Temnothorax rugosus

The type series was collected in a trap baited with Vienna sausage, placed in oak trees, about 2-meter height. The habitat was a very steep, south-facing slope of a mountain, covered with oak trees. The specimens were collected within 20 meters distant from one another. (Mackay 2000)

Identification
Mackay (2000) - A member of the Temnothorax nitens species complex. This is a medium sized, light brown species with a 12-segmented antenna, in which the head and mesosoma are coarsely rugose. It is one of the few species in the subgenus which has a very lightly sculptured gaster, which is not always obvious. The hind femur is somewhat incrassate. The petiole is narrow as seen from above, with a laterally "pinched" node, the postpetiole has fine, longitudinal striae. This species may be related to Temnothorax silvestrii, with similar sculpturing on the gaster (note: the sculpturing is very fine and difficult to see in some specimens), and a thickened hind femur, but is easily distinguished as the apex of the petiolar node is rather sharp, not broad and blunt as in Temnothorax silvestrii. The top of the mesosoma of both species is rugose. The shape of the petiole (forming an acute peak where anterior face meets top of node) easily separates it. It is quite different from all of the other species with sculptured gasters. It is very distinct from Temnothorax maryanae (=Temnothorax nevadensis), and can be easily distinguished as the side of the pronotum is rugose, whereas the side of the pronotum of Temnothorax maryanae is punctate.

The sculpture on the gaster of the holotype is very obvious, that on the 2 paratypes is less obvious. The latter specimens could key to Temnothorax tricarinatus. Temnothorax rugosus differs in that the sculpture is much coarser, with the rugae on the head and dorsum of the mesosoma very well developed. The petiole is much narrower as seen from above, and pinched. The sculpture of the postpetiole is more coarsely sculptured, with costulae at least on the sides. The clypeus has several poorly developed carinae, not the 3 well developed carinae as in Temnothorax tricarinatus. Temnothorax rugosus could also be confused with Temnothorax texanus, but can be separated as the rugae on the dorsum of the postpetiole of Temnothorax texanus are transverse, whereas the rugae in the same position of Temnothorax rugosus are longitudinal.

Distribution
Mexico: Nuevo Leon.

Distribution based on Regional Taxon Lists
Nearctic Region: United States. Neotropical Region: Mexico.

Habitat
Oak forest (type collections).

Abundance
Only known from types.

Caste
Known only from the worker caste.

Nomenclature

 *  rugosus. Leptothorax (Myrafant) rugosus Mackay, W.P., 2000: 399, figs. 18, 160 (w.) MEXICO. Combination in Temnothorax: Bolton, 2003: 272.

Worker
Mandibles with 5 well defined teeth; anterior border of clypeus convex, clypeus with well developed medial carina and several lateral carinae; vertex concave; mesosoma with none of the sutures breaking surface, although area of mesopropodeal suture depressed; propodeal angles well developed, acute, nearly formed into spines, about half as long as distance between bases; petiole with dull spine on peduncle, directed anteriorly, anterior and posterior faces nearly straight, meeting at a distinct angle, petiolar node thus acute in profile; femora of all legs, especially posterior leg, thickened. Erect hairs scattered over surface, coarse and blunt, maximum length 0.05mm, absent from antennae and legs, which have decumbent hairs. Sculpture very rough, consisting of rugae on all surfaces except gaster, intrarugal spaces heavily punctate, gaster with very fine punctation, nearly smooth and shining.

Color: light brownish-yellow, gaster and top of head slightly darker.

Worker measurement (mm): HL 0.67-0.70, HVV 0.58-0.59, SL 0.49-0.50, EL 0.16-0.17, WL 0.82-0.83, PW 0.14-0.15, PL 0.19-0.23, PPW 0.27-0.28, PPL 0.18-0.19. Indices: CI 84-87, SI 71-73, PI 65-74, PPI 147-150.

Type Material
MEXICO, Nuevo Leon; EI Salto (Zaragosa), 10-vi-1988, 1415 meters, W. Mackay #11012-8 and #11012-10. Holotype worker, and two paratype workers.

Etymology
Morphological. "Name based on the rugose head and mesosoma."

References based on Global Ant Biodiversity Informatics

 * Dattilo W. et al. 2019. MEXICO ANTS: incidence and abundance along the Nearctic-Neotropical interface. Ecology https://doi.org/10.1002/ecy.2944
 * Vásquez-Bolaños M. 2011. Lista de especies de hormigas (Hymenoptera: Formicidae) para México. Dugesiana 18: 95-133