Pogonomyrmex marcusi Kusnezov

Pogonomyrmex marcusi Kusnezov, 1951: 260, fig. 13a (worker, in key). Syntypes examined: 1 worker [MCZ], 1 worker [FML – not

examined], 3 workers [USNM], Cochabamba, Bolivia; Marcus, 1953; 46, figs. 30-38 (larvae); Kusnezov, 1954: 83, figs.

1-4 (queen, male). See also Marcus and Marcus, 1951: fig. 8; Wheeler & Wheeler, 1960: 3.

Lectotype designation. A syntype is designated as the lectotype of P. marcusi in order to stabilize the identity of this taxon. The identity of the specimen is indicated by a label and the specimen is deposited at MCZ. High resolution photographs of the lectotype are available at ANTWEB (http://www.antweb.org/).

Worker

Diagnosis. Pogonomyrmex marcusi is separated from other species in the P. coarctatus-group based on the following combination of characters: cephalic rugae covering most of head, areas lacking rugae shining to strongly shining; vertex smooth and strongly shining; in side view, lateral lobe of clypeus slightly enlarged; interrugal spaces on mesosoma smooth, strongly shining; inferior propodeal spine broader than long, apex bluntly angulate to acute; bicolored, head reddish-orange, first gastric tergite reddish-brown, rest of body reddish-orange to reddish-black.

Measurements (mm) - lectotype (n = 12). HL 2.04 (1.88-2.24); HW 2.21 (1.91-2.33); MOD 0.43 (0.38-0.44); OMD 0.47 (0.39-0.48); SL 1.33 (1.10-1.55); PNW 1.44 (1.14-1.36); HFL 1.93 (1.69-2.15); ML 2.48 (2.20-2.75); PW 0.53 (0.44-0.52); PPW 0.69 (0.59-0.69). Indices: SI 60.18 (57.59-70.92); CI 108.33 (100.000-110.00); OI 19.46 (18.03-20.95); HFI 87.33 (83.18-95.13).

Description. Monomorphic, head quadrate to more broad than long (CI = 100.00-110.00), broadest just posterior to eye, posterior margin flat to slightly concave in full-face view. Longitudinal cephalic rugae very fine and dense, usually covering only part of head, width of rugae and interrugae similar; in full-face view median rugae not diverging toward posterior corners of head. Vertex smooth, strongly shining. Cephalic interrugal spaces and most of dorsum of head strongly shining. Anterior margin of clypeus flat to slightly concave; dorsal surface with several moderately coarse subparallel longitudinal, oblique, or arc-shaped rugae. In side view, lateral lobe of clypeus usually slightly enlarged and elevated. Numerous long, curved, bristle-like, yellowish macrochaetae projecting from anterior margin of clypeus and underside of mandibles. Mandible with six teeth; mandibular dorsum strongly striated. MOD ranging from 0.18–0.22x HL. Eyes in profile situated anterior to middle of head, OMD = 0.88–1.18x MOD. Antennal scapes short (SI = 57.59-70.92), extending beyond posterior margin of eye by less than length of first two funicular segments. Antennal scapes smooth and shining; basal flange well developed with carinate margin. Psammophore moderately well developed.

Mesosomal profile slightly to distinctly convex. In dorsal view, humeral portion of pronotum slightly rounded to knoblike. All mesosomal surfaces with prominent coarse, subparallel, slightly wavy to irregular, widely spaced rugae. Dorsum of promesonotum with longitudinal rugae that diverge anteriorly toward humeral angles; transverse rugae on anterior face of pronotum continue obliquely or ventrally on pronotal sides; rugae on mesopleura angle to posterior or posteriodorsally. Propodeal spines long, strongly tapered, with acute tips, connected by a well-defined keel; spine length slightly less than width between their bases; regular to slightly wavy transverse rugae on propodeal dorsum traverse ventrally or anterioventrally on sides. Inferior propodeal spine broader than long, apex bluntly angulate to acute. Propodeal spiracles narrowly ovate. Interrugal spaces on mesosoma smooth, strongly shining. Legs smooth and strongly shining to weakly granulate, sub-shining.

Petiolar peduncle long, ventral surface with a broadly rounded process. In side view, dorsum of petiole slightly convex; petiolar node asymmetrical with anterior surface notably shorter than posterior surface, apex of node rounded to ovate. In dorsal view, petiole longer than broad, sides subparallel, slightly wider near middle, tapering to a spatulate anterior margin. Sides and dorsum of petiole with coarse, wavy to irregular transverse, oblique, or longitudinal rugae. Dorsum of postpetiole convex in profile; in dorsal view, widest near posterior margin, tapering to anterior margin, maximum width about equal to length. Regular to wavy, weak to moderately coarse transverse rugae on dorsum of postpetiole, sometimes weakening or lacking near anterior margin; interrugal spaces on petiole and postpetiole smooth to moderately granulate, sub-shining to shining. Dorsum of gaster smooth and strongly shining.

Erect white to yellowish pilosity sparsely to moderately abundant on head, mostly similar in length and arising from foveae; longest hairs not exceeding MOD, few exceeding 0.5x MOD. Moderately abundant suberect pilosity on scape; abundant decumbent hairs on funicular segments. Legs with moderately abundant suberect to decumbent setae. Mesosoma with moderately dense erect setae that are mostly similar in length, longest approaching MOD; petiole, postpetiole, and first gastric segment with moderately dense erect setae that are mostly similar in length, longest notably shorter than MOD; long hairs on margins of posterior gastric tergites often longer than MOD. Head reddish-orange, first gastric tergite reddish-brown, rest of body reddish-orange to reddish-black.

Queen

Diagnosis. As in worker diagnosis, but with caste-specific morphology of the mesosoma related to wing-bearing, presence of small ocelli on head, and as illustrated in Figure 10. Queens are also large (HW = 2.91 mm).

Measurements (mm) - (n = 1). HL 2.74; HW 2.91; MOD 0.56; OMD 0.63; SL 1.61; PNW 2.06; HFL 2.43; ML 3.35; PW 0.87; PPW 1.17. Indices: SI 55.33; CI 106.20; OI 19.24; HFI 83.51.

Male

Diagnosis.

Measurements (mm) - (n = 1). HL 1.69; HW 1.77; MOD 0.54; OMD 0.31; SL 0.45; HFL 2.09; ML 2.97; PW 0.63; PPW 0.78. Indices: SI 25.42; CI 104.73; OI 30.51; HFI 118.08.

Additional material examined. BOLIVIA: Cochabamba: Cochabamba.

Etymology. Kuznezov named this species after Dr. Harry Marcus, who apparently collected the syntypes and studied the ecology of this species. Kusnezov described P. marcusi in a key in his revision of the Pogonomyrmex of Argentina (Kusnezov, 1951), but he did not describe all three castes until Kusnezov (1954). During the interim, Marcus had completed two studies on the ecology of P. marcusi (Marcus, 1953; Marcus & Marcus, 1951).

Discussion

Pogonomyrmex marcusi is not known to co-occur with any P. coarctatus-group species (or any other species of Pogonomyrmex). Pogonomyrmex marcusi is easily distinguished from other species in the P. coarctatus-group using characters given in the key.