Temnothorax bison

Despite multiple collections, very little is known about the biology of Temnothorax bison It appears to inhabit low-to-mid elevation tropical dry forest or xeric scrub habitats and forage terrestrially, much like its close relative, Temnothorax pergandei. (Prebus 2021)

Identification
Prebus (2021) - Temnothorax bison can be separated from all other species in the salvini clade by the following character combination: promesonotum evenly convex; metanotal groove deeply impressed and propodeum depressed below the level of the promesonotum; propodeal spines absent: dorsal face of propodeum transitioning evenly in to the propodeal declivity; in profile view, postpetiole bulging anterodorsally and flat posterodorsally; in dorsal view, petiolar node 1.3 to 1.6 times as broad as caudal cylinder; integument predominantly dark brown; setae on head, mesosoma, legs, waist segments and gaster erect, moderately long, abundant and tapering.

Similar species: this striking species is difficult to confuse with any other species in Temnothorax, except the closely related Temnothorax pergandei. The absence of propodeal teeth, the structure of the postpetiole, which is evenly convex dorsally in T. pergandei, and the relative width of the petiolar node in dorsal view (1.1 to 1.3 times as broad as the caudal cylinder in T. pergandei) will separate the two species.

Distribution
Low-to-mid elevations, southern Mexico to Nicaragua.

Distribution based on Regional Taxon Lists
Neotropical Region: Guatemala, Mexico, Nicaragua.

Nomenclature

 * . Temnothorax bison Prebus, 2021: 236, figs. 127A, 128 (w.) GUATEMALA.

Worker
(n = 8): SL = 0.535-0.675 (0.596); FRS = 0.171-0.244 (0.214); CW = 0.602-0.748 (0.678); CWb = 0.548-0.686 (0.627); PoOC = 0.229-0.282 (0.253); CL = 0.651-0.783 (0.710); EL = 0.158-0.207 (0.184); EW = 0.114-0.136 (0.124); MD = 0.143-0.178 (0.158); WL = 0.816-0.990 (0.901); SPST = 0.119-0.158 (0.141); MPST = 0.242-0.336 (0.300); PEL = 0.311-0.413 (0.366); NOL = 0.196-0.227 (0.211); NOH = 0.094-0.129 (0.112); PEH = 0.175-0.239 (0.209); PPL = 0.156-0.193 (0.173); PPH = 0.217-0.278 (0.248); PW = 0.395-0.513 (0.450); SBPA = n/a; SPTI = 0.163-0.211 (0.186); PEW = 0.141-0.176 (0.161); PNW = 0.197-0.282 (0.238); PPW = 0.234-0.314 (0.270); HFL = 0.555-0.732 (0.648); HFWmax = 0.126-0.157 (0.141); HFWmin = 0.046-0.060 (0.052); CS = 0.874-1.069 (0.982); ES = 0.215-0.273 (0.246); SI = 87-99 (95); OI = 23-27 (25); CI = 84-92 (88); WLI = 141-150 (144); SBI = n/a; PSI = 14-18 (16); PWI = 149-184 (167); PLI = 194-232 (212); NI = 167-209 (189); PNWI = 125-164 (147); NLI = 53-63 (58); FI = 254-292 (275).

In full-face view, head subquadrate, longer than broad (CI 84-92). Mandibles densely striate but shining and armed with five teeth: the apical-most well developed and acute, followed by a less developed preapical tooth and three equally developed smaller teeth. Anterior clypeal margin weakly convex medially. Antennal scapes very long: when fully retracted, surpassing the posterior margin of the head capsule by about two times the maximum width of the scape (SI 87-99). Antennae 12-segmented; antennal club of composed of three segments, with the apical-most segment as long as the preceding two in combination. Frontal carinae short, extending past the antennal toruli by about one and a half times the maximum width of the antennal scape. Compound eyes moderately protruding past the lateral margins of the head capsule. Lateral margin of head weakly convex, forming a continuous arc from the mandibular insertions to the posterior margin of the head. Posterior head margin weakly convex, rounding evenly into the lateral margins.

In profile view, compound eyes elongate ovular and moderately large (OI 23-27), with 11 ommatidia in longest row. Pronotal declivity indistinct, neck and anterior face of pronotum forming a ~120° angle. Mesosoma with promesonotum forming an even convexity; the propodeum depressed below the level of the promesonotum and dorsally concave. Promesonotal suture extending from the posterior margin of the procoxal insertion to the mesothoracic spiracle, which is moderately well developed, then continuing to the dorsal surface as a very weak sulcus. Metanotal groove visible as a disruption of the sculpture laterally from where it arises between the mid- and hind coxae to where it ends in the poorly developed metathoracic spiracle, which is nearly indistinguishable against the ground sculpture; continuing dorsally as a distinct sulcus. Propodeal spiracle well developed, directed posterolaterally, and separated from the propodeal declivity by about three spiracle diameters. Propodeal spines absent, but with a cuticular flange extending from the propodeal dorsum to the propodeal lobes in their place. Propodeal declivity flat, forming a rounded ~100° angle with propodeal dorsum. Propodeal lobes rounded and weakly developed. Metapleural gland bulla moderately large, extending from the metacoxal insertion two thirds of the way to the propodeal spiracle. Petiole long (PLI 194-232), without tubercles anterodorsally. Subpetiolar process in the form of a small, triangular, blunt tooth, which continues as a low carina to the caudal cylinder; ventral margin of petiole posterior to the subpetiolar process strongly concave. Petiolar peduncle moderately long: comprising about half the length of the petiole. Petiolar node cuneiform but rounded dorsally: transition between peduncle and node marked by a rounded angle of ~150°, resulting in a weakly concave anterior node face; anterior face forming a broadly rounded ~60° angle with the posterior face; caudal cylinder short, about half the maximum width of the antennal scape. Postpetiole weakly convex anteriorly, rounding evenly into the dorsal face, which bulges strongly before flattening posteriorly; lobed ventrally.

In dorsal view, humeri weakly developed: evenly rounded and wider than the rest of the mesosoma, but not distinct from it; mesothoracic spiracles weakly protruding past the lateral margins of the mesosoma, visible as slight angles where the pronotum meets the mesonotum. Promesonotal suture visible as a weak sulcus. Metanotal strongly impressed, distinctly dividing the promesonotum from the propodeum. Propodeal spines absent, but flanges diverging at the apex of the propodeal dorsum. Petiolar peduncle with spiracles weakly protruding past the lateral margins, but not noticeably constricted anterior to them. Petiolar node, when viewed posterodorsally, trapezoidal and apically broadened, the apex weakly convex; caudal cylinder narrower than the apex of the node. Postpetiole narrow (PWI 149-184) and trapezoidal: widest anteriorly. Anterior margin of the postpetiole weakly convex and meeting the lateral margins at a rounded angle; lateral margins converge moderately to the angulate posterior corners; posterior margin broadly concave. Metafemur moderately incrassate (FI 254-292).

Sculpture: median clypeal carina present, extending posteriorly to the level of the anterior margins of the antennal insertions. Lateral clypeal lobes with additional, weaker carinae; ground sculpture smooth and shining. Antennal scapes shining through weak coriarious ground sculpture. Cephalic dorsum predominantly coriarious, with costulae flanking the frontal carinae; concentric costulae surrounding the antennal insertions, extending from the apices of the frontal carinae, to the anterior margins of the lateral clypeal lobes. Lateral surfaces of head with weak coriarious sculpture posterior to the compound eye, denser coriarious sculpture surrounding the compound eye, and stronger costulae between the compound eye and the mandibular insertion. Ventral surface of head smooth and shining. Pronotal neck areolate. Lateral surface of the pronotum areolate-coriarious on the anterior third, otherwise smooth and shining. Lateral face of the propodeum, meso- and metapleurae predominantly costate, over areolate ground sculpture; area around propodeal spiracle finely areolate. Propodeal declivity smooth and shining. Dorsal surface of promesonotum coriarious. Dorsum of propodeum strongly rugose. Femora smooth and shining. Petiole smooth and shining ventrally; node weakly coriarious; dorsum of peduncle finely areolate. Postpetiole weakly coriarious. First gastral tergite weakly coriarious; first gastral sternite smooth and shining. Spectral iridescence absent.

Setae: antennal scapes and funiculi with moderately long, decumbent pilosity. Dorsum of the head, pronotum, waist segments, and gaster with moderately abundant, erect, tapering setae, the longest of which are about the length of the compound eye. The head bears ~40, mesosoma ~38, petiole ~14, postpetiole ~20, and first gastral tergite ~60 setae. Pubescence is long, coarse, difficult to distinguish from the setae, and present over the entire body except for the ventral surface of the petiole.

Color: predominantly dark brown, with mandibles, antennae, tibiae and tarsi testaceous.

Type Material
Holotype worker: GUATEMALA: Zacapa: Zacapa, finca near University Landivar campus,, 200 m, 18-21 June 2015, Z. Falin # GUATIF15-188, dry thorn scrub forest, flight intercept trap (CASENT0636947).

Paratype worker: same data as holotype, 1 worker (CASENT0636946).

Etymology
Morphological, in reference to the humpbacked appearance of the worker.