Liometopum luctuosum

Identification
Polymorphic, concolorous dark brown workers. The body is covered with a dense pubescence, a feature that partially explains the common name for ants in this genus - "velvety tree ants." It is possible to separate Liometopum luctuosum from Liometopum apiculatum by the presence of a metanotal suture that breaks up the dorsal mesosomal outline, the short and relatively sparse standing hairs on the top of the pronotum and their dark coloration. The largest workers of Liometopum apiculatum are distinctively larger than the largest sized luctuosum workers.

Distribution
This taxon was described from the United States.

Biology
Liometopum luctuosum nest under rocks, decaying logs and at the base of large trees. Colonies can be large and their abundant workforce can be quite noticeable due to their long foraging trails and constant activity. Foraging can be persistent throughout the day and night. This species is closely related and shares much in common with its co-occuring congener Liometopum apiculatum. Liometopum luctuosum is usually found at higher elevations (> 2000 m) but does occur in suitable habitat in lower elevation sites.

Nomenclature

 *  luctuosum. Liometopum apiculatum subsp. luctuosum Wheeler, W.M. 1905e: 325 (w.) U.S.A. Forel, 1914c: 619 (m.); Del Toro, et al. 2009: 321 (q.). Subspecies of occidentale: Creighton, 1950a: 339. Raised to species: Wheeler, G.C. & Wheeler, J. 1986g: 55; Mackay, Lowrie, et al. 1988: 102.