Pogonomyrmex bolivianus Johnson NEW SPECIES

Holotype worker: BOLIVIA, La Paz: 45 mi S La Paz, 25 February 1951 (E.S. Ross & A.E. Michelbacher) [CASC]. Paratypes, same data as holotype: CASC (15w), RAJC (2w).

Worker

Diagnosis. The combination of: (1) striae covering anterior one-fifth to one-half of first gastral tergum, rest of tergum smooth and polished, strongly shining, (2) rugae on mesosoma wavy to moderately irregular, (3) superior propodeal spines consist of short, triangular, acuminate teeth, and (4) height of inferior propodeal spines greater than that of superior propodeal spines uniquely characterize this species.

Measurements (mm) - holotype (n = 12 paratypes). HL 1.54 (1.43-1.61); HW 1.66 (1.53-1.69); MOD 0.32 (0.31-0.35); OMD 0.42 (0.41-0.47); SL 1.16 (1.07-1.31); PNW 1.08 (1.06-1.18); HFL 1.57 (1.42-1.65); ML 1.87 (1.65-1.95); PW 0.40 (0.37-0.43); PPW 0.55 (0.54-0.69). Indices: SI 69.88 (66.46-77.51); CI 107.79 (100.64-110.00); OI 19.28 (18.45-22.88); HFI 94.58 (89.38-101.90).

Description. Head quadrate to wider than long (CI = 100.64-110.00); posterior margin flat in full-face view. Longitudinal cephalic rugae prominent; in full-face view, medial rugae diverging toward posterior corners of head; interrugal spaces lacking a beaded appearance, weakly to moderately granulate-punctate, weakly shining to shining. Vertex rugose; interrugal spaces weakly granulate, weakly shining to smoothy and shining. Anterior margin of clypeus moderately concave, dorsum with numerous suparallel longitudinal rugae. Mandible with six teeth; mandibular dorsum coarsely striate. MOD ranging from 0.19-0.25x HL. Eyes in profile situated slightly anterior to middle of head, OMD = 1.20-1.43x MOD. In full-face view, eyes protruding slightly beyond lateral margins of head. Antennal scapes (SI = 66.46-77.51) reaching posterior corners of head or failing to do so by less than length of basal funicular segment. Antennal scapes strongly striate, interrstriae moderately punctate, dull to weakly shining; basal flange well developed with carinate margin. Psammophore well developed.

Mesosomal profile weakly to moderately convex; all mesosomal surfaces with prominent widely spaced, wavy to irregular rugae. In dorsal view, pronotal humeri enlarged, weakly to moderately angulate. Promesonotal suture usually weakly to moderately impressed. Wavy to irregular longitudinal rugae on mesonotum continue onto pronotum, medial rugae continue to pronotal collar, lateral rugae diverging to humeri. Rugae on pronotal sides irregular, traversing ventrally or posteroventrally or weakly rugoreticulate. Irregular rugae on mesopleura angle posterodorsally; irregular transverse or oblique rugae on dorsum of propodeum traverse ventrally or anteroventrally on sides. Superior propodeal spines consist of short, triangular, acuminate teeth, spines connected by a weak to well-defined keel. Inferior propodeal spines moderately well developed, wider than high, triangular, narrowing to rounded to broadly rounded tip, height greater than length of superior spines. Propodeal spiracles narrowly ovate, facing posterad. Interrugal spaces on mesosoma weakly granulate-punctate, weakly shining to smooth and shining. Legs weakly coriarious, weakly shining.

Petiolar peduncle about as long as petiole, anteroventral margin with weakly developed rounded process. In side view, posterior surface of petiole weakly convex; petiolar node asymmetrical with anterior surface longer than posterior surface, apex subangulate to weakly rounded. In dorsal view, petiole longer than wide, sides subparallel, narrowest near posterior margin, anterior margin spatulate to broadly rounded. Sides and posterior surface of petiolar node with regular to wavy transverse rugae, or rugae occasionally oblique. Dorsum of postpetiole convex in side view; in dorsal view, widest near posterior margin, narrowing to anterior margin, width and length similar. Rugae on dorsum of postpetiole more dense and less coarse than those on posterior face of petiole, interrugal spaces on both surfaces weakly granulate, weakly shining to smooth and strongly shining. Longitudinal striae cover anterior one-fifth to one-half of first gastral tergum, rest of tergum smooth and polished, strongly shining.

Erect, mostly short to medium length, whitish pilosity moderately abundant on head, few hairs exceed 0.4-0.5x MOD. Moderately abundant suberect to semidecumbent pilosity on scape; abundant decumbent hairs on funicular segments. Legs with moderately abundant suberect to decumbent whitish to pale yellow setae. Rest of body with moderately dense, erect, medium-length, whitish to pale yellow setae. Head and mesosoma dark ferruginous orange to orangish-brown, mesosoma sometimes slightly darker than head; mandibles, antennae, legs, petiole, postpetiole, gaster dark brownish-orange.

Queen. Unknown.

Male. Unknown.

Additional material examined. None.

Etymology. The specific epithet, bolivianus, is derived from Ross & Michelbacher collecting the type series of workers in Bolivia.

Discussion. Pogonomyrmex bolivianus is not known to co-occur with any congeners, but note that very few series have been collected from the Bolivian altiplano. Regardless, P. bolivianus is easily diagnosed by longitudinal striae that only cover the anterior one-fifth to one-half of the first gastral tergum with the rest of the tergum smooth and polished, strongly shining. All congeners lack striae on the first gastral tergum or the striae cover most of the first gastral tergum with the rest of the tergum moderately to strongly coriarious, dull.