Taxonomic revision of the Pheidole sikorae species group (Hymenoptera, Formicidae) from Madagascar Author Salata, Sebastian Department of Entomology, California Academy of Sciences, San Francisco, CA 94118, USA https://orcid.org/0000-0003-0811-2309 sdsalata@gmail.com Author Fisher, Brian L. Department of Entomology, California Academy of Sciences, San Francisco, CA 94118, USA https://orcid.org/0000-0002-4653-3270 text ZooKeys 2020 949 1 185 http://dx.doi.org/10.3897/zookeys.949.51269 journal article http://dx.doi.org/10.3897/zookeys.949.51269 1313-2970-949-1 93BFA448BB7343CDBC4EA86090DA63D5 303D64593B3B550DBB7CE01AA547409D Pheidole parvula sp. nov. Figs 49A-F , 64G , 66K Type material. Holotype. Madagascar. • 1 major worker; Toamasina; Ankerana; -18.40062 , 48.81311 ; alt. 865 m; 17 Jan 2012; B. L. Fisher et al. leg.; rainforest, ex rotten log; BLF27754; CASENT0274865 (CASC). Paratype. • 1w.; same data as for holotype, CASENT0923270 (CASC). Figure 49. Pheidole parvula sp. nov., full-face view ( A ), profile ( C ), and dorsal view ( E ) of paratype minor worker (CASENT0923270) and full-face view ( B ), profile ( D ), and dorsal view ( F ) of holotype major worker (CASENT0274865). Other material. Madagascar. - Antananarivo : •1w., 1s.; Reserve Speciale d'Ambohitantely ; -18.22444 , 47.2774 ; alt. 1490 m; 9 Mar 2012; B. L. Fisher et al. leg.; montane forest, ex litter; BLF28300 (CASC). - Toamasina : •1w., 1q.; Ankerana; -18.40829 , 48.82107 ; alt. 750 m; 21 Jan 2012; B. L. Fisher et al. leg.; rainforest, ex rotten log; BLF27962 (CASC). Diagnosis. Minute species. Major workers. HL <0.9 mm and WL <0.8 mm; head in full-face view sub-oval, slightly widening posteriorly, with anterior and posterior sides convex, in lateral view sub-oval; ventral and dorsal faces convex; body dark orange; sides of head with moderately dense, moderately long, suberect pilosity; entire head distinctly sculptured, medial part of frons with thick and dense rugae and distinctly rugulate interspaces, rugae predominantly irregular and only centre and basal parts with few longitudinal rugulae; scape, when laid back, exceeding the midlength of head by one-fifth of its length; pronotum distinctly foveolate with additional irregular rugae on dorsum; anepisternum, katepisternum, and propodeum with fine rugulae and smooth interspaces; inner hypostomal teeth distinct, large, closely spaced, triangular, with rounded apex directed upward; outer hypostomal teeth lobe-like, slightly lower and wider than inner teeth; inner and outer hypostomal teeth moderately closely spaced and not connected by concavity; base of first gastral tergite smooth. Minor workers. HL <0.5 mm and WL <0.6 mm, scape, when laid back, surpassing the posterior head margin by one-fifth of its length; propodeal spines small and triangular; head relatively oval; body dark yellow; medial frons smooth; lateral sides of frons and vertex with fine, sparse, and irregular rugulae with smooth interspaces; area posterolateral from eyes smooth; mesosoma predominantly smooth with very sparse, fine, and irregular rugulae. Description. Major workers. Measurements ( N = 2): HL: 0.86, 0.91; HW: 0.88, 0.9; SL: 0.49, 0.51; EL: 0.11, 0.12; WL: 0.79, 0.83; PSL: 0.15, 0.16; MTL: 0.48, 0.46; PNW: 0.43, 0.43; PTW: 0.09, 0.15; PPW: 0.28, 0.32; CI: 97.6, 101.7; SI: 56.1, 57.1; PSLI: 17.8, 17.8; PPI: 31.8, 45.3; PNI: 48.5, 48.2; MTI: 54.3, 51.7. Head. In full-face view sub-oval, slightly widening posteriorly, with anterior and posterior sides convex (Fig. 49B ). In lateral view sub-oval; ventral and dorsal faces convex; inner hypostomal teeth visible. Sides of the head with moderately dense, moderately long, suberect pilosity; whole head with dense, long, decumbent to erect pilosity. Medial part of frons with thick and dense rugae and distinctly rugulate interspaces, rugae predominantly irregular and only centre and basal parts with few longitudinal rugulae; lateral sides with thick, dense, and irregular rugae, interspaces shiny and distinctly rugulate. Occipital lobes with denser, irregular rugae and distinctly rugofoveolate interspaces. Area posterolateral from eyes with thick, dense, and irregular rugae, interspaces shiny and distinctly rugulate, posteriormost part distinctly foveolate with few thick, irregular rugae. Gena with relatively sparse, thick, and longitudinal rugae and indistinctly rugoreticulate interspaces. Centre of clypeus smooth and shiny, lateral sides with indistinct rugulae; median notch present, moderately wide, and shallow; median longitudinal carina present; lateral longitudinal carinae absent. Scape, when laid back, exceeding the midlength of head by one-fifth of its length; pilosity subdecumbent to erect (Fig. 49B, D ). Inner hypostomal teeth distinct, large, closely spaced, triangular, with rounded apex directed upward; outer hypostomal teeth lobe-like, slightly lower and wider than inner teeth; inner and outer hypostomal teeth moderately closely spaced and not connected by concavity (Fig. 64G ). Mesosoma. In lateral view, promesonotum short, angular, and moderately low, posterior mesonotum moderately steep, mesonotal process very indistinct, tubercle-like, or absent; promesonotal groove absent; metanotal groove absent; propodeal spines long, with moderately narrow base and acute apex; humeral area laterally weakly produced (Fig. 49D ). Surface shiny; pronotum distinctly foveolate with additional irregular rugae on dorsum; anepisternum, katepisternum, and propodeum with fine rugulae and smooth interspaces. Pilosity moderately dense, long, and erect (Fig. 49D, F ). Petiole. Shiny with fine foveolae; node smooth to finely foveolate, triangular, with rounded and thick apex, in rear view node dorsoventrally straight to slightly convex; pilosity moderately sparse and erect (Fig. 49D, F ). Postpetiole. Shiny and foveolate; dorsum with reduced sculpture; in dorsal view oval, lateral margins medially with two dentate projections; pilosity long, moderately sparse, and erect (Fig. 49D, F ). Gaster. Shiny and smooth; pilosity dense, moderately long, and erect (Fig. 49D, F ). Colour. Dark orange; mandibles and gaster brown (Fig. 49D, F ). Minor workers. Measurements ( N = 3): HL: 0.45-0.49 (0.47); HW: 0.4-0.43 (0.42); SL: 0.43-0.45 (0.44); EL: 0.09-0.1 (0.09); WL: 0.55-0.59 (0.57); PSL: 0.05-0.05 (0.05); MTL: 0.34-0.36 (0.35); PNW: 0.27-0.29 (0.28); PTW: 0.06-0.07 (0.06); PPW: 0.09-0.1 (0.1); CI: 111.5-116.3 (113.5); SI: 103.0-108.5 (106.3); PSLI: 9.3-11.2 (10.1); PPI: 64.6-71.0 (67.3); PNI: 65.8-68.1 (66.9); MTI: 82.9-85.8 (84.3). Head. Cephalic margin indistinctly concave to straight (Fig. 49A ). Pilosity relatively dense, moderately long, decumbent to suberect. Sculpture shiny; medial frons smooth; lateral sides of frons and vertex with fine, sparse, and irregular rugulae with smooth interspaces; area posterolateral from eyes smooth; antennal sockets with few thick, curved outward rugae and indistinctly foveolate interspaces. Clypeus with median longitudinal carina absent; two lateral longitudinal carinae absent. Scape, when laid back, surpassing the posterior head margin by one-fifth of its length; pilosity dense, subdecumbent to erect (Fig. 49A, C ). Mesosoma. In lateral view, promesonotum moderately high and short, arched; promesonotal groove absent; metanotal groove distinct; propodeal spines small and triangular (Fig. 49C ). Sculpture shiny and predominantly smooth with very sparse, fine, and irregular rugulae. Pilosity moderately sparse, moderately long, and erect (Fig. 49C, E ). Gaster. With sparse, erect pilosity (Fig. 49C, E ). Colour. Dark yellow, gaster and vertex brownish (Fig. 49C, E ). Etymology. Latin for small in reference to the body size. Biology. The species was collected between 750-1490 m in elevation, in montane forest and rainforest. Nests were located in rotten logs and litter. Comments. Pheidole parvula sp. nov. belongs to the group of species characterised by small body size (major workers: HL <1.05 mm, WL <0.9 mm and minor workers HL <0.5 mm, WL <0.6 mm), head sub-oval and slightly widening posteriorly with anterior and posterior sides convex in major workers, and minor workers with yellow to brown body colouration and head foveolate or predominantly smooth and relatively oval. The group includes six species: P. havoana sp. nov., P. kely sp. nov., P. parvula sp. nov., P. parvulogibba sp. nov., P. volontany sp. nov., and P. midongy sp. nov. Within this group, P. parvula sp. nov., described form two localities, Reserve Speciale d'Ambohitantely in Antananarivo and Ankerana in Toamasina, is most similar to parapatric P. kely sp. nov. P. parvula sp. nov. may also be confused with two taxa known only from the Anosyenne Mts. in Toliara, P. parvulogibba sp. nov. and P. havoana sp. nov. Minor workers of P. parvula sp. nov. distinctly differ from P. kely sp. nov. and P. havoana sp. nov. in never foveolate head; and from P. parvulogibba sp. nov. in lateral sides of frons and vertex with fine, sparse and irregular rugulae with smooth interspaces. Major workers of P. parvula sp. nov. differ from P. kely sp. nov. and P. parvulogibba sp. nov. by medial part of frons with thick and dense rugae and distinctly rugulate interspaces; and differ from P. havoana sp. nov. in promesonotum foveolate with sparse, thick to moderately thick, transverse to irregular rugae on dorsum and lack of smooth notches.