Pogonomyrmex araucania, 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 : 39-45

Pogonomyrmex araucania NEW SPECIES

( Figures 15–17 )

Distribution— Figure 14B

Holotype worker [ MACN: CASENT0914128 ]: ARGENTINA, Neuquén: Departamento Aluminé , 4.8 km E Villa Pehuenia, 38 o 53.3’S 71 o 08.3’W, 3830’ (1160 m), 9 February 2011 (R.A. Johnson #4700) . Paratypes, same data as holotype: IFML (3 workers) , LACM (3 workers) , MACN (3 workers) , MCZC (3 workers) , MNNC (3 workers) , RAJC (20 workers, 1 alate queen), UCDC (3 workers) , USNM (3 workers) .

Worker diagnosis. Workers of this species are uniquely characterized by the following combination of features: (1) well developed psammophore, (2) first gastral tergum lacking striae, weakly to strongly coriarious along base or extending over anterior one-half of segment or with faint, barely visible, unincised striae on anterior one-third to one-half of segment, (3) posterior margin and usually posterior one-third or more of first gastral tergum smooth and shining to strongly shining, rarely weakly coriarious, (4) transverse rugae on posterior surface of petiolar node and dorsum of postpetiole, (5) head and mesosoma concolorous to nearly concolorous light to dark ferruginous orange to reddish-brown, (6) clypeus orangish to orangish-red, concolorous with adjacent cephalic dorsum, (7) legs and antennal scapes usually orangish-brown, occasionally brownish to blackish, (8) superior propodeal spines long, length> 0.6× the distance between their bases, (8) in profile, most hairs on dorsum of mesosoma <0.5× MOD and no longer than length of superior propodeal spines ( Figure 15 ).

Measurements — holotype (n = 12 paratypes). HL 1.63 (1.32–1.70); HW 1.65 (1.43–1.78); MOD 0.31 (0.30– 0.35); OMD 0.40 (0.34–0.45); SL 1.28 (1.06–1.36); PNW 1.09 (0.95–1.17); HFL 1.71 (1.30–1.81); ML 1.92 (1.62– 2.02); PW 0.41 (0.36–0.44); PPW 0.63 (0.51–0.63). Indices: SI 77.58 (73.29–81.33); CI 101.23 (98.03–108.33); OI 18.79 (19.66–23.33); HFI 103.64 (87.84–107.74).

Description. Head subquadrate to wider than long (CI = 98.03–108.33), broadest just posterior to eyes; posterior margin flat in full-face view. Longitudinal rugae on cephalic dorsum prominent, rugae usually becoming irregular or rugoreticulate-vermiculate posterior to eyes, especially along posterior margin. In full-face view, medial rugae usually diverging toward posterior corners of head. Posterior corners rugose, interrugae weakly to moderately granulate, weakly shining to dull, occasionally smooth and shining. Cephalic interrugae strongly granulate, dull, with a beaded appearance. Anterior margin of clypeus concave, dorsum with numerous subparallel, longitudinal rugae. Numerous long, curved, bristle-like, yellowish macrochaetae project from anterior margin of clypeus and basolateral margins of mandibles. Mandibles with six teeth; mandibular dorsum coarsely rugose. MOD ranging from 0.18–0.23× HL. In profile, eyes situated slightly anterior to middle of head, OMD = 0.97–1.37× MOD. In full-face view, eyes protruding slightly beyond lateral margins of head. Antennal scapes (SI = 73.29–81.33) reaching or just failing to reach posterior corners of head. Antennal scapes smooth and shining to moderately coriarious, weakly shining, often with weak longitudinal striae; basal flange moderately well developed, flattened, with carinate margin. Psammophore well developed.

Mesosomal profile weakly to moderately convex. All mesosomal surfaces with prominent, irregular rugae to rugoreticulate. In dorsal view, humeral shoulders of pronotum enlarged, anterolateral margins angulate. Promesonotal suture usually absent. Dorsum of mesonotum with strongly irregular, longitudinal rugae that diverge toward humeral shoulders of pronotum, anteromedial portion of pronotum rugoreticulate or anterad portion to all of pronotum and sometimes anterad portion of mesonotum rugoreticulate; pronotal sides rugoreticulate. Irregular rugae on mesopleura angle posterodorsally, secondary rugae usually present; irregular transverse to oblique rugae on dorsum of propodeum traverse anteroventrally onto mesopleura. Superior propodeal spines long, length> 0.6× the distance between their bases, spines connected by a well defined keel; inferior propodeal spines broader than high, apex weakly rounded to subangulate. Propodeal spiracles narrowly ovate facing posterad. Interrugae on mesosoma weakly to moderately granulate-punctate, weakly shining. Legs smooth and shining to weakly to moderately coriarious, weakly shining.

Peduncle of petiole about 0.8× long as petiolar node, anteroventral margin with a well developed rounded process that narrows posterad, then continues subparallel-parallel to dorsal margin to near posteroventral margin of petiolar node. In profile, posterior surface of petiolar node weakly convex, node asymmetrical with anterior surface shorter than posterior surface, apex subangulate to weakly rounded. In dorsal view, petiolar node longer than broad, widest near spatulate anterior margin, gradually tapering posterad. Posterior surface of petiolar node with regular to irregular, wavy or arcuate, transverse rugae. Dorsum of postpetiole convex in profile; in dorsal view, widest at or near posterior margin, tapering to anterior margin, maximum width and length about equal. Wavy to irregular transverse rugae on dorsum of postpetiole finer, denser than those on posterior surface of petiolar node, secondary rugae usually present, sometimes nearly rugoreticulate; interrugae on both surfaces weakly to moderately coriarious, weakly shining. First gastral tergum weakly to strongly coriarious along base to extending over anterior one-half of segment, sculpturing sometimes appearing as faint, barely visible, unincised striae on anterior one-third to one-half of segment; posterior margin and usually posterior one-third or more of first gastral tergum smooth and shining to strongly shining, rarely weakly coriarious.

Erect, short to medium-length, white pilosity moderately abundant on head, longest along posterior margin approximately 0.8× MOD. Moderately abundant suberect to semidecumbent pilosity on scape; abundant decumbent hairs on funicular segments. Legs with moderately abundant suberect to decumbent white setae. Mesosoma, petiolar node, postpetiole, gastral terga with moderately dense, erect, medium-length, white setae. In profile, most hairs <0.5× MOD and no longer than length of superior propodeal spines. Head and mesosoma concolorous to nearly concolorous light to dark ferruginous orange to reddish-brown; legs and antennal scapes usually orangish-brown, occasionally brownish to blackish; gaster dark ferruginous orange with a darker band along posterior margin of terga ( Figure 15 ).

Queen diagnosis. Queens of this species are diagnosed by the following combination of features: (1) castespecific morphology of the mesosoma related to wing-bearing and presence of ocelli on head, (2) striae extend over anterior two-thirds or more of medial portion of first gastral tergum, posterolateral margins smooth and shining, (3) transverse rugae cover posterior surface of petiolar node and dorsum of postpetiole, (4) longitudinal rugae on cephalic dorsum posterior to eyes strongly irregular, often with short lateral branches, interrugae strongly granulate, dull, with a beaded appearance, (5) in posterodorsal view, rugae along posterior margin of head and in profile, rugae posterior to eyes strongly irregular, with numerous short lateral branches, (6) in profile, rugae on pronotal sides rugoreticulate, (7) head, pronotum, mesoscutum, mesoscutellum, concolorous reddish-orange to reddish-brown, (8) part to most of anepisternum and/or katepisternum blackish to black, and (9) in profile, hairs on dorsum of mesoscutum and mesoscutellum rarely> 0.5–0.6× MOD ( Figure 16 ).

Measurements —(n = 6). HL 1.59–1.68; HW 1.64–1.74; MOD 0.33–0.38; OMD 0.34–0.44; SL 1.15–1.28; PNW 1.32–1.42; HFL 1.48–1.77; ML 2.24–2.51; PW 0.49–0.54; PPW 0.71–0.82. Indices: SI 67.25–74.85; CI 99.40–104.82; OI 19.54–23.17; HFI 90.24–104.22.

Description. With caste-specific morphology of the mesosoma related to wing-bearing and presence of small ocelli on head. In full-face view, head subquadrate to quadrate (CI = 99.40–104.82), broadest just posterior to eyes, posterior margin flat. Longitudinal rugae on cephalic dorsum prominent, wavy to irregular, rugae posterior to eyes strongly irregular, often with short lateral branches; in posterodorsal view, rugae along posterior margin of head and in profile, rugae posterior to eyes strongly irregular, with numerous short lateral branches. In full-face view, medial rugae continuing to posterior margin, interrugae strongly granulate-punctate, dull, with a beaded appearance; posterior corners irregularly rugose, interrugae weakly to strongly granulate, weakly shining to dull. Mandibles with five to six teeth, dorsal surface rugose. Psammophore moderately well developed.

All mesosomal surfaces except pronotal sides with regular to wavy, subparallel rugae, rugae irregular to rugoreticulate on pronotal sides, interrugae weakly to moderately granulate-punctate, weakly shining; superior propodeal spines long, length about 0.4–0.5× the distance between their bases, acuminate; inferior propodeal spines moderately well developed, wider than tall, apex subangulate to angulate. Peduncle of petiolar node long, anteroventral surface with a weakly to moderately well developed, broadly rounded process that narrows posterad and continues to posterior margin of petiolar node. In profile, petiolar node asymmetrical with anterior surface shorter than posterior surface, apex subangulate to angulate. Posterior surface of petiolar node with wavy, transverse rugae. In dorsal view, postpetiole slightly wider than long; wavy to irregular, transverse 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 weakly granulate-punctate, weakly shining to smooth and shining. Striae extend over anterior two-thirds or more of medial portion of first gastral tergum, posterolateral margins smooth and shining. Most body surfaces with moderately abundant suberect to erect, medium-length, whitish to cream-colored setae. In profile, hairs on dorsum of mesoscutum and mesoscutellum rarely> 0.5–0.6× MOD. Head and mesosoma mostly concolorous reddish-orange to reddish-brown, part to most of anepisternum and/or katepisternum blackish to black; gaster lighter ferruginous orange with a darker transverse band along posterior margin of terga ( Figure 16 ).

Male diagnosis. Males of this species are diagnosed by the following combination of features: (1) first gastral tergum lacking striae, (2) bicolored: head and mesosoma black, gaster ferruginous orange, (3) erect hairs lacking on first gastral tergum, (4) anterior portion to all of anepisternum and katepisternum smooth and shining, (5) posterior surface of petiolar node mostly smooth and shining, (6) dorsum of postpetiole with faint regular, transverse or longitudinal rugae, interrugae mostly smooth and shining, and (7) interrugae on mesoscutum and mesoscutellum weakly granulate, weakly shining to smooth and shining. Note that no characters were found to separate males of P. araucania and P. maulensis ( Figure 17 ).

Measurements —(n = 10). HL 1.14–1.32; HW 1.16–1.34; MOD 0.42–0.46; OMD 0.16–0.24; SL 0.34–0.41; HFL 1.46–1.77; ML 2.17–2.36; PW 0.41–0.55; PPW 0.66–0.73. Indices: SI 26.98–33.62; CI 95.35–108.70; OI 34.13–37.40; HFI 111.45–142.24.

Additional material examined. ARGENTINA: Neuquén: Pino Hachado , Jan 17, 2010 ( RGPC) ; Villa Pehuenia , Jan 19, 2010 ( RGPC) ; 2.5 km W Villa Pehuenia , 3780’, 9 Feb, 2011 ( MCZC; RAJC) ; Angostura , Jan 21–22, 1949 ( IFML) ; Aluminé , Jan 19, 1949 ( LACM; USNM) ; Angostura-Aluminé , Jan 21, 1949 ( IFML) ; 1.6 km W entrance to Parque Nacional Lanin , 3250’, Feb 7, 2011 ( RAJC) ; Lago Tromen , 1050 m, Jan 9, 1995 ( MCZC; UCDC) . CHILE: Araucanía: Rt 181 at 54.6 km SE Longquimay, 5080’, Feb 27, 2014 ( MCZC; RAJC) ( Figure 14B ).

Etymology. The specific epithet, araucania , is a noun in apposition and invariant in form that is derived from the name of the homeland of the Mapuche people in Patagonia (south central Chile and adjacent areas of Argentina).

Discussion. Pogonomyrmex araucania is distinguished from all congeners except for P. spinolae by: (1) first gastral tergum lacking striae, weakly to strongly coriarious along base to over anterior one-half or more of segment or with faint, barely visible, unincised striae on anterior one-third to one-half of segment, (2) superior propodeal spines long, length> 0.6× the distance between their bases, (3) transverse rugae on posterior surface of petiolar node and dorsum of postpetiole, and (4) head and mesosoma concolorous to nearly concolorous light to dark ferruginous orange to reddish-brown. Length of hairs on the dorsum of the mesosoma appears to be the only character that reliably separates P. araucania and P. spinolae . In P. araucania these hairs are shorter with most hairs <0.6–0.7× MOD; these hairs are longer in P. spinolae , with most approaching to exceeding MOD.

Biology. Pogonomyrmex araucania workers are solitary foragers. Nests are placed in open, exposed sites, and the nest entrance ranges from a hole in the ground to a tumulus up to 15 cm in diameter. Sexuals have been collected from 9–27 February and a dealate queen was collected on 27 February, indicating that mating flights occur during the austral summer. Partial nest excavations indicate that colonies probably contain up to 1000 workers. Pogonomyrmex araucania inhabits elevations from 985–1540 m. This species occurs in the Valdivian temperate forests ecoregion, as defined by Olson et al. (2001) ( Figure 14B ).

Figures

FIGURE 14. Geographic distribution of: (A) Pogonomyrmex apterogenos, (B) P. araucania, and (C) P. atacama. The large black circle in each panel denotes the type locality.

FIGURE 15. Photographs of Pogonomyrmex araucania holotype worker: (A) frontal view of head, (B) lateral view of body, and (C) dorsal view of body (CASENT0914128). Photographs by Michele Esposito from www.AntWeb.org.

FIGURE 16. Photographs of Pogonomyrmex araucania paratype alate queen: (A) frontal view of head, (B) lateral view of body, and (C) dorsal view of body (CASENT0914129). Photographs by Michele Esposito from www.AntWeb.org.

FIGURE 17. Photographs of Pogonomyrmex araucania male: (A) frontal view of head, (B) lateral view of body, and (C) dorsal view of body (CASENT0914355). Photographs by Michele Esposito from www.AntWeb.org.