and logs in conifer, oak and manzanita habitats in Colorado.
additional biology notes...
United States. Colorado, Wyoming, Utah, Nevada and Arizona.
Navajo Reservation Records
Samples being processed.
Additional Notes
Leptothorax ants will readily move their nesting location. Moglich (1978) showed that this process begins with a number of individual scout workers recruiting individual coworkers to visit a new nesting site via tandem running. If the new nesting location is amenable to enough recruited workers the process then shifts to a more intensive emigration. Workers stop using tandem running and begin carrying individual nestmates, brood and queens to the new nest location.
Leptothorax crassipilis, like many Leptothorax, is polygynous.
Morphological. A reference to the erect hairs on the body; crassus = thick + pilus = hair + is = with, having

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Original Combination - Leptothorax (Mychothorax) acervorum subsp. crassipilis - Wheeler, W.M. (1917).

the original species description for Leptothorax crassipilis (first page) species description for Leptothorax crassipilis (second page)

MCZ, AMNH - as reported by Creighton (1950)
Type Locality
Manitou, Colorado

Creighton, W. S. 1950. The ants of North America. Bulletin of the Museum of Comparative Zoology at Harvard University. 104:1-585.
Gregg, R. E. 1963. The ants of Colorado, with reference to their ecology, taxonomy, and geographic distribution. University of Colorado Press, Boulder.
Möglich, M. 1978. Social organization of nest emigration in Leptothorax (Hym., Form.). Insectes Sociaux. 25:205-225.
Wheeler, W. M. 1917. The mountain ants of western North America. Proceedings of the American Academy of Arts and Sciences. 52:457-569.

A note about these publications. The literature cited here is not meant to be an exhaustive list of papers published about this species.

Page authored by David Lubertazzi and Gary Alpert

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