Crematogaster sewardi

Identification
Hosoishi and Ogata (2014) - This species is very similar to Crematogaster ampullaris, but can be distinguished by the dorsal outline of the mesosoma and the depth of the metanotal groove. The MHNG syntypes were lighter colored than normal, but otherwise match the characters of the specimens examined.

Among the Physocrema species, Crematogaster ampullaris, Crematogaster difformis, and C. (P.) sewardi are very similar to each other. Crematogaster (P.) sewardi is widely distributed in South East Asia, but almost all have been referred to as C. (P.) difformis in the past. It is also likely that C. (P.) sewardi has been misidentified as C. (P.) difformis in the literature (Attygalle et al. 1989; Gay & Hensen, 1992; Ito et al. 2001; Jaitrong & Nabhitabhata, 2005; Jones et al. 2005). Based on the key C. (P.) difformis can be easily distinguished from ampullaris and sewardi, but the latter two species are very similar to each other and have been frequently confused. Crematogaster (P.) difformis and C. (P.) sewardi are geographically sympartric in the Malay Peninsula and Borneo, whereas C. (P.) ampullaris and C. (P.) sewardi are allopatric. Crematogaster (P.) ampullaris is found in Sulawesi, Timor and Philippines, and C. (P.) sewardi in Indochina, Malay Peninsula, Borneo, Sumatra, Krakatau Island, Java, Bali and Lombok.

Distribution based on Regional Taxon Lists
Indo-Australian Region: Borneo, Indonesia, Krakatau Islands. Oriental Region: Vietnam.

Nomenclature

 *  sewardi. Crematogaster deformis r. sewardi Forel, 1901h: 64 (w.q.) BORNEO. Combination in C. (Physocrema): Emery, 1922e: 140. Raised to species: Hosoishi & Ogata, 2009a: 7. See also: Hosoishi & Ogata, 2009b: 28.

Worker
Hosoishi and Ogata (2014) - HW 0.85–1.32; HL 0.77–1.22; CI 105–111; SL 0.70–0.96; SI 72–83; EL 0.16–0.24; PW 0.51–0.74; WL 0.96–1.40; PSL 0; PtL 0.28–0.42; PtW 0.21–0.36; PtH 0.15–0.22; PpL 0.19–0.28; PpW 0.23–0.34; PtHI 52–57; PtWI 74–86; PpWI 113–129; WI 94–116 (Three workers measured).

Workers with pronounced size polymorphism.

Scape not reaching posterior corner of head in large workers.

In lateral view, dorsal profile of promesonotum convex; propodeum distinctly raised relative to promesonotum. Anterior margin of pronotal collar slightly concave in dorsal view. Metanotal groove convex posteriorly in dorsal view in large workers, deep and situated posteriorly to the posterior ridge of pronotum in lateral view; thorax strongly constricted in middle in dorsal view. In dorsal view, some longitudinal rugulae connecting between mesonotum and propodeum; the boundary distinct. Propodeal spiracle situated away from the metapleural gland orifice, the distance between them much greater than the propodeal spiracle diameter. Propodeal spines absent.

Clypeus sculptured with longitudinal rugulae.

Standing pilosity sparse on dorsal face of head, abundant on promesonotum. Dorsal face of head with decumbent setae. Clypeus with short setae. Fourth abdominal tergite with appressed setae. Dorsal setae on fourth abdominal tergite directed posteriorly.

Body color black.