Strumigenys biolleyi

Nests on the forest floor, in dead wood, rotten twigs, and under loose bark. Workers forage nocturnally (Longino, Ants of Costa Rica).

Identification
Bolton (2000) - A member of the mandibularis complex in the Strumigenys mandibularis-group. S. biolleyi is the most variable species in the mandibularis complex and was discussed in detail by Brown (1953e). The form of the lamella on the propodeal declivity, seen in profile, is diagnostic of the species: no other has a lobe or tooth at the base of the declivity whilst lacking a more dorsally situated lobe or tooth. One species, Strumigenys hemidisca, has a simple lamella on the declivity that lacks any form of prominence either dorsally or basally. All others have some form of lobe or tooth both dorsally and basally on the declivity, even though these may sometimes be closely approximated and linked by a fairly broad lamella.

This species, like Strumigenys smithii, Strumigenys prospiciens and other members of the mandibularis series, possesses a small but distinct and acute intercalary tooth between the largest teeth of the apical mandibular fork, and two strong spiniform preapical teeth. In size, general proportions and facies, biolleyi closely resembles smithii and prospiciens, but differs from both in the shape of the propodeal lamellae and, less strikingly, in having relatively slightly more slender mandibular shafts. In closely related species, each propodeal lamella forms an upper and a lower tooth or distinct angles separated by an excision or concavity (except in Strumigenys hemidisca). In S. biolleyi, however, the upper (dorsal) of these angles is obsolete, represented by at most a feeble convexity, while the lower angle remains well developed as a salient triangular tooth, acute but with a usually blunt extremity. In the more distantly-related Strumigenys cordovensis, a similar condition occurs as an inconstant variation, but in biolleyi the propodeal form varies only within very narrow limits and appears to be characteristic.

Longino (Ants of Costa Rica) - Apical fork of mandible with a single intercalary tooth; mandible with two conspicuous preapical teeth; gastral dorsum smooth and shining; mandibles shorter than head; propodeal lamellae without dorsal teeth or angles (dorsal angle present in smithii), ventral angle present and prominent.

Distribution based on Regional Taxon Lists
Neotropical Region: Belize, Colombia, Costa Rica, Ecuador, Greater Antilles, Guatemala, Honduras, Jamaica, Mexico, Nicaragua, Panama.

Habitat
Occurs in wet forest habitats (Longino, Ants of Costa Rica).

Nomenclature

 *  biolleyi. Strumigenys biolleyi Forel, 1908b: 43 (w.) COSTA RICA. Brown, 1953f: 103 (q.); Wheeler, G.C. & Wheeler, J. 1960b: 26 (l.). Senior synonym of luctuosa, tridens: Brown, 1953f: 101. See also: Bolton, 2000: 530.
 * tridens. Strumigenys (Strumigenys) tridens Weber, 1934a: 29, fig. 3 (w.) PANAMA. Junior synonym of biolleyi: Brown, 1953f: 101.
 * luctuosa. Strumigenys (Strumigenys) luctuosa Menozzi, 1936c: 81, fig. 1 (w.) COSTA RICA. Junior synonym of biolleyi: Brown, 1953f: 101.

Longino (9 Nov 2013) - Strumigenys biolleyi is a species complex. There are separate montane and lowland forms, and turnover of forms with latitude. Three specimens have been DNA barcoded. Two are from montane sites in Nicaragua, cluster together, and match a common montane form from Costa Rica to Guatemala (and a similar montane form goes from Atitlan to Chiapas). This is probably true biolleyi; the holotype is from La Palma, a 1600m elevation site in Costa Rica. The other barcoded specimen is from a lowland rainforest site in Nicaragua. It is distinctive morphologically, and in the BOLD phenogram falls distant from the other two, separated by multiple other Strumigenys species. Lowland forms tend to be smaller, have reduced pilosity, and are more bicolored (red head and mesosoma, dark gaster). There are two synonyms under biolleyi, tridens from BCI, Panama, and luctuosa from La Caja, near San Jose, Costa Rica. Strumigenys tridens might match a lowland form, like the form at La Selva Biological Station. There is a distinct form I have from the Central Valley of Costa Rica and parapatric with the montane form in Monteverde, occurring in the moist forest transition zone between cloud forest and dry forest. This could be luctuosa.

Worker
Bolton (2000) - TL 2.6-3.3, HL 0.62-0.80, HW 0.52-0.66, CI 79-85, ML 0.37-0.52, MI 58-65, SL 0.43-0.60, SI 83-91, PW 0.33-0.42, AL 0.64-0.82 (30 measured).

Characters of mandibularis complex. Proximal preapical tooth located distal of the mandibular midlength. Outer margins of mandibles only weakly convex at full closure. Mesonotum usually without standing hairs, only rarely with a single pair present. Propodeum in profile with an acute lobe or triangular tooth at base of declivity; top of declivity without trace of an angular lobe or tooth. Disc of postpetiole broader than long, sculpture varying from smooth with peripheral weak sculpture to entirely reticulate-punctate, with all intermediate stages. Fine hairs on first gastral tergite usually confined to basal half, sometimes restricted to a single basal transverse row; hairs more extensive in some populations, especially more darkly coloured forms, where they may arise over the entire sclerite. Basigastral costulae usually absent, at most with minute vestiges immediately behind the limbus.

Type Material
Bolton (2000) - Holotype worker, COSTA RICA: La Palma, 1600 m. (P. Biolley) [examined].