Crematogaster sewardi

This species has been found in a variety of habitats. Little is know about its biology.

Identification
Hosoishi and Ogata (2009) - 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
Crematogaster (P.) sewardi is the most wide-ranging species of the subgenus Physocrema. This species ranges from Thailand to Malaysia (Peninsula and Borneo) and to Indonesia (Kalimantan, Sumatra, Krakatau Island, Java, Bali and Lombok).

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

Nomenclature

 * . Crematogaster deformis r. sewardi Forel, 1901h: 64 (w.q.) BORNEO (no state data).
 * Type-material: lectotype worker (by designation of Hosoishi & Ogata, 2009b: 28), 1 paralectotype worker, 1 paralectotype queen.
 * Type-locality: lectotype Borneo: (no further data) (H. Seward); paralectotypes with same data.
 * Type-depository: MHNG.
 * Combination in C. (Physocrema): Emery, 1922e: 140.
 * Subspecies of difformis: Forel, 1907e: 17; Wheeler, W.M. 1919e: 75; Emery, 1922e: 140; Chapman & Capco, 1951: 102; Bolton, 1995b: 162.
 * Status as species: Hosoishi & Ogata, 2009a: 7 (redescription); Hosoishi & Ogata, 2009b: 28 (redescription); Pfeiffer, et al. 2011: 46; Khachonpisitsak, et al. 2020: 93.
 * Distribution: Indonesia (Bali, Java, Kalimantan, Krakatau, Lombok, Sumatra), Malaysia (Peninsula, Sabah, Sarawak), Thailand.

Worker
Hosoishi and Ogata (2009) - 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.

Type Material
Hosoishi and Ogata (2009) - LECTOTYPE worker (top specimen of two on one pin) (by present designation) and one paralectotype worker and queen from MALAYSIA: Borneo (H. Seward) [examined].

References based on Global Ant Biodiversity Informatics

 * Abe T., S. Yamane, and K. Onoyama. Ants collected on the Krakatau Islands 100 years after the great eruptions. Biogeography 14: 65-75.
 * Chapman, J. W., and Capco, S. R. 1951. Check list of the ants (Hymenoptera: Formicidae) of Asia. Monogr. Inst. Sci. Technol. Manila 1: 1-327
 * Donisthorpe H. 1941. Description of a new species of Crematogaster Lund, subgenus Physocrema Forel, with a list of, and a key to, the known species of the subgenus. Entomologist 74: 225-227.
 * Forel A. 1901. Formiciden des Naturhistorischen Museums zu Hamburg. Neue Calyptomyrmex-, Dacryon-, Podomyrma- und Echinopla-Arten. Mitt. Naturhist. Mus. Hambg. 18: 43-82.
 * Forel A. 1907. Formiciden aus dem Naturhistorischen Museum in Hamburg. II. Teil. Neueingänge seit 1900. Mitt. Naturhist. Mus. Hambg. 24: 1-20.
 * Hosoichi S., and K. Ogata. 2009. A taxonomic revision of the Asian endemic subgenus Physocrema of the genus Crematogaster (Hymenoptera: Formicidae). Zootaxa 2062: 15-36.
 * Hosoishi S. and K. Ogata. 2009. A check list of the ant genus Crematogaster in Asia (Hymenoptera: Formicidae). Bull. Inst. Trop. Agr. Kyushu Univ. 32: 43-83.
 * Hosoishi S., and K. Ogata. 2009. A taxonomic revision of the Asian endemic subgenus Physocrema of the genus Crematogaster (Hymenoptera: Formicidae). Zootaxa 2062: 15-36.
 * Hosoishi S.; and K. Ogata. 2009. The ant genus Crematogaster Lund, subgenus Physocrema Forel, in the Indochinese Peninsula. Asian Myrmecology 2 (2008): 1-10.
 * Hosoishi, S. and K. Ogata. 2008. The ant genus Crematogaster Lund, subgenus Physocrema Forel, in the Indochinese Peninsula (Hymenoptera: Formicidae). Asian Myrmecology 2:1-10.
 * Huong N. T. T., P. V. Sang, and B. T. Viet. 2015. A preliminary study on diversity of ants (Hymenoptera: Formicidae) at Hon Ba Nature Reserve. Environmental Scientific Conference 7: 614-620.
 * Pfeiffer M.; Mezger, D.; Hosoishi, S.; Bakhtiar, E. Y.; Kohout, R. J. 2011. The Formicidae of Borneo (Insecta: Hymenoptera): a preliminary species list. Asian Myrmecology 4:9-58
 * Tanaka H. O., S. Yamane, and T. Itioka. 2012. Effects of a fern-dwelling ant species, Crematogaster difformis, on the ant assemblages of emergent trees in a Bornean tropical rainforest. Ann. Entomol. Soc. Am. 105(4): 592-598.
 * Wheeler W. M. 1919. The ants of Borneo. Bulletin of the Museum of Comparative Zoology 63:43-147.
 * Yamane S. 2013. A Review of the ant fauna of the Krakatau Islands, Indonesia. Bull. Kitakyushu Mus. Nat. Hist. Hum. Hist. Ser: A, 11: 1-66
 * Zryanin V. A. 2011. An eco-faunistic review of ants (Hymenoptera: Formicidae). In: Structure and functions of soil communities of a monsoon tropical forest (Cat Tien National Park, southern Vietnam) / A.V. Tiunov (Editor). – M.: KMK Scientific Press. 2011. 277 р.101-124.