Pheidole oswaldi Forel, 1891

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 : 44-47

Pheidole oswaldi Forel, 1891

Figs 20 A–F, 27L, 28L

Pheidole oswaldi Forel, 1891: 173 (s.w.q.m.).

LECTOTYPE [designated here]: 1s., Madagascar, Toamasina, 30 miles SW Toamasina, 28.IX.1889, coll. Oswald, CASENT0101640,ANTC3354 ( MHNG) . PARALECTOTYPES: 3w., the same data as lectotype, CASENT0101724, ANTC3355 ( MHNG) ; 1q., Imerina, coll. Sikora, CASENT0101808, ANTC3353 ( MHNG); 1m ., Imerina, coll. Sikora, CASENT0101706, ANTC3356 ( MHNG) .

Other material. Madagascar. Fianarantsoa: 3w., 1s., Parc National de Ranomafana, Vatoharanana River, 4.1 km 231° SW Ranomafana, -21.29 47.43333, 1100 m, Fisher et al. leg. ( CASC) . Toamasina: 2w., 1s., 5.3 km SSE Ambanizana, Andranobe, -15.67133 49.97395, 425 m, Fisher et al. leg. ( CASC) ; 8w., 3q., Ankerana, -18.4061 48.82029, 725 m, Fisher et al. leg. ( CASC) ; 1w., 1s., Ankerana, -18.40062 48.81311, 865 m, Fisher et al. leg. ( CASC) ; 8w., Ankerana, -18.40636 48.80254, 1108 m, Fisher et al. leg. ( CASC) ; 6w., 2s., 1m . , Ankerana , -18.4061 48.82029, 725 m, Fisher et al. leg. ( CASC); 1w., 1s., Ankerana, -18.40672 48.82281, 681 m, Fisher et al. leg. ( CASC) ; 2w., 1s., 1m . , Ankerana , -18.40636 48.80254, 1108 m, Fisher et al. leg. ( CASC); 1w., F.C. Andriantantely , -18.695 48.81333, 530 m, H. J. Ratsirarson leg. ( CASC) ; 6w., F.C. Sandranantitra , -18.04833 49.09167, 450 m, H. J. Ratsirarson leg. ( CASC) ; 2w., Montagne d’Akirindro 7.6 km 341° NNW Ambinanitelo, -15.28833 49.54833, 600 m, Fisher et al. leg. ( CASC) ; 26w., 12s., Montagne d’Anjanaharibe, 18.0 km 21° NNE Ambinanitelo, -15.18833 49.615, 470 m, Fisher et al. leg. ( CASC) ; 5s., Montagne d’Anjanaharibe , 19.5 km 27° NNE Ambinanitelo, -15.17833 49.635, 1100 m, Fisher et al. leg. ( CASC) ; 1s., Nosy Mangabe , 7.43 km S Maroantsetra, -15.4973 49.76223, 3 m, Fisher et al. leg. ( CASC) ; 1w., 1s., Parc National de Zahamena, -17.73359 48.72625, 950 m, Fisher et al. leg. ( CASC) ; 2w., 1s., Parc National de Zahamena, Tetezambatana forest, near junction of Nosivola and Manakambahiny Rivers , -17.74298 48.72936, 860 m, Fisher et al. leg. ( CASC) ; 1w., 1s., Parc National Mananara-Nord, 7.1 km 261° Antanambe, -16.455 49.7875, 225 m, Fisher et al. leg. ( CASC) ; 2w., 2s., Res. Ambodiriana, 4.8 km 306° Manompana, along Manompana river , -16.67233 49.70117, 125 m, Fisher et al. leg. ( CASC) ; 2w., 2s., Reserve Betampona, Camp Rendrirendry 34.1 km 332 ° Toamasina, -17.924 49.19967, 390 m, Fisher et al. leg. ( CASC) ; 2w., 2s., Reserve Betampona, Camp Vohitsivalana , 37.1 km 338 ° Toamasina, -17.88667 49.2025, 520 m, Fisher et al. leg. ( CASC) ; 2w., 1s., 1m . , Réserve Spéciale Ambatovaky, Sandrangato river , -16.81753 49.29498, 360 m, Fisher et al. leg. ( CASC); 2w., 1m., Réserve Spéciale Ambatovaky, Sandrangato river, -16.76912 49.26704, 475 m, Fisher et al. leg. ( CASC) ; 1w., 1s., Réserve Spéciale Ambatovaky, Sandrangato river, -16.77468 49.26551, 355 m, Fisher et al. leg. ( CASC) ; 1w., 1s., 1q., Réserve Spéciale Ambatovaky, Sandrangato river, -16.7633 49.26692, 520 m, Fisher et al. leg. ( CASC) ; 1w., 1s., Réserve Spéciale Ambatovaky, Sandrangato river, -16.7702 49.26638, 470 m, Fisher et al. leg. ( CASC) ; 1w., 1s., Réserve Spéciale Ambatovaky, Sandrangato river, -16.7755 49.26427, 430 m, Fisher et al. leg. ( CASC) ; 2w., 2s., Réserve Spéciale Ambatovaky, Sandrangato river, -16.81739 49.29402, 360 m, Fisher et al. leg. ( CASC) ; 4w., 3s., 1q., Réserve Spéciale Ambatovaky, Sandrangato river, -16.81745 49.2925, 400 m, Fisher et al. leg. ( CASC) ; 3w., 1m., Réserve Spéciale Ambatovaky, Sandrangato river, -16.80561 49.29507, 480 m, Fisher et al. leg. ( CASC) .

Geographic range. Madagascar, widely distributed in the central and eastern parts of the island.

Diagnosis. Major workers. Head in full-face view sub-rectangular, not widening posteriorly, with lateral margins relatively straight; side of head with dense, long, suberect to erect pilosity; medial frons with moderately dense and thick costulae; interspaces between costulae distinctly punctate; frons laterally with thick and sparse rugae; interspaces between rugae distinctly punctate; occipital lobes punctate, sometimes with additional sparse and weakly developed rugae; scape, when laid back, exceeding the midlength of head by one-fifth of its length; inner hypostomal tooth distinct, small, and bulge-like, with top arching posteroventrally; outer hypostomal tooth lobe-like, moderately high, and wide, with top directed posteriorly; median tooth absent; promesonotum moderately long, angular, and very low; posterior mesonotum smoothly declining towards propodeum; mesonotal process weakly developed and tubercle-like; mesosoma punctate; lateral sides of pronotum, propodeum, and katepisternum with additional thin rugae; gaster indistinctly shagreened; body yellowish brown to brown. Minor workers. Occiput slightly elongated; nuchal collar indistinct; head sculpture punctate, gena mostly or entirely 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 small and thin; mesosoma punctate; body yellowish brown.

Description. Major workers. Measurements (n=10): HL: 1.56–1.73 (1.62); HW: 1.49–1.66 (1.55); SL: 1.04– 1.18 (1.11); EL: 0.16–0.21 (0.19); WL: 1.54–1.68 (1.6); PSL: 0.19–0.27 (0.24); MTL: 1.14–1.38 (1.24); PNW: 0.52–0.65 (0.59); PTW: 0.15–0.18 (0.16); PPW: 0.36–0.45 (0.4); CI: 101.9–106.7 (104.4); SI: 69.3–75.6 (71.4); PSLI: 11.9–15.9 (15.1); PPI: 36.6–45.6 (40.9); PNI: 34.8–41.1 (38.0); MTI: 74.5–87.9 (79.8).

Head. In full-face view sub-rectangular, not widening posteriorly, with lateral sides relatively straight ( Fig. 20B ). In lateral view sub-oval, not depressed posteriorly; ventral and dorsal margins convex; inner hypostomal tooth visible. Side of head with dense, long, suberect to erect pilosity; head dorsum with relatively dense, long, suberect to erect pilosity. Medial frons with moderately dense and thick costulae; interspaces between costulae distinctly punctate. Frons laterally with thick and sparse rugae; interspaces between rugae distinctly punctate. Occipital lobes punctate, with sparse and sometimes weakly developed rugae. Gena with dense and moderately thick costulae; interspaces between costulae punctate. Sides posterolateral from eyes punctate and sometimes with additional network of thin and sparse rugulae. Center of clypeus shiny with weakly developed puncta, lateral sides with distinct rugulae; median notch present, moderately wide, and shallow; median longitudinal carina present; lateral longitudinal carinae present. Scape, when laid back, exceeding the midlength of head by one-fifth of its length; pilosity subdecumbent to erect ( Fig. 20B, D ). Inner hypostomal tooth distinct, small, and bulge-like, with top arching posteroventrally; outer hypostomal tooth lobe-like, moderately high, and wide, with top directed posteriorly; median tooth absent ( Fig. 27L ). Mesosoma. In lateral view, promesonotum moderately long, angular, and very low; posterior mesonotum smoothly declining towards propodeum; mesonotal process weakly developed and tuberclelike; promesonotal groove absent; metanotal groove indistinct; propodeal spines moderately long with narrow base, and acute top; humeral tubercle weakly produced ( Fig. 20D ). Surface punctate; lateral sides of pronotum, propodeum, and katepisternum with additional thin rugae. Pilosity dense, long, and erect ( Fig. 20D, F ). Gaster. Shiny and indistinctly shagreened; pilosity moderately sparse, long, and erect ( Fig. 20D, F ). Color. Yellowish brown to brown, antennae and legs usually brighter ( Fig. 20D, F ).

Description. Minor workers. Measurements (n=10): HL: 0.73–0.82 (0.78); HW: 0.49–0.57 (0.53); SL: 1.03– 1.17 (1.12); EL: 0.13–0.15 (0.14); WL: 1.02–1.14 (1.07); PSL: 0.11–0.14 (0.13); MTL: 0.9–1.07 (0.99); PNW: 0.37–0.42 (0.39); PTW: 0.07–0.11 (0.08); PPW: 0.14–0.2 (0.17); CI: 141.8–149.8 (147.0); SI: 200.6–216.2 (209.8); PSLI: 14.9–17.9 (16.2); PPI: 44.7–54.0 (50.4); PNI: 68.8–75.7 (72.6); MTI: 164.2–198.3 (185.6).

Head. In full-face view oval, posterior region slightly elongated; nuchal collar weakly developed ( Fig. 20A ). Pilosity relatively sparse, moderately long, subdecumbent to erect. Sculpture punctate, gena mostly or entirely 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. 20A, C ). Mesosoma. In lateral view, promesonotum low, long, and arched; promesonotal groove present; metanotal groove distinct; propodeal spines small, thin, and triangular ( Fig. 20C ). Sculpture punctate. Pilosity sparse, long, and erect ( Fig. 20C, E ). Gaster. With sparse and erect pilosity ( Fig. 20C, E ). Color. Yellowish brown ( Fig. 20C, E ).

Biology. The species was collected between 3–1490 m elevation, in rainforest, montane forest, littoral rainforest, montane rainforest, and montane shrubland. Nests were located in rotten logs, rotting tree stumps, and rotten sticks on the ground. Workers were collected from sifted litter, on low vegetation, and on tree trunks.

Comments. Pheidole oswaldi is most similar to sympatric P. decollata . Its major workers can be separated by moderately long, angular, and very low promesonotum and small inner hypostomal tooth. In contrast, majors of P. decollata have short, angular, and moderately low promesonotum and moderately large inner hypostomal tooth. Minors of P. oswaldi differ in slightly elongated posterior region of head and moderately long, angular, and very low promesonotum. Minor workers of P. decollata have posterior region of the head not elongated and the promesonotum is moderately long, moderately low, and angular.

Figures

FIGURE 20. Pheidole oswaldi, full-face view (A), profile (C), and dorsal view (E) of minor worker (CASENT0275335) and full-face view (B), profile (D), and dorsal view (F) of major worker (CASENT0923266).

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).