Pogonomyrmex weiseri REVIVED STATUS

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 : 216-223

Pogonomyrmex weiseri REVIVED STATUS

( Figures 109–111 )

Distribution—112A

Pogonomyrmex weiseri Santschi 1922b: 348 (worker, queen, male). Syntypes examined: 1 worker [MCZC], 1 worker [MHNG], 1 worker [MZSP], 3 workers, 2 alate queens [MACN] (1 worker NHMB, not examined). ARGENTINA, Catamarca: Valle San María, Ampajango, #1362 (Ing. Weiser leg.). See also Gallardo, 1932: 145, figs. 30, 31. MCZC worker here designated LECTOTYPE [CASENT0217261].

Pogonomyrmex rastratus Mayr : Kusnezov, 1951: 252, incorrect synonymy.

Worker diagnosis. Workers of this species are uniquely characterized by the following combination of features: (1) striae extend over anterior one-half or more of first gastral tergum, posterior margin with striae or moderately to strongly coriarious; posterolateral margins roughened or weakly to strongly coriarious, weakly shining to dull, (2) head and gaster ferruginous orange; mesosoma black, dorsum of promesonotum often with an orangish infusion, (3) superior propodeal spines long, length> 0.6× the distance between their bases, (4) longitudinal rugae on dorsum of mesonotum regular to moderately irregular, subparallel-parallel, lateral branches usually absent and adjacent rugae rarely contacting one another, (5) mandibles with six teeth, (6) promesonotal suture usually present, and (7) occurs from La Rioja to Salta ( Figure 109 ).

Measurements — lectotype (n = 13). HL 1.91 (1.62–1.98); HW 2.01 (1.63–2.05); MOD 0.44 (0.36–0.44); OMD 0.51 (0.45–0.59); SL 1.30 (1.17–1.49); PNW 1.25 (1.04–1.31); HFL 1.82 (1.46–1.90); ML 2.24 (1.86–2.45); PW 0.51 (0.40–0.56); PPW 0.73 (0.59–0.76). Indices: SI 64.68 (62.57–74.58); CI 105.24 (100.00–107.37); OI 21.89 (19.51–23.93); HFI 90.55 (84.88–96.22).

Redescription. Head quadrate to wider than long (CI = 100.00–107.37); posterior margin flat in full-face view. Longitudinal rugae on cephalic dorsum prominent; in full-face view, medial rugae diverging toward posterior corners of head. Interrugae on cephalic dorsum moderately granulate, dull, with a weakly beaded appearance. Rugae on posterior corners absent to weak, interrugae smooth to moderately granulate, weakly shining to shining. Anterior margin of clypeus strongly concave, dorsum with numerous subparallel-parallel, longitudinal rugae. Numerous long, curved, bristle-like, cream colored to light yellowish macrochaetae project from anterior margin of clypeus and basolateral margins of mandibles. Mandibles with six teeth; mandibular dorsum coarsely rugose. MOD ranging from 0.21–0.24× HL. In profile, eyes situated slightly anterior to middle of head, OMD = 1.1–1.4× MOD. In full-face view, eyes not protruding to protruding slightly beyond lateral margins of head. Antennal scapes (SI = 62.57–74.58) failing to reach posterior corners of head by less than length of basal funicular segment. Antennal scapes with weak longitudinal striae, weakly shining to shining; basal flange well developed with carinate margin. Psammophore well developed.

Mesosomal profile weakly to moderately convex; all mesosomal surfaces with prominent subparallel-parallel, regular to moderately irregular rugae. In dorsal view, humeral shoulders of pronotum enlarged, dorsolateral margins weakly to strongly angulate. Dorsum of mesonotum with regular to moderately irregular, subparallel-parallel, longitudinal rugae, lateral branches usually absent and adjacent rugae rarely contacting one another; rugae diverge anterad toward humeral shoulders of pronotum. Irregular rugae on pronotal sides traverse ventrally or posteroventrally; rugae on mesopleura angle posterodorsally. Promesonotal suture usually present. Superior propodeal spines long, length usually> 0.6× the distance between their bases, tips blunt, spines connected by well defined keel; irregular transverse rugae on dorsum of propodeum traverse ventrally or anteroventrally on sides. Inferior propodeal spines slightly wider than high, apex weakly blunt to acuminate. Propodeal spiracles narrowly ovate facing posterad. Interrugae on mesosoma densely granulate-punctate, weakly dull to weakly shining. Legs weakly shining to shining.

Peduncle of petiole about as long as petiolar node, anteroventral margin often with a broad, rounded expansion, but lacking triangular process. In profile, posterior surface of petiolar node weakly convex; petiolar node asymmetrical with anterior surface shorter than posterior surface, apex angulate to moderately rounded. In dorsal view, petiolar node longer than wide, widest near rounded anterior margin, narrowing posterad. Sides and posterior surface of petiolar node with weakly to moderately irregular transverse rugae, occasionally traversing longitudinally or obliquely near anterior margin. 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. Rugae on dorsum of postpetiole transverse or more often curving anterad; 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. First gastral tergum with striae that extend over anterior one-half or more of segment, posterolateral margins roughened or weakly to strongly coriarious, weakly shining to dull.

Erect white pilosity moderately abundant on head, mostly similar in length with up to several longer hairs, longest not exceeding 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 erect, moderately dense, white setae that are similar in length. Head and gaster ferruginous orange; mesosoma black, dorsum of promesonotum often with an orangish infusion; peduncle of petiole, petiolar node, anterior portion of postpetiole dark orangish-black, ventral and posterior portion of postpetiole weakly to moderately ferruginous orange; frontal lobes, mandibles, antennae, legs dark orange-black to nearly black ( Figure 109 ).

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 on first gastral tergum usually extend to posterior margin, posterolateral margins with striae or moderately to strongly coriarious, weakly shining, (3) head and gaster ferruginous orange; pronotal sides, anepisternum concolorous blackish to black, (4) interrugae on cephalic dorsum strongly granulate, dull, (5) queens large (HW = 1.95–2.21 mm; PNW = 1.42–1.56 mm; ML = 2.55–2.91 mm), (6) superior propodeal spines moderately long, length usually> 0.5× the distance between their bases, (7) longest hairs on first gastral sternite approximately 0.2–0.4× MOD, and (8) occurs from La Rioja to Salta ( Figure 110 ).

Measurements —(n = 8 + 2 paralectotypes). HL 1.77–2.11; HW 1.95–2.21; MOD 0.41–0.48; OMD 0.45–0.54; SL 1.16–1.46; PNW 1.42–1.56; HFL 1.79–1.97; ML 2.55–2.91; PW 0.51–0.61; PPW 0.78–0.86. Indices: SI 55.77– 70.53; CI 99.49–117.51; OI 20.09–21.72; HFI 86.96–98.46.

Male diagnosis. Males of this species are diagnosed by the following combination of features: (1) first gastral tergum mostly smooth and shining, lacking striae or striae extend over anterior one-half or more of first gastral tergum, (2) mesoscutum mostly smooth and shining, and (3) notauli present, sometimes weakly impressed ( Figure 111 ).

Measurements —(n = 12). HL 1.15–1.66; HW 1.25–1.55; MOD 0.48–0.54; OMD 0.14–0.26; SL 0.34–0.51; HFL 1.38–1.75; ML 2.15–2.96; PW 0.49–0.66; PPW 0.68–0.89. Indices: SI 26.36–35.88; CI 92.14–117.39; OI 34.84–38.40; HFI 102.99–132.56.

Additional material examined. ARGENTINA: Catamarca: Rt 40 at 13.3 km S Punta Balasto , 7360’, Feb 2, 2010 ( IFML; RAJC) . La Rioja: Rt 11 at 4.3 km SE Angulos , 6100’, Jan 4, 2006 ( IFML; MCZC; RAJC) . Salta: Rt 40 at 32.3 km N Cafayate , 5460’, Jan 11, 2006 ( MCZC; RAJC) ; 20.3 km W Angastaco , 8280’, Jan 12, 2006 ( MCZC; RAJC) ; Rt 40 at 41.6 km NW Angastaco , 6670’, Jan 12, 2006 ( RAJC) ; Rt 33 at 6.2 km SE Payogasta , 8620’, Jan 12, 2006 ( RAJC) ; Rt 33 at 14.6 km SE Payogasta , 9340’, Jan 12, 2006 ( CASC; IFML; MCZC; RAJC; UCDC) ; 6.2 km SE Jct Rts 33 & 42, 9610’, Jan 20, 2010 ( RAJC) ; San Pedro de Yacochuya , 1875 m, Feb 2, 2012 ( RAJC) ; Rt 40 at 11.7 km S Seclantas turnoff, 7250’, Mar 26, 2015 ( RAJC) ; Rt 40 at 42.0 km N Jct Rt 33, 10,070’, Mar 27, 2015 ( RAJC) ; Rt 40 at 34.9 km N Jct Rt 33, 9370’, Mar 27, 2015 ( RAJC) . Tucumán: Rt 307 at 6.8 km NW Amaiche , 6080’, Jan 27, 2010 ( RAJC) ; 7 km SW Amaiche de Valle , 2100 m, Feb 3, 1995 ( MCZ; UCDC) ; Rt 40 at 8.4 km NW Amaiche del Valle , 6050’, Mar 24, 2015 ( RAJC) ; Rt 307 at 8.0 km NW El Infiernillo, 9100’, Jan 18, 2010 ( RAJC) ( Figure 112A ).

Etymology. The specific epithet, weiseri (Latinization of Weiser), was derived from Weiser, who collected the syntype series of workers.

Discussion. Pogonomyrmex weiseri is separated from most congeners by: (1) striae extend over anterior onehalf or more of first gastral tergum, posterior margin with striae or moderately to strongly coriarious, and posterolateral margins moderately to strongly coriarious, weakly shining to dull. These characters separate P. weiseri from all but three congeners: P. carbonarius , P. mapuche , and P. propinqua . Pogonomyrmex weiseri is most similar to P. propinqua , from which it is separated by: (1) longitudinal rugae on dorsum of promesonotum more regular, usually do not contact one another, and lack short lateral branches, and (2) interrugae on cephalic dorsum weakly to moderately granulate-punctate, weakly shining, with a weakly beaded appearance. In P. propinqua , (1) longitudinal rugae on dorsum of promesonotum irregular to rugoreticulate, with short lateral branches that usually contact one another, and (2) interrugae on cephalic dorsum strongly granulate-punctate, dull, with a beaded appearance. These two species are also separated geographically as P. weiseri occurs in more northern provinces (La Rioja to Salta) than P. propinqua (San Luis and Mendoza).

Pogonomyrmex weiseri is separated from P. mapuche by: (1) for at least some workers in a series, superior propodeal spines long, length> 0.4–0.6× the distance between their bases, (2) head and/or gaster ferruginous orange or reddish-orange, and (3) mandibles with six teeth. In P. mapuche : (1) superior propodeal spines consist of tubercles or denticles, rarely short acuminate teeth, (2) head dark red to reddish-black; gaster reddish-blackish to black, and (3) mandibles with seven teeth for some to most workers in a series.

Pogonomyrmex weiseri is separated from P. carbonarius by: (1) head and gaster ferruginous orange, (2) mandibles with six teeth, and (3) longitudinal rugae on dorsum of promesonotum more regular, usually not contacting one another, and lack short lateral branches. In P. carbonarius : (1) head and/or gaster usually reddish-orange to black, (2) mandibles with six to seven teeth, and (3) longitudinal rugae on dorsum of promesonotum irregular to rugoreticulate with short lateral branches that usually contact one another. These two species are also separated geographically as P. weiseri occurs in more northern provinces (La Rioja to Salta) than P. carbonarius (Mendoza to Chubut). Based on the above morphological differences and its distinct geographic range, I revive P. weiseri from synonymy to rank as a valid species.

Pogonomyrmex weiseri was described by Santschi (1922b), and Kusnezov (1951) synonymized P. weiseri under P. rastratus explaining that Santschi mistakenly identified his specimens using the incorrect description of P. rastratus given by Mayr (1887). A complete account is given in the discussion under P. carbonarius .

In regard to the type locality, the MHNG and MZSP specimens were labeled Catamarca, while the MCZC specimen was labeled Catamarca, Ampango, Valle San María, and the MACN specimens were labeled as Ampajango, Catamarca. Santschi (1922b) listed the type locality as Ampajanga, Valle Santa María , but the type locality is Ampajango , Valle Santa María ; both Ampajanga and Ampango are misspellings .

Biology. Pogonomyrmex weiseri workers are solitary foragers. Nests of P. weiseri most commonly are placed in open, exposed sites. The nest entrance ranges from a hole in the ground to a tumulus up to 15 cm in diameter. Nests are most easily located by baiting workers with cookie crumbs, then following them back to the nest. Partial nest excavations indicated that colonies contain approximately 600–1000 workers. Sexuals have been collected on January 12, and a mating flight was observed at 15:30 h on that same day, indicating that mating flights occur during the austral summer. The mating aggregation consisted of approximately 200–300 sexuals near the top of a Trichocereus sp. (Cactaceae) .

Pogonomyrmex weiseri inhabits sites at elevations from 1655–3050 m, but seems to be more common at higher elevations. This species is largely restricted to the High Monte ecoregion with one record from the Central Andean puna ecoregion, as defined by Olson et al. (2001) ( Figure 112A ).

Figures

FIGURE 109. Photographs of Pogonomyrmex weiseri worker: (A) frontal view of head, (B) lateral view of body, and (C) dorsal view of body (CASENT0172679). Photographs by April Nobile from www.AntWeb.org.

FIGURE 110. Photographs of Pogonomyrmex weiseri alate queen: (A) frontal view of head, (B) lateral view of body, and (C) dorsal view of body (CASENT0922459). Photographs by Michele Esposito from www.AntWeb.org.

FIGURE 111. Photographs of Pogonomyrmex weiseri male: (A) frontal view of head, (B) lateral view of body, and (C) dorsal view of body (CASENT0172680). Photographs by April Nobile from www.AntWeb.org.

FIGURE 112. Geographic distribution of: (A) Pogonomyrmex weiseri, and (B) P. wilsoni. The large black circle in each panel denotes the type locality.