Temnothorax silvestrii

An arboreal species that prefers to nest in evergreen oaks, particularly Quercus emory.. Like most arboreal ants that nest in Arizona, it nests in good sized limbs rather than twigs. The colonies are comparatively small. They contain from 50 to 70 workers with a single queen. (Creighton 1953)

Identification
Mackay (2000) - This species is yellow brown in color with a 12-segmented antenna. The head is completely and coarsely punctate, with fine rugae interspersed among the punctures, The top of the mesosoma and petiolar node have similar sculpture. The side of the mesosoma, side of the petiole and entire postpetiole are similarly punctate, with reduced extensive rugae when compared to the top of the mesosoma. The entire dorsum of the first tergum is evenly, but finely punctate. The petiolar spines are sharp and well developed. The peduncle of the petiole is elongate and the top of the node is truncate and square in shape. All of the femora, especially the hind femur, are incrassate. The maxillary palp has 5 segments, the labial palp 3 segments, the mandible has 5 teeth.

The reticulo-punctate disc of the first gastral tergite separates this species from all others except Temnothorax hispidus and Temnothorax obliquicanthus, and should separate it from the unknown workers of Temnothorax peninsularis. It differs from Temnothorax hispidus in that the propodeal spines are well developed and the hind femora are greatly thickened. It differs from Temnothorax obliquicanthus in that the eye is normal in shape and the petiolar node is very blunt in profile. It is most similar to Temnothorax smithi. but can be easily separated on the basis of the distribution (Arizona, Temnothorax smithi is found in eastern US), 12-segmented antenna (11-segmented in Temnothorax smithi) and by the rough sculpturing on the surface of the gaster (smooth and glossy in Temnothorax smithi). Creighton (1953) considered it to be closely related to Temnothorax bradleyi and Temnothorax smithi and provides characters to separate them.

Distribution
United States: southern Arizona.

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

Habitat
Oak forests.

Abundance
Only known from a few collections.

Nomenclature

 *  silvestrii. Tetramorium silvestrii Santschi, 1911d: 6 (w.) U.S.A. Creighton, 1953f: 5 (q.m.). Combination in Leptothorax: Santschi, 1922a: 68; in L. (Myrafant): Smith, D.R. 1979: 1395; in Temnothorax: Bolton, 2003: 272. See also: Mackay, 2000: 407.

Worker
Long. 3,2-3,4 mil. Jaune pale, mat. pilosite jaune dressee et coupee ras a, la facon des Leptothorax, plus courte sur la tete et l'abdomen remplacee sur les pattes et l'abdomen par une pubescence tres courte.

Devant de la tete ridee en long, ride-reticulee sur les cotes avec un fond finement ponctue. Clypeus assez fortement strie en long. Mandibules plus finement striees. Thorax rugueux, plus grossierement ride-reticule que la tete sauf entre les epines et sur un espace situe au milieu du dos ou predomine la ponctuation fondamentale. Pedicule rugueux. Premier segment abdominal finement reticule ponctue, les autres lisses.

Tete rectangulaire bien plus longue que large, yeux bormbes au milieu de ses cotes. Cretes frontales courtes non prolongees, aire frontale lisse, triangulaire, presque aussi longues que les cretes. Clypeus bombe non carene. Mandibules armees d' une dent apicale assez forte suivie de 4-6 denticules espaces. Antennes de 12 articles massue allongee dont Ie 2eme article est bien plus de deux fois plus long que large. Profil du thorax rectiligne un peu abaisse dans son tiers anterieur. Suture promesonotale assez distincte, la mesoepinotale effacee. Epines sensiblement plus longues que l'intervale de leur base, dirigees en arriere et en haut, divergeantes. Premier article du pedicule d' un quart plus long que haut avec un noeud cubique un peu arrondi en avant bien plus long que est suivant qui est environ d'un tiers plus large en ovale transversal. Premier segment de l'abdomen assez rectangulaire avec son bord anterieur legerement echancre.

Type Material
Creighton (1953) - samples sent to the Natural History Museum in Basel were compared to the single remaining type, which was from Santschi's collection. The type locality is given as Tucson but is more likely one of the near-by canyons in the Santa Catalina Mountains. Colonies have not been found below 3500 feet nor does the insect occur in the open desert, which would rule out this species' occurrence in Tucson."

Etymology
Patronym. Named after the Professor Filippo Silvestri.