Physocrema Forel

Hosoishi, Shingo & Ogata, Kazuo, 2009, A taxonomic revision of the Asian endemic subgenus Physocrema of the genus Crematogaster (Hymenoptera: Formicidae), Zootaxa 2062, pp. 15-36 : 17-18

The subgenus Physocrema Forel

Physocrema Forel, 1912: 220 [as subgenus of Crematogaster ]. Type-species: Crematogaster inflata , by subsequent designation of Wheeler 1913: 82.

Physocrema as genus: Soulié, 1964: 398.

Physocrema as junior synonym of Crematogaster: Brown, 1973: 183 [provisional]; Smith, D. R. 1979: 1376; Hölldobler & Wilson, 1990: 13.

Physocrema as subgenus of Crematogaster: Forel, 1912: 220 ; Forel, 1917: 242; Emery, 1922: 139; Wheeler,W. M. 1922: 662; subsequent authors except those above; Bolton, 1995: 42.

Diagnosis of worker. Head subquadrate, slightly broader than long, with weakly concave posterior margin, angular posterior corners and subparallel sides. Occipital carinae developed. Mandible striate, with four teeth in small workers and five in larger workers, apical and subapical teeth large. Anterior margin of clypeus convex with slightly impressed median portion ( Figs 1, 2 ); anterolateral margins of clypeus protruded anteriorly, resulting in an appearance of the anterolateral and anteromedian margins being at about the same level ( Figs 1, 2 ); posterior margin of clypeus rounded between frontal lobes. Frontal carinae almost parallel. Antennae 11 segmented; antennal club 4-jointed. Compound eyes large but not distinctly projecting beyond lateral margins of head in full face view.

Pronotum and mesonotum usually without defined suture, rarely promesonotal suture present in large workers. Mesothoracic spiracle reduced to form small pit dorsoventrally. Variable extent of posterior mesosoma enlarged and swollen ( Figs 3, 4). Metapleural gland opening circular; propodeal spiracle facing posterolaterally ( Figs 3, 4).

Petiole flattened without node nor subpetiolar process; spiracle situated anteriorly midway between dorsal and ventral margins of petiole in lateral view, directed laterally; in dorsal view, elliptical with convex sides, longer than broad (Fig. 5). Postpetiole without distinctly longitudinal median sulcus, weakly bilobed behind in large workers (Fig. 5); spiracle situated distinctly anteriorly on the lateral surface.

Comments. Workers of the subgenus Physocrema can be distinguished from those of all other subgenera of Crematogaster by the features of (1) anteromedian margin of clypeus convex with slightly impressed median portion; (2) anterolateral margins of clypeus produced anteriorly; (3) 4-jointed antennal club (but, 3- jointed in mucronata ); (4) propodeum swollen; (5) metapleural gland orifice circular; (6) petiole elliptical; (7) petiole without node-like process posteriorly. The subgenus is unique among Asian Crematogaster ants in having features (4), (5), (6) and (7). The workers of the subgenus Physocrema share features (1), (2), (3) and (7) with the subgenus Paracrema . In Asian Crematogaster specimens examined, the workers of the subgenera Crematogaster , Decacrema , Mesocrema , Oxygyne , Paracrema , Physocrema and Xiphocrema share features (2) and (7).

Distribution. Southeast Asia: Vietnam (southern parts), Laos, Cambodia, Thailand, Myanmar (southeastern parts), Malaysia (Peninsula and Borneo), Singapore, Indonesia (Sumatra, Mentawai, Java, Bali, Lombok, Kalimantan, Sulawesi, Timor), Philippines ( Fig. 21 ).

Figures

FIGURES 1 − 2. Clypeus in dorsal view: 1 — C. (P.) inflata; 2 — C. (P.) aurita. White arrow indicates anterolateral margin of clypeus.

FIGURES 21 – 26. Distribution of Physocrema species in Southeast Asia. 21 — All Physocrema species; 22 — C. (P.) ampullaris; 23 — C. (P.) aurita; 24 — C. (P.) difformis; 25 — C. (P.) inflata; 26 — C. (P.) mucronata.