Formicidae, Hymenoptera, Insecta, Arthropoda, Animalia
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Identification
Minor worker: head length 0.52mm, head width 0.50mm, scape length 0.49mm, Webers length 0.64mm (n=1). Head flattened, subcordate behind; promesonotum evenly arched, mesonotal suture absent; propodeal spines nearly absent, reduced to tiny tubercles; face, mesosoma, and gaster smooth and shining; dorsal pilosity abundant, of moderate length, flexuous, some setae on mesosomal dorsum branched near apex, branches minute; color dark brown to clear orange. Perhaps indistinguishable from subarmata; propodeal spines slightly more developed in the few samples available.
Major worker: head length 1.45mm, head width 1.19mm, scape length 0.54mm (n=1). Face shiny, parallel longitudinal rugae between eye and frontal carinae, extending posteriorly about as far as scape extent, a few rugae mesad to frontal carinae, but median portion of face posterior to clypeus and remaining posterior portion of face smooth and shiny (longitudinal rugae extend across median portion of face in subarmata); hypostomal margin with robust pair of inner teeth, located about one third distance from midline to recessed teeth flanking mandibles (these teeth smaller in subarmata), and a stout, blunt median tooth (absent or very low in subarmata and synarmata); in side view, frontal carinae elevated, but more rounded, not as sharply produced as in subarmata and synarmata; dorsal pilosity abundant; head with abundant short setae projecting from sides of head in face view; color dark brown to yellow.
Similar species: subarmata, synarmata.
Range
Mexico (Chiapas), Costa Rica (type locality), Venezuela, Ecuador. Costa Rica: Cordillera de Tilar‡n, Meseta Central, Cordillera de Talamanca.
Natural History
This species occurs in disturbed habitats of mid to high elevation sites. It has been found in coffee farms and suburban areas in the Central Valley and in scrubby pasture edge on the dry Pacific slope just below Monteverde. Two collections have been from beneath stones. Bob Anderson collected the species at a high elevation site, 2500m, at Valle de Silencio in the southern Talamanca range. This collection is of very dark specimens, like the types.
Comments
I used to consider this species a potential synonym of subarmata. Examination of additional material has revealed patterns of variation that suggest distinct species. The abundant La Selva material of subarmata shows little variation and is very similar to material I have seen from Honduras, suggesting stability of these characters over distance. In contrast, the types of hasticeps from San Josˇ de Monta–a, a soldier collected from beneath a stone in INBioParque in Santo Domingo de Heredia, and a nest series from beneath a stone near Estacion Biologica Los Llanos west of Santa Elena (near Monteverde) share a set of characters distinct from La Selva subarmata. Consistent characters in the soldier are the larger inner teeth and the stout median tooth of the hypostomal margin, the smooth median portion of face posterior to clypeus, and more rounded frontal carinae in side view. The minor workers of the two species are extremely similar, but La Selva subarmata have the propodeal spines as little more than blunt angles or tubercles, while hasticeps have a more distinct spine, albeit very short. The color seems to vary dramatically. The types and Valle de Silencio specimens are dark brown, while the Santo Domingo and Monteverde material is light brown to yellow.
14 July 2010: I now have more material of this species, including many collections from baits at Nah‡, a mid-elevation site in eastern Chiapas. During a recent baiting session at the Los Llanos station near Monteverde (in second growth moist forest habitat on the Pacific slope, west of Santa Elena) I found what looked like two discrete forms at baits. One was the light-colored form figured above. The other was a dark brown form. The majors of the dark brown form also had slightly narrower heads. However, they had the sculpture of hasticeps (lacking medial longitudinal carinae between the frontal carinae) and the minor workers have minute propodeal spines (rather than the complete absence of spines seen in subarmata). Thus is remains unclear whether this is intraspecific or interspecific variation.
Page author:
John T. Longino, The Evergreen State College, Olympia WA 98505 USA. longinoj@evergreen.edu
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