Pogonomyrmex striatinodis

Robert A. Johnson, 2015, A taxonomic revision of South American species of the seed-harvester ant genus Pogonomyrmex (Hymenoptera: Formicidae). Part I, Zootaxa 4029 (1), pp. 1-142 : 127-129

Pogonomyrmex striatinodis

( Figure 66)

Pogonomyrmex striatinodis Fernández & Palacio, 1998: 1650 , figs. 1–8 (worker). Holotype worker [UNCB] (not examined). COLOMBIA, Nariño: Municipio de Barbacoas, Corregimiento de Altaquer, Reserva Natural Privada Río Ñambí, 1200– 1400 m (Carlos Sarmiento leg., 14 July 1995). Paratypes examined, same data as holotype: 1 worker [FML], 1 worker, [LACM], 1 worker [NMW], 2 workers [USNM].

Worker. Diagnosis. Within the P. sylvestris- group, the combination of: (1) seven mandibular teeth, (2) eyes lacking hairs between ommatidia, (3) clypeus with prominent medial carina, and (4) in profile, anterior margin of postpetiole meeting helcium at a smooth continuous angle uniquely characterize this species ( Figure 66).

Measurements —(n = 2 + 3 paratypes). HL 1.75–1.91; HW 1.58–1.68; MOD 0.28–0.32; OMD 0.37–0.42; SL 1.40–1.71; PNW 1.06–1.17; HFL 2.08–2.59; ML 2.20–2.34; PW 0.29–0.31; PPW 0.53–0.55. Indices: SI 88.05– 103.01; CI 85.48–90.32; OI 16.67–19.28; HFI 130.82–156.97. See also Fernández and Palacio (1998).

Redescription. Head elongate (CI = 85.48–90.32), widest just posterior to eye; posterior margin weakly concave. Cephalic dorsum, sides, and vertex rugoreticulate. Cephalic interrugae smooth, shining to strongly shining. Anterior margin of clypeus weakly convex with medial tooth that continues as a medial carina on dorsum of clypeus, dorsal surface with several subparallel, longitudinal rugae. Mandible with seven teeth; mandibular dorsum coarsely rugose. Up to several moderately long, curved, bristle-like, yellowish hairs project from anterior margin of clypeus. Eyes small, MOD = 0.15–0.17x HL. In profile, eyes situated anterior to middle of head, OMD = 1.19–1.45x MOD; no hairs project from between ommatidia. Antennal scapes long (SI = 88.05–103.01), surpassing vertex by slightly less than length of basal funicular segment; entire scape with moderately coarse, longitudinal striae, dull. Basal flange of scape well-developed with carinate margin. Psammophore poorlydeveloped, consisting of numerous short to moderately long hairs (similar in length to slightly shorter than those on cephalic dorsum) scattered across ventral side of head.

Mesosomal profile strongly convex; all mesosomal surfaces rugoreticulate to vermiculate. Superior propodeal spines long, acuminate, bases not connected by well-defined keel, spines about the same length as distance between their bases. Inferior propodeal spines well-developed, acuminate, length similar to that of superior spines but with a wider base. Interrugae on mesosoma smooth, shining. Propodeal spiracles circular facing posterad. In profile, procoxae with very weak, irregular to discontinuous transverse rugae, weakly shining. Legs moderately coriarious, weakly shining.

Peduncle of petiole about 0.4x length of petiolar node, anteroventral margin with acuminate spine. In profile, petiolar node asymmetrical with anterior surface approximately one-third the length of posterior surface, apex forming acutely tipped crest or tooth elevated above posterior surface; posterior surface flattened; anterior surface smooth and shining to moderately coriarious, weakly shining; lateral surface smooth and shining anterad, posterior one-half to two-thirds with coarse vertical rugae. In dorsal view, petiolar node elongate (length>2.70x width), weakly convex posterad, nearly vertical near center, and concave anterad, anterior one-third narrowing to subangulate tip; posterior surface with moderately coarse transverse rugae, interrugae weakly to moderately granulate-punctate, weakly shining. Dorsum of postpetiole convex in profile, anterior margin curving gradually to meet helcium at a smooth, continuous angle; in dorsal view, nearly triangular, widest near posterior margin, narrowing to nearly straight anterior margin; dorsum weakly coriarious, shining to smooth and strongly shining. First gastral tergum weakly coriarious, shining to smooth and strongly shining.

Short to long, flexuous, yellowish hairs abundant on head; medium to long hairs abundant on mesosoma, petiolar node, postpetiole, and gastral terga; longest hairs on head and mesosoma>MOD. Scape with abundant medium to long suberect hairs; abundant decumbent hairs on funicular segments. Legs with moderately abundant, long, suberect setae. Head and mesosoma dark reddish-brown to dark brown; petiolar node, postpetiole, legs, gaster slightly lighter orangish-brown ( Figure 66).

Queen. Unknown .

Male. Unknown .

Additional material examined. ECUADOR: Pichincha: Mindo, 1525 m, Nov 6, 2004 & Aug 27, 2005 (ALWC; RAJC); Santo Domingo: Reserva Otonga, Alluriquin-Las Damas Rd, 1209 m, Jun 5–10, 2014 (CISEC; RAJC; RIBNS) ( Figure 65 B).

Etymology. The specific epithet, striatinodis (from Latin —striãre = striate, and nõdus = node) refers to the transverse striae on the dorsolateral surfaces of the petiolar node.

Discussion. Pogonomyrmex striatinodis and P. sylvestris are the only congeners known to inhabit midelevation mesic forests. Pogonomyrmex striatinodis is diagnosed by: (1) lack of hairs between ommatidia, (2) seven mandibular teeth, and (3) in profile, anterior margin of postpetiole meeting helcium at a smooth, continuous angle; P. s t e f an i has: (1) several hairs between ommatidia, (2) six mandibular teeth, and (3) in profile, the anterior margin of the postpetiole is truncate and does not meet the helcium at a smooth, continuous angle. Pogonomyrmex striatinodis is separated from P. s t e f a ni by its sometimes weakly striate procoxae and absence of hairs between ommatidia; in P. stefani , the procoxae have prominent transverse striae and hairs are present between the ommatidia.

Pogonomyrmex naegelii might occur in open, drier habitats proximate to areas occupied P. striatinodis . Pogonomyrmex striatinodis is distinguished from P. naegelii by: (1) an elongate, triangular postpetiole, (2) in profile, the petiolar node is flattened with a crest or tooth on the anterior margin that is elevated above the posterior surface, and (3) head and mesosoma with numerous, long, flexuous hairs (longest hairs>MOD). In P. na e g el i i: (1) the postpetiole is nearly globular with length and width similar, (2) in profile, the petiolar node is convex and lacks a crest or tooth on the anterior margin, and (3) head and mesosoma have numerous short, relatively stiff hairs (longest hairs shorter than MOD). Pogonomyrmex striatinodis might also occur in areas proximate to P. theresiae ; P. striatinodis lacks a well-developed psammophore and has long superior and inferior propodeal spines, whereas P. theresiae has a well-developed psammophore and lacks superior and inferior propodeal spines.

Biology. See discussion under P. stefani .