Pogonomyrmex intermedia (Menozzi, 1935) 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 : 89-96

Pogonomyrmex intermedia NEW STATUS

( Figures 40–42 )

Distribution—43A

Pogonomyrmex (Ephebomyrmex) bispinosus var. intermedia Menozzi, 1935: 320 (worker). Syntypes not examined. CHILE, Bíobío: Volcán de Chillan , 1700 m, #204 (Prof. W. Goetsch leg.). GGC worker here designated LECTOTYPE [ANT- WEB1008896].

Pogonomyrmex (Pogonomyrmex) bispinosus var. intermedius Menozzi : Kempf, 1972: 207, first combination in Pogonomyrmex (Pogonomyrmex) . Snelling & Hunt, 1975: 75, incorrect synonymy under vermiculatus .

Worker diagnosis. Workers of this species are uniquely characterized by the following combination of features: (1) first gastral tergum lacking striae, (2) head and gaster ferruginous orange to reddish-orange, pronotum orangish to reddish, mesonotum and propodeum blackish to black, often with an orangish to reddish infusion on dorsum of mesonotum, (3) legs and antennal scapes usually orangish-brown, occasionally brownish to blackish, (4) clypeus orangish to orangish-red, concolorous with adjacent cephalic dorsum, (5) promesonotal suture usually present, pronotum usually lighter than adjoining mesonotum, (6) transverse rugae on posterior surface of petiolar node and dorsum of postpetiole, and (7) superior propodeal spines long, length> 0.6–0.8× the distance between their bases ( Figure 40 ).

Measurements —(n = 12). HL 1.42–1.80; HW 1.43–1.84; MOD 0.33–0.39; OMD 0.30–0.44; SL 1.11–1.43; PNW 0.98–1.21; HFL 1.53–1.96; ML 1.73–2.17; PW0.38–0.49; PPW 0.54–0.68. Indices: SI 75.54–80.77; CI 97.50–106.98; OI 19.30–23.78; HFI 96.49–109.79.

Redescription. Head subquadrate to quadrate (CI = 97.50–106.98); posterior margin flat to weakly convex in full-face view. Longitudinal rugae on cephalic dorsum prominent, wavy to irregular; in full-face view, medial rugae diverging toward posterior corners of head. Interrugae on cephalic dorsum strongly granulate, dull, usually with a beaded appearance; posterior corners rugose, interrugae moderately granulate, weakly shining to smooth and strongly shining. Anterior margin of clypeus moderately concave, dorsum with several subparallel, longitudinal rugae. Numerous long, curved, bristle-like, cream colored to light yellowish macrochaetae project from anterior margin of clypeus and basolateral margin of mandibles. Mandibles with six teeth; mandibular dorsum coarsely rugose. MOD ranging from 0.19–0.24× HL. In profile, eyes situated slightly anterior to middle of head, OMD = 0.89–1.25× MOD. In full-face view, eyes protruding slightly beyond lateral margins of head. Antennal scapes (SI = 75.54–80.77) reaching posterior margins of head or failing to do so by less than width of basal funicular segment. Antennal scapes with longitudinal striae, interstriae weakly to moderately granulate, weakly shining; basal flange well developed with carinate margin. Psammophore well developed.

Mesosomal profile weakly to moderately convex. In dorsal view, humeral shoulders of pronotum enlarged, shoulders weakly to strongly angulate. All mesosomal surfaces with prominent rugae. Dorsum and sides of pronotum rugoreticulate, wavy to strongly irregular rugae on mesopleura angle posterodorsally. Dorsum of promesonotum with weakly to strongly irregular longitudinal rugae, sometimes weakly rugoreticulate. Promesonotal suture usually present. Superior propodeal spines long, length> 0.6–0.8× distance between their bases, connected by well defined keel; irregular transverse rugae to rugoreticulate on dorsum of propodeum. Inferior propodeal spines wider than high, apex weakly rounded to subacuminate. Propodeal spiracles narrowly ovate facing posterad. Interrugae on mesosoma moderately to densely granulate, dull to weakly shining. Legs moderately coriarious, weakly shining.

Peduncle of petiole about as long as petiolar node, ventral surface often with a broadly rounded process. In profile, dorsum of petiolar node weakly convex; node asymmetrical with anterior surface notably longer than posterior surface, apex angulate to weakly rounded. In dorsal view, petiolar node longer than wide, widest near spatulate anterior margin, gradually narrowing posterad. Sides and posterior surface of petiolar node with wavy to irregular transverse to arcuate rugae. Dorsum of postpetiole convex in profile; in dorsal view, widest near posterior margin, narrowing to anterior margin, maximum width and length about equal. Wavy, transverse rugae on dorsum of postpetiole finer, denser than those on posterior surface of petiolar node; interrugae on both surfaces moderately to strongly granulate, dull to weakly shining. First gastral tergum smooth and shining to moderately coriarious, weakly shining, sculpturing near base sometimes appearing in a longitudinal manner giving the appearance of faint striae.

Erect, mostly short to medium length, yellowish pilosity moderately abundant on head. Moderately abundant suberect to decumbent pilosity on scape; abundant decumbent hairs on funicular segments. Legs with moderately abundant suberect to semidecumbent yellowish setae. Mesosoma, petiolar node, postpetiole, and gastral terga with moderately dense, erect, yellowish setae that are similar in length; longest hairs about 0.6–0.7× MOD. Head and gaster ferruginous orange to reddish-orange; pronotum orangish to reddish, lighter than adjoining mesonotum; mesonotum and propodeum blackish to black, often with an orangish to reddish infusion on dorsum of mesonotum; antennae, legs, petiolar node dark orangish-brown, occasionally brownish to blackish; postpetiole blackish-orange ( Figure 40 ).

Queen diagnosis. Queens of this species are diagnosed by the following combination of features: (1) caste-specific morphology of the mesosoma related to wing-bearing and presence of ocelli on head, (2) first gastral tergum lacking striae, smooth and strongly shining, (3) posterior surface of petiolar node and dorsum of postpetiole covered with transverse rugae, (4) superior propodeal spines moderately long, length> 0.3–0.5× the distance between their bases, (5) mesopleura, propodeum, petiolar node blackish to black; mesoscutum and mesoscutellum orangishbrown to reddish-brown, and (6) longitudinal rugae on cephalic dorsum posterior to eyes strongly irregular, often with short lateral branches, interrugae strongly granulate, with a beaded appearance, dull ( Figure 41 ).

Measurements —(n = 9). HL 1.45–1.73; HW 1.51–1.77; MOD 0.30–0.38; OMD 0.34–0.40; SL 1.11–1.32; PNW 1.17–1.34; HFL 1.54–1.81; ML 2.05–2.48; PW 0.38–0.46; PPW 0.60–0.70. Indices: SI 71.19–77.42; CI 97.42–106.90; OI 19.23–23.23; HFI 97.47–108.61.

Description. With caste-specific morphology of the mesosoma related to wing-bearing and presence of ocelli on head. In full-face view, head subquadrate to slightly wider than long (CI = 97.42–106.90), widest 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, interrugae strongly granulate, dull, with a beaded appearance; in posterodorsal view, medioposterior margin of head with a more or less triangular area that is rugoreticulatevermiculate; posterior margin rugose to rugoreticulate, interrugae weakly to strongly granulate-punctate, weakly shining to dull. Mandibles with six teeth, rarely with an additional denticle between basal and subbasal teeth, dorsal surface coarsely rugose. Psammophore well developed.

All mesosomal surfaces with subparallel, regular, wavy, or irregular rugae, except for irregular to rugoreticulate-vermiculate on pronotal sides; interrugae on mesoscutum and mesoscutellum weakly to moderately granulate, weakly shining, those on propodeum moderately granulate-punctate, weakly shining. Propodeum with moderately long superior spines, length approximately 0.3–0.5× the distance between their bases; inferior propodeal spines wider than tall, apex weakly to broadly rounded. Peduncle of petiolar node long, anteroventral margin with a moderately well developed, broadly rounded process that narrows and continues posterad more or less parallel to dorsal surface of peduncle. In profile, petiolar node asymmetrical with anterior surface notably shorter than posterior surface, apex subangulate to angulate. Posterior surface of petiolar node with transverse rugae; 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 to moderately granulate-punctate, weakly shining. First gastral tergum smooth and strongly shining. Most body surfaces with moderately abundant suberect to erect, medium-length, whitish setae, most hairs on head> 0.3–0.4× MOD. Bicolored: head, mesoscutum, mesoscutellum, gaster dark orangish-brown to reddish-brown; pronotum, mesopleura, propodeum, petiolar node, postpetiole, antennae, legs blackish to black ( Figure 41 ).

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 with irregular rugae to rugoreticulate, interrugae weakly shining, (6) dorsum of postpetiole with irregular longitudinal rugae, interrugae moderately to strongly granulate, dull to weakly shining, and (7) interrugae on mesoscutum and mesoscutellum strongly granulate, dull ( Figure 42 ).

Measurements —(n = 3). HL 1.27–1.31; HW 1.19–1.28; MOD 0.42–0.46; OMD 0.14–0.20; SL 0.41–0.45; HFL 1.60–1.76; ML 2.24–2.50; PW 0.46–0.53; PPW 0.69–0.74. Indices: SI 34.38–35.43; CI 93.70–100.00; OI 35.29–35.94; HFI 129.69–138.58.

Additional material examined. CHILE: Bíobío: Las Trancas Road near Termas de Chillan , 1350 m, Feb 15, 1967 ( CASC; LACM; MNHNC; RAJC) (labels list incorrect latitude-longitude); Las Trancas at Piramahuida Hotel, 4070’, Mar 2, 2014 ( IFML; LACM; MCZC; MNNC; RAJC; UCDC; USNM) ( Figure 43A ) .

Etymology. Menozzi described P. intermedia by comparing it to two other Chilean taxa, P. bispinosus and P. bispinosus var. semistriatus , indicating that the sculpturing of P. intermedia was similar to that of P. bispinosus var. semistriatus , and much more pronounced than in P. bispinosus , but that the gaster was smooth and shining as in P. bispinosus (whereas the gaster of P. semistriatus was finely striate). Thus, the name intermedia appears to be derived from this species having characters intermediate to those of P. bispinosus and P. bispinosus var. semistriatus .

Discussion. Pogonomyrmex intermedia is not known to co-occur with any congeners. Pogonomyrmex maulensis and P. santschii are the only species that might be confused with P. intermedia , as both are bicolored, with an orangish to reddish head and gaster and blackish to black mesosoma, and both lack striae on the first gastral tergum. All other congeners that lack striae on the first gastral tergum are mostly concolorous ferruginous orange to reddishbrown. Pogonomyrmex intermedia is separated from P. maulensis based on: (1) medial portion of clypeus concolorous to adjoining cephalic dorsum, (2) legs and antennal scapes usually orangish-brown, occasionally brownish to blackish, and (3) mesosoma concolorous ferruginous orange to reddish-brown to reddish-black or posterior portion of mesopleura and propodeum blackish to black. In P. maulensis : (1) for most to all workers in a series, medial portion of clypeus notably darker (usually blackish to black) than adjoining cephalic dorsum, (2) legs and antennal scapes black, and (3) posterior portion of mesopleura and propodeum usually reddish-black, sometimes blackish to black. Pogonomyrmex intermedia is separated from P. santschii based on: (1) pronotum to entire mesosoma ferruginous orange to reddish-brown or reddish-black, whereas in P. santschii : (1) mesosoma black, occasionally with a weak orangish to reddish infusion on pronotum, infusion rarely present on mesonotum.

For reasons that are unclear, Menozzi (1935) described the worker of P. intermedia as being within the subgenus Ephebomyrmex even though he placed it as a subspecies of P. bispinosus . His description compared P. intermedia to P. bispinosus and P. semistriata , indicating it as distinct from both of these forms in that the antennae, thorax, and petiolar node were black, while the head, pronotum, and gaster were dark red ( P. bispinosus and P. semistriatus are mostly concolorous dark ferruginous orange to reddish-brown). He also noted that: (1) sculpturing on P. intermedia was similar to that on P. semistriata and more pronounced than that on the type ( bispinosus ), and (2) that the gaster was smooth and shining as in the type.

I did not examine syntypes of P. intermedia , but the GGC curator (Giovanni Giorgio Bazzocchi) emailed photographs of one syntype and the label (available at http://www.asu.edu/clas/sirgtools/pogonomyrmex/intermedia%20-%20second%20layer%20photo%20map%20template.htm & https://www.antweb.org/specimen. do?code=antweb1008896); this syntype was designated as a lectotype (see above). Workers collected near the base of Volcán de Chillan matched photos of this syntype worker in regard to color and other discernable characters .

The only subsequent taxonomic work on P. bispinosus var. intermedia removed this taxon from synonymy un- der P. bispinosus and placed it as a junior synonym of P. vermiculatus ( Snelling & Hunt, 1975) . In their discussion, Snelling & Hunt (1975) indicated that P. bispinosus was a distinct species and that the several Chilean forms attributable to P. bispinosus (i.e., intermedia , semistriatus, spinolae ) were more closely related to P. vermiculatus , and they then synonymized all of these taxa under P. vermiculatus . Snelling & Hunt (1975) justified these synonymies saying that they could not recognize any nominate form given so many populations of indeterminate status. These authors did not examine syntypes of P. vermiculatus or of any other form that they synonymized under it, and they appear to have examined only one series of the true P. vermiculatus (from Magallanes Province, Chile). Examination of photos of one syntype and of numerous specimens collected from near the type locality demonstrate that P. intermedia is morphologically distinct from all other known forms. Thus, I raise P. intermedia from synonymy to rank as a valid species.

Biology. Nothing is known about the biology of P. intermedia except that workers are solitary foragers. This species appears to be restricted to areas along the western base of the Sierra Nevada of Chile. Much of this area is forested and colonies were located in forest openings and disturbed areas. Sexuals were collected from nests on March 2, suggesting that mating flights occur during the austral summer. One dealate, brachypterous queen was also collected; it is unknown if brachypterous queens are rare or common. Partial nest excavations indicated that colonies contain approximately 500– 800 workers. Pogonomyrmex intermedia appears to be a mid-elevation species that inhabits elevations from 1235–1700 m. This species occurs in the Valdivian temperate forests ecoregion, as defined by Olson et al. (2001) ( Figure 43A ).

Figures

FIGURE 40. Photographs of Pogonomyrmex intermedia worker: (A) frontal view of head, (B) lateral view of body, and (C) dorsal view of body (CASENT0914380). Photographs by Michele Esposito from www.AntWeb.org.

FIGURE 41. Photographs of Pogonomyrmex intermedia alate queen: (A) frontal view of head, (B) lateral view of body, and (C) dorsal view of body (CASENT0914382). Photographs by Michele Esposito from www.AntWeb.org.

FIGURE 42. Photographs of Pogonomyrmex intermedia male: (A) frontal view of head, (B) lateral view of body, and (C) dorsal view of body (CASENT0914384). Photographs by Michele Esposito from www.AntWeb.org.

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.