Pogonomyrmex leonis (Kusnezov, 1951) Johnson, 2021

Johnson, Robert A., 2021, A taxonomic revision of South American species of the seed-harvester ant genus Pogonomyrmex (Hymenoptera: Formicidae). Part II, Zootaxa 5033 (1), pp. 1-230 : 102-104

Pogonomyrmex leonis NEW STATUS

( Figure 47 )

Distribution—43C

Pogonomyrmex meridionalis leonis Kusnezov, 1951: 278 (worker). Syntypes examined: 4 workers [IFML], 1 worker [LACM]. ARGENTINA, Santa Cruz: Cañadón León, #5834 (N. Kusnezov leg.). LACM worker here designated LECTOTYPE [LACMENT273766].

Worker diagnosis. Workers of this species are uniquely characterized by the following combination of features: (1) basal area to anterior one-third or more of first gastral tergum moderately to strongly coriarious, weakly shining to dull; rest of segment smooth and shining, (2) posterior surface of petiolar node and dorsum of postpetiole with transverse to arcuate rugae, (3) interrugae on promesonotum moderately to strongly granulate, weakly shining to dull, (4) head ferruginous orange to orange-red; mesosoma, petiolar node, postpetiole blackish to black; gaster, legs orangish-brown to brownish-orange, (5) superior propodeal spines long, length> 0.7–0.8× the distance between their bases, (6) dorsum of promesonotum with> 12–15 closely spaced, weakly to strongly irregular, weakly developed, longitudinal rugae that continue to anterior margin of pronotum, (8) body size larger (HW> 1.90 mm; ML> 2.25 mm) ( Figure 47 ).

Measurements — lectotype. HL 1.80; HW 1.93; MOD 0.44; OMD 0.51; SL 1.23; PNW 1.24; HFL 1.78; ML 2.29; PW 0.46; PPW 0.67. Indices: SI 63.73; CI 107.22; OI 22.80; HFI 92.75.

Redescription. Head slightly wider than long (CI = 107.22), widest just posterior to eye; posterior margin flat in full-face view; sides of head anterior to eyes parallel to widening weakly anterad. Longitudinal rugae on cephalic dorsum prominent in full-face view, medial rugae diverging toward posterior corners of head. Interrugae on cephalic dorsum moderately to strongly granulate with a beaded appearance, dull to weakly shining; posterior corners rugose, interrugae weakly granulate, weakly shining. Anterior margin of clypeus moderately concave, dorsum with numerous subparallel, longitudinal rugae. Numerous long, curved, bristle-like, cream to light yellowish ammochaetae project from anterior margin of clypeus and basolateral margin of mandibles. Mandibles with six teeth; mandibular dorsum coarsely rugose. MOD ranging from 0.24–0.25× HL. In profile, eyes situated slightly anterior to middle of head, OMD = 1.15–1.16× MOD. In full-face view, eyes protruding slightly beyond lateral margins of head. Antennal scapes missing on lectotype. Psammophore well developed.

Mesosomal profile weakly convex; all mesosomal surfaces with subparallel, irregular rugae. In dorsal view, humeral shoulders of pronotum enlarged, dorsolateral margins weakly to moderately angulate. Dorsum of promesonotum with> 12–15 closely spaced, weakly to strongly irregular, weakly developed, longitudinal rugae that continue to anterior margin of pronotum; interrugae moderately to strongly granulate, weakly shining to dull. Irregular rugae on pronotal sides traverse ventrally; rugae on mesopleura angle posterodorsally; irregular transverse to oblique rugae on dorsum of propodeum traverse ventrally or anteroventrally on sides. Promesonotal suture lacking. Superior propodeal spines long, length> 0.7–0.8× the distance between their bases, well defined keel lacking between spines; inferior propodeal spines triangular, apex rounded, height about one-third the length of superior propodeal spines. Propodeal spiracles narrowly ovate facing posterad. Interrugae on mesosoma moderately to strongly granulate, dull to weakly shining. Legs weakly to moderately coriarious, weakly shining.

Peduncle of petiole about 0.8× as long as petiolar node, anteroventral margin with a expansion that continues posterad. In profile, posterior surface of petiolar node weakly convex; node asymmetrical with anterior surface notably shorter than posterior surface, apex angulate. In dorsal view, petiolar node longer than wide, widest near broadly rounded anterior margin, gradually narrowing posterad. Posterior surface of petiolar node with irregular, transverse or arcuate rugae. Dorsum of postpetiole convex in profile; in dorsal view, widest at or near posterior margin, narrowing to anterior margin, maximum width and length about equal. Wavy to irregular transverse to arcuate rugae on dorsum of postpetiole finer, denser than those on posterior surface of petiolar node; interrugae on posterior surface of petiolar node and dorsum of postpetiole smooth and shining to moderately coriarious, weakly shining. Basal area to anterior one-third or more of first gastral tergum moderately to strongly coriarious, weakly shining to dull, rest of segment smooth and shining.

Erect, short, cream-colored to yellowish pilosity moderately abundant on head. Moderately abundant suberect to semidecumbent pilosity on scape; abundant decumbent hairs on funicular segments. Legs with moderately abundant suberect cream-colored to yellowish setae. Mesosoma, petiolar node, postpetiole, gastral terga with moderately dense, erect, medium-length setae, hairs most dense on first gastral tergum, longest hairs about 0.5–0.7× MOD. Head ferruginous orange to orange-red; mesosoma, petiolar node, postpetiole blackish to black; gaster, legs orangish-brown to brownish-orange ( Figure 47 ).

Queen. Unknown.

Male. Unknown.

Additional material examined. None.

Etymology. The specific epithet, leonis , was named for Cañadón León, Santa Cruz Province, Argentina, where Kusnezov collected the syntype series. Cañadón León is now called Gobernador Gregores.

Discussion. Pogonomyrmex leonis likely co-occurs with P. sanmartini and P. vermiculatus and possibly with P. varicolor , and P. meridionalis . Pogonomyrmex leonis is distinguished from the first three species based on: (1) anterior portion of first gastral tergum moderately to strongly coriarious, rest of tergum smooth and shining, and (2) head ferruginous orange to orange-red; mesosoma, petiolar node, postpetiole blackish to black; gaster, legs orangish-brown to brownish-orange. Pogonomyrmex sanmartini , and P. varicolor have striae on the first gastral tergum and/or a different color pattern. Pogonomyrmex vermiculatus usually has a smooth and shining first gastral tergum or occasionally with striae along the base of the segment, but the anterior portion of the first gastral tergum is never coriarious as occurs in P. leonis . Pogonomyrmex leonis is most similar to P. meridionalis as both have a similar head shape and rugae patterning. However, P. leonis differs in having an orange-red head and black mesosoma and gaster, whereas P. meridionalis has a black head and mesosoma and a dark orangish gaster. This species was not collected by the author such that it appears to be uncommon and/or it occurs less accessible areas of central southern Patagonia .

Pogonomyrmex leonis is known only from the syntype series of five workers collected in central Santa Cruz , Argentina. The range of variation in the species is unknown given the few workers that were collected in the type series, but several morphological characters make this a distinct taxon. These characters include: (1) ferruginous orange to orange-red head and black mesosoma and gaster, (2)> 12–15 weak, irregular, longitudinal rugae on the promesonotum that continue to the anterior margin of the pronotum, (3) long superior propodeal spines, and (4) first gastral tergum moderately to strongly coriarious over the basal area to the anterior one-third or more of segment. Thus, I elevate P. leonis from subspecies to rank as a valid species .

Biology. Nothing is known about the biology of P. leonis as it is only known from the type series, which was collected about 70 years ago. The type locality is likely at an elevation of 300–600 m in the Patagonia Steppe ecoregion, as defined by Olson et al. (2001) ( Figure 43C ). This species most likely inhabits the vast, difficult to access central areas of Patagonia .

Figures

FIGURE 43. Geographic distribution of: (A) Pogonomyrmex intermedia, (B) P. lagunabravensis, and (C) P. leonis. The large black circle in each panel denotes the type locality.

FIGURE 47. Photographs of Pogonomyrmex leonis lectotype worker: (A) frontal view of head, (B) lateral view of body, and (C) dorsal view of body (LACMENT273766). Photographs by Shannon Hartman from www.AntWeb.org.