Adelomyrmex silvestrii

Adelomyrmex silvestrii is perhaps the most easily identified Adelomyrmex species, and it is widespread and abundant. It occurs in a wide variety of habitats, mature to secondary, wet to seasonally dry, and sea level to 1700 m elevation cloud forest. It can occur in over 70% of quantitative miniWinkler samples. In spite of its abundance, a nest has never been reported. (Longino 2012)

Identification
Distinguished from other species of the genus by the shape of postpetiole and anterior emargination of the gaster.

Key to Adelomyrmex of the New World mainland

Distribution
northern Mexico (Tamaulipas) to Costa Rica.

Distribution based on Regional Taxon Lists
Neotropical Region: Belize, Costa Rica, Guatemala, Honduras, Mexico, Nicaragua.

Castes
Males have yet to be collected.

Nomenclature

 *  silvestrii. Apsychomyrmex silvestrii Menozzi, 1931b: 270, fig.6 (w.) COSTA RICA. Combination in Adelomyrmex: Kempf, 1972a: 18. See also: Fernández, 2003b: 28.

Worker
Fernández (2003) - (n=8). HL 0.56-0.57 HW 0.52-0.54 SL 0.36-0.38 EL 0.05-0.06 WL 0.50-0.55 GL 0.74-0.77 TL 2.30-2.35 CI 94 SI 71-72.

Sides of head evenly convex. Mandibles with 5 teeth decreasing in size from the apical teeth. Basal margin of the mandible with the tooth feebly developed. Dorsum of clypeal plate with two curved ridges very closed, prolongued into frontal carinae. Eyes small, with less than 10 facets, most with 5–6 facets. Hypostomal tooth small but clearly visible in frontal oblique view. Promesonotum slightly convex to flat, with strong transversal fringe on anterior pronotal margin. Metanotal groove weak. Propodeum sloping with two spines long, stout, directed backwards and nearly horizontal. Petiole stout in profile, with feebly concave posterior side, ventral face convex with several transverse rugae, appearing as serrations in profile. Postpetiole high, campaniform with a ventral transverse ridge toothlike as seen in profile. In dorsal view and lateral view, postpetiole extending posteriorly over basal gaster, as a blunt point. Gaster with emarginate base and humeral angles. Dorsal surface of head, pronotum and mesonotum with coarse, longitudinal rugulae. Transverse rugae between propodeal spines and sides of petiole and postpetiole. Declivity face of propodeum from smooth to covered with transverse rugae. Mandibles, clypeal plate, legs, petiole, postpetiole and gaster shining. Meso and hind tibia with some long hairs. Hairs yellowish, long and sparse (most hairs about 0125 mm long, as long as basal width of apical flagelomere), more short and apressed on antennae and legs. Body black to dark brown or dark reddish, antennae and legs more lighter, brown to yellowish.

Queen
Similar to worker except for queen-specific characters of large compound eyes, ocelli, and enlarged mesosoma with queen-typical sclerites; pronotum smooth medially, reticulate rugose laterally; dorsal mesonotum mostly longitudinally rugose, weaker anteromedially; scutellum longitudinally rugose; katepisternum smooth and shining with thin strip of rugosity along posterior border; anepisternum and side of propodeum longitudinally rugose.