Pheidole gracilis, Salata & Fisher, 2020

Salata, Sebastian & Fisher, Brian L., 2020, Taxonomic revision of the Pheidole sikorae species group (Hymenoptera, Formicidae) from Madagascar, ZooKeys 949, pp. 1-185 : 1

publication ID

https://dx.doi.org/10.3897/zookeys.949.51269

publication LSID

lsid:zoobank.org:pub:93BFA448-BB73-43CD-BC4E-A86090DA63D5

persistent identifier

https://treatment.plazi.org/id/687877F4-A954-4004-94E3-135722F8442A

taxon LSID

lsid:zoobank.org:act:687877F4-A954-4004-94E3-135722F8442A

treatment provided by

ZooKeys by Pensoft

scientific name

Pheidole gracilis
status

sp. nov.

Pheidole gracilis sp. nov. Figs 30A-F View Figure 30 , 63L View Figure 63 , 65L View Figure 65

Type material.

Holotype. Madagascar. • 1 major worker; Antsiranana; Parc National Montagne d’Ambre, 12.2 km 211°SSW Joffreville; -12.59639, 49.1595; alt. 1300 m; 2 Feb 2001; Fisher et al. leg.; montane rainforest, ex dead branch above ground; BLF02825; CASENT0403308, middle specimen on the pin (CASC). Paratypes. • 6w., 4s.; same data as for holotype, CASENT0403307, CASENT0872252, CASENT0403309, CASENT0403310 (CASC, MHNG, PBZT).

Other material.

Madagascar. - Antsiranana: •2w., 3s.; Parc National Montagne d’Ambre, 12.2 km 211°SSW Joffreville; -12.59639, 49.1595; alt. 1300 m; 2 Feb 2001; Fisher et al. leg.; montane rainforest, ex dead branch above ground; BLF02844 (CASC).

Diagnosis.

Moderately large species. Major workers. Head in full-face view sub-oval and not widening posteriorly, with anterior and posterior sides slightly convex, in lateral view sub-oval; ventral and dorsal faces convex; sides of the head with dense, short, decumbent to suberect pilosity; medial part of frons with moderately thick, longitudinal, interrupted, and moderately dense rugae, interspaces rugulate, rugae directed slightly outward on posteromedial part; occipital lobes predominantly smooth, only anterior part with indistinct, dense, thin, and longitudinal rugae; area posterolateral from eyes with indistinct, dense, thin, and longitudinal rugae, posteriormost part smooth; scape, when laid back, exceeding the midlength of head by approximately two-fifths of its length; inner hypostomal teeth distinct, low, closely spaced, triangular, with rounded apex directed upward; outer hypostomal teeth dentate, wider and higher then inner teeth; inner and outer hypostomal teeth closely spaced and connected by indistinct concavity; mesosoma distinctly foveolate; promesonotum with additional sparse and moderately thick, irregular to transverse rugae on dorsum; katepisternum with smooth notch; body yellowish orange. Minor workers. Head foveolate; vertex with additional, short, and transverse rugulae; area posterolateral from eyes with weaker sculpture that appears smooth; scape, when laid back, exceeding the posterior head margin by two-fifths of its length; promesonotum low and moderately long; promesonotal groove present; propodeal spines moderately large with narrow base; mesosoma foveolate; katepisternum with smooth notch; body yellow to orange.

Description.

Major workers. Measurements (N = 8): HL: 1.22-1.32 (1.27); HW: 1.22-1.33 (1.27); SL: 0.72-0.82 (0.77); EL: 0.16-0.19 (0.17); WL: 1.08-1.22 (1.15); PSL: 0.16-0.21 (0.18); MTL: 0.76-0.83 (0.79); PNW: 0.48-0.53 (0.51); PTW: 0.14-0.17 (0.16); PPW: 0.3-0.37 (0.33); CI: 97.3-103.5 (99.8); SI: 56.7-63.3 (60.7); PSLI: 12.8-16.9 (14.6); PPI: 43.1-55.8 (49.0); PNI: 38.8-41.4 (39.8); MTI: 59.3-65.7 (62.1).

Head. In full-face sub-oval, not widening posteriorly, with anterior and posterior sides slightly convex (Fig. 30B View Figure 30 ). In lateral view sub-oval; ventral and dorsal faces convex; inner hypostomal teeth visible. Sides of the head with dense, short, decumbent to suberect pilosity; whole head with dense, long, decumbent to erect pilosity. Medial part of frons with moderately thick, longitudinal, interrupted, and moderately dense rugae, interspaces rugulate, rugae directed slightly outward on posteromedial part; lateral sides with thick, dense, and longitudinal rugae with distinctly rugulate interspaces. Occipital lobes predominantly smooth, only anterior part with indistinct, dense, thin, and longitudinal rugae. Area posterolateral from eyes with indistinct, dense, thin, and longitudinal rugae, posteriormost part smooth and shiny. Gena with relatively sparse and thick longitudinal rugae and smooth to indistinctly rugulate interspaces. Centre of clypeus smooth and shiny, lateral sides with indistinct 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. 30B, D View Figure 30 ). Inner hypostomal teeth distinct, low, closely spaced, triangular, with rounded apex directed upward; outer hypostomal teeth dentate, wider and higher than inner teeth; inner and outer hypostomal teeth closely spaced and connected by indistinct concavity (Fig. 63L View Figure 63 ). Mesosoma. In lateral view, promesonotum short, angular, and moderately low, posterior mesonotum moderately steep, mesonotal process indistinct, tubercle-like; promesonotal groove absent; metanotal groove absent; propodeal spines moderately long, with narrow base and acute apex; humeral area weakly produced (Fig. 30D View Figure 30 ). Surface shiny and distinctly foveolate; promesonotum with additional sparse and moderately thick, irregular to transverse rugae on dorsum; katepisternum with smooth notch. Pilosity sparse, long, and erect (Fig. 30D, F View Figure 30 ). Petiole. Shiny with sparse foveolae; node finely foveolate, triangular, with rounded and thick apex, in rear view node dorsoventrally slightly concave; pilosity moderately sparse and erect (Fig. 30D, F View Figure 30 ). Postpetiole. Shiny and foveolate; dorsum with reduced sculpture and smooth notch; in dorsal view oval, lateral margins medially with two wide and dentate projections; pilosity long, moderately sparse, and erect (Fig. 30D, F View Figure 30 ). Gaster. Shiny and smooth; pilosity moderately sparse, moderately long, and erect (Fig. 30D, F View Figure 30 ). Colour. Yellowish orange with yellow legs (Fig. 30D, F View Figure 30 ).

Minor workers. Measurements (N = 10): HL: 0.65-0.71 (0.69); HW: 0.55-0.58 (0.56); SL: 0.69-0.74 (0.71); EL: 0.12-0.14 (0.13); WL: 0.84-0.89 (0.86); PSL: 0.1-0.12 (0.11); MTL: 0.58-0.66 (0.61); PNW: 0.36-0.4 (0.38); PTW: 0.07-0.1 (0.09); PPW: 0.15-0.19 (0.16); CI: 118.3-123.9 (121.5); SI: 123.7-132.8 (126.8); PSLI: 15.0-17.8 (16.3); PPI: 49.7-66.0 (57.0); PNI: 65.1-69.6 (67.4); MTI: 103.8-112.7 (108.9).

Head. Cephalic margin slightly convex (Fig. 30A View Figure 30 ). Pilosity relatively sparse, moderately long, decumbent to subdecumbent. Sculpture shiny and foveolate; vertex with additional, short, and transverse rugulae; area posterolateral from eyes with weaker sculpture that appears smooth; antennal sockets with few thick, curved outward rugae and foveolate interspaces. 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, suberect to erect (Fig. 30A, C View Figure 30 ). Mesosoma. In lateral view, promesonotum low and moderately long, arched; promesonotal groove present; metanotal groove distinct; propodeal spines moderately large with narrow base, triangular (Fig. 30C View Figure 30 ). Sculpture shiny and foveolate; katepisternum with smooth notch. Pilosity very sparse, moderately long, and erect (Fig. 30C, E View Figure 30 ). Gaster. With sparse, erect pilosity (Fig. 30C, E View Figure 30 ). Colour. Orange to yellow (Fig. 30C, E View Figure 30 ).

Etymology.

Latin for slender in reference to body sculpture.

Biology.

The species was collected at 1300 m in elevation, in montane rainforest. Nests were located in dead branches above ground.

Comments.

Pheidole gracilis sp. nov. is a member of a group of species characterised by distinctly reduced head sculpture in major workers with occipital lobes entirely or predominantly smooth, area posterolateral from eyes partially or entirely smooth and shiny or with reduced sculpture and smooth notches. The group consists of four species: P. litigiosa , P. masoandro sp. nov., P. gracilis sp. nov., and P. tampony sp. nov. Pheidole gracilis sp. nov. is known only from Parc National Montagne d’Ambre in Antsiranana and its distribution doesn’t overlap with other members of this group. Morphologically the species is most similar to P. litigiosa , known from the vicinity of Antananarivo, and P. masoandro sp. nov., described from Anosyenne Mts. in Toliara. Its major workers can be easily separated from both of those taxa based on more developed head sculpture with occipital lobes anteriorly covered by indistinct, dense, thin, and longitudinal rugae and distinctly foveolate promesonotum; minor workers can be separated based on foveolate mesosoma and low and long promesonotum. Minor workers of P. gracilis sp. nov. are similar to minors of P. tampony sp. nov. and P. befotaka sp. nov. but can be separated based on more developed head sculpture with additional, short, and transverse rugulae on vertex and area posterolateral from eyes with weak but distinct sculpture and lacking smooth notches.

Kingdom

Animalia

Phylum

Arthropoda

Class

Insecta

Order

Hymenoptera

Family

Formicidae

Genus

Pheidole