Pheidole similis, Salata & Fisher, 2020

Salata, Sebastian & Fisher, Brian L., 2020, The ant genus Pheidole Westwood, 1839 (Hymenoptera: Formicidae) in Madagascar-taxonomic revision of the bessonii species-group, Zootaxa 4843 (1), pp. 1-64 : 49-51

Pheidole similis sp. nov.

Figs 22 A–F, 27N, 28N

HOLOTYPE: 1s., Madagascar, Antsiranana, Nosy Be, Réserve Naturelle Intégrale de Lokobe , 6.3 km 112° ESE Hellville, -13.41933 48.33117, 30 m, 19-Mar-2001, rainforest, ex rotten log, Fisher et al. leg. BLF03447, CASENT0427852 ( CASC) . PARATYPES: 2w., the same data as holotype, CASENT0427853, CASENT0427854 ( CASC, MHNG) .

Other material. Madagascar. Antsiranana: 3w., Nosy Be, Réserve Naturelle Intégrale de Lokobe , 6.3 km 112° ESE Hellville, -13.41933 48.33117, 30 m, Fisher et al. leg. ( CASC) ; 7w., 1s., Nosy Be, Réserve Naturelle Intégrale de Lokobe , 6.3 km 112° ESE Hellville, -13.41933 48.33117, 30 m, Fisher et al. leg. ( CASC) .

Geographic range. Madagascar, Antsiranana, Nosy Be.

Diagnosis. Major workers. Head in full-face view sub-rectangular, not widening posteriorly, with lateral margins relatively straight; side of head with moderately sparse, short, subdecumbent to suberect pilosity; medial frons with moderately sparse and thick costulae; interspaces between costulae smooth; frons laterally with thick rugocostulae; interspaces between rugocostulae rugulate; occipital lobes with thick rugae; interspaces between rugae smooth; scape, when laid back, exceeding the midlength of head by two-fifths of its length; inner hypostomal tooth distinct, small, bulge-like, with top arching posteroventrally; outer hypostomal tooth lobe-like, high, and wide, with top directed posteriorly; median tooth absent; promesonotum short, angular, and moderately low; posterior mesonotum moderately steep; mesonotal process distinct and tubercle-like; mesosoma microreticulate; promesonotal dorsum with sculpture reduced; gaster shagreened; body orange. Minor workers. Occiput elongated forming short and moderately narrow neck; nuchal collar distinct; head sculpture smooth; scape, when laid back, exceeding the posterior head margin by two-fifths of its length; promesonotum low, long, and arched; promesonotal groove present; metanotal groove distinct; propodeal spines moderate with narrow base; promesonotum smooth; katepisternum and propodeum with sparse puncta; body yellow.

Description. Major workers. Measurements (n=2): HL: 1.55, 1.58; HW: 1.38, 1.47; SL: 1.18, 1.14; EL: 0.21, 0.21; WL: 1.46, 1.44; PSL: 0.3, 0.31; MTL: 1.17, 1.17; PNW: 0.56, 0.58; PTW: 0.21, 0.21; PPW: 0.43, 0.5; CI: 112.2, 107.7; SI: 85.5, 77.7; PSLI: 19.2, 19.3; PPI: 48.1, 41.8; PNI: 40.3, 39.7; MTI: 84.8, 79.9.

Head. In full-face view sub-rectangular, not widening posteriorly, with lateral sides relatively straight ( Fig. 22B ). In lateral view sub-oval, not depressed posteriorly; ventral and dorsal margins convex; inner hypostomal tooth not visible. Side of head with moderately sparse, short, subdecumbent to suberect pilosity; head dorsum with relatively dense, long, decumbent to erect pilosity. Medial frons with moderately sparse and thick costulae; interspaces between costulae smooth. Frons laterally with thick rugocostulae; interspaces between rugocostulae rugulate. Occipital lobes with thick rugae; interspaces between rugae smooth. Gena with dense and thick costulae; interspaces between costulae smooth. Sides posterolateral from eyes with dense but very thin network of rugoreticulae; sculpture slightly weakening posteriorly. Center of clypeus shiny and smooth, lateral sides with distinct rugulae; median notch present, moderately wide and shallow; median longitudinal carina absent; lateral longitudinal carinae absent. Scape, when laid back, exceeding the midlength of head by two-fifths of its length; pilosity subdecumbent to erect ( Fig. 22B, D ). Inner hypostomal tooth distinct, small, bulge-like, with top arching posteroventrally; outer hypostomal tooth lobe-like, high, and wide, with top directed posteriorly; median tooth absent ( Fig. 27N ). Mesosoma. In lateral view, promesonotum short, angular, and moderately low; posterior mesonotum moderately steep; mesonotal process distinct and tubercle-like; promesonotal groove absent; metanotal groove present; propodeal spines moderately long, with narrow base and acute top; humeral tubercle weakly produced ( Fig. 22D ). Surface shiny and microreticulate; promesonotal dorsum with sculpture reduced. Pilosity moderately dense, moderately long, and erect ( Fig. 22D, F ). Petiole. In rear view node dorsoventrally slightly convex ( Fig. 22D, F ). Gaster. Shiny and shagreened; pilosity moderately sparse, long, and erect ( Fig. 22D, F ). Color. Orange, legs yellow, gaster darker than mesosoma ( Fig. 22D, F ).

Description. Minor workers. Measurements (n=10): HL: 0.7–0.89 (0.81); HW: 0.46–0.57 (0.52); SL: 1.01– 1.28 (1.18); EL: 0.13–0.17 (0.14); WL: 0.89–1.24 (1.06); PSL: 0.12–0.17 (0.15); MTL: 0.79–1.2 (0.99); PNW: 0.32–0.44 (0.37); PTW: 0.07–0.12 (0.09); PPW: 0.12–0.21 (0.15); CI: 152.4–161.2 (156.0); SI: 220.8–237.2 (228.0); PSLI: 15.1–20.7 (18.2); PPI: 52.4–70.6 (61.6); PNI: 68.2–77.4 (71.5); MTI: 161.5–211.0 (190.5).

Head. In full-face view oval, posterior region elongated forming short and moderately narrow neck; nuchal collar distinct ( Fig. 22A ). Pilosity relatively sparse, long, and subdecumbent to erect. Sculpture shiny and mostly smooth; antennal sockets with few indistinct rugulae that are curved posterolaterally; interspaces between rugulae smooth. Clypeus with median longitudinal carina absent; two lateral longitudinal carinae absent. Scape, when laid back, exceeding the posterior head margin by two-fifths of its length; pilosity dense, subdecumbent to erect ( Fig. 22A, C ). Mesosoma. In lateral view, promesonotum low, long, and arched; promesonotal groove present; metanotal groove distinct; propodeal spines moderate and triangular, with narrow base ( Fig. 22C ). Promesonotum smooth; katepisternum and propodeum sparsely punctate. Pilosity very sparse, long, and erect ( Fig. 22C, E ). Gaster. With sparse and erect pilosity ( Fig. 22C, E ). Color. Yellow, gaster and head darker than mesosoma ( Fig. 22C, E ).

Biology. The species was collected at 30 m elevation, in rainforest. Nests were located in rotten logs. Workers were collected from sifted litter.

Comments. Among species known from Nosy Be islet, Pheidole similis is the only member of the bessonii group with both minor and major workers yellow to orange. It is most similar to two species known from the eastern parts of Antsiranana and the northernmost part of Toamasina: P. clara and P. mantadioflava . Its major workers differ from these two taxa in frons laterally with thick rugocostulae, and with rugulate interspaces between rugulae. Majors of P. clara and P. mantadioflava have frons laterally entirely punctate or rugulate with punctate interspaces between rugulae. Minor workers can be easily separated based on smooth promesonotum. Pheidole similis is morphologically most similar to P. ragnax , described by Fischer & Fisher from Mayotte island. Minors of P. similis can be separated based on longer and more narrow neck, and presence of sparse but distinct puncta on katepisternum and propodeum. Majors differ in more rugulate lateral frons, sparser setae on sides of head, more distinct and dense mesosomal sculpture, and shagreened gaster.

Etymology. Latin for similar, in reference to the morphological similarity of P. similis to P. ragnax .

Figures

FIGURE 22. Pheidole similis, full-face view (A), profile (C), and dorsal view (E) of paratype minor worker (CASENT0427853) and full-face view (B), profile (D), and dorsal view (F) of holotype major worker (CASENT0427852).

FIGURE 27. Major worker, hypostomal tooth. Pheidole antsahabe (A). Pheidole atsirakambiaty (B). Pheidole bessonii (C). Pheidole clara (D). Pheidole decollata (E). Pheidole flammea (F). Pheidole flavodepressa (G). Pheidole grallatrix (H). Pheidole madecassa (I). Pheidole mantadioflava (J). Pheidole maro (K). Pheidole oswaldi (L). Pheidole ovalinoda (M). Pheidole similis (N). Pheidole tenebrovulgaris (O). Pheidole uranus (P). Pheidole voreios (Q). Pheidole zirafy (R).