Hypoponera Santschi 1938

Hypoponera Santschi, 1938 (Figs 2A, 4A, 6A) Recognition. Small ants, measuring 2.2–3.2 mm in total body length; mandible without basal pit; mid- and hindtibiae apicoventrally with pectinate spur only; subpetiolar process without anterior fenestra. Description. Small ants, measuring 2.2–3.2 mm in total body length and 0.40–0.66 mm in head width. Head longer than broad, with posterior margin straight to very shallowly emarginate. Clypeus with anterior margin straight to shallowly concave, and with median longitudinal blunt swelling. Malar space generally shorter than half major diameter of eye, with exception of H. beppin, in which it is slightly longer. Eye generally large, comprising 12–16 ommatidia on its longest axis, with moderately-set to dense short hairs. Mandible with distinct teeth along masticatory margin (in at least apical 3/4) except for H. beppin Terayama, 1999 and probably H. zwaluwenbergi (Wheeler, 1933), in which basal half or more of masticatory margin serrate without distinct teeth; basal pit or groove absent.Antennal scape either fails to reach posterior margin of head or slightly extends beyond it. With mesosoma in dorsal view promesonotum slightly to distinctly narrower than head; parapsidal line generally faint and parascutal carina distinct on mesoscutum; scutoscutellar sulcus very ‘narrow’; metanotum ‘narrow’ strip defined anteriorly and posteriorly by shallow sutures. Propodeal spiracle with elongate or slit-like opening. Petiole scale-like or node-like; subpetiolar process without anterior fenestra. Prora small scale often margined with pigmented rim. Constriction between gastral segments I and II weak; most of pretergite of gastral segment II generally unexposed, while presternite often extensively exposed; cinctus cross-ribbed (forming a chain of punctures). Sting relatively short, extending from tip of gaster by length of last tergite (often invisible from outside). Midtibia without strong bristles; ventral apices of mid- and hindtibiae with pectinate spur only. Wings fully developed except for ergatoid queens in some species; hindwing lacking jugal lobe. Caste differences. The queen is similar to the worker in habitus and sculpture except for the mesosoma of the former having wings and associated structures on the meso- and metathorax, much larger eyes and complete set of ocelli (but see Remarks). Remarks. The queens of the Japanese Hypoponera species are recognized among the Japanese genera by the character combination mentioned in Recognition above. Four Japanese species have been reported to have ergatoid queens (TERAYAMA et al. 2014): H. nubatama Terayama & Hashimoto, 1996, H. opacipes (Mayr, 1887), H. punctatissima (Roger, 1859) and H. ragusari (Emery, 1894). Caste system and behavior of one of them, H. nubatama, was studied by HASHIMOTO (1995), HASHIMOTO et al. (1995), TERAYAMA & HASHIMOTO (1996) and YAMAUCHI et al. (2001). This species has both winged and apterous queens (ergatoids) and also winged and apterous males; ergatoid queens are similar to workers but distinguished from the latter by much larger eyes, frequent possession of anterior ocellus and a thicker petiole (see also Discussion). Species examined (5/8). Hypoponera beppin Terayama, 1999, H. nippona Santschi, 1937, H. nubatama Terayama & Hashimoto, 1996, H. punctatissima (Roger, 1859) (= H. ergatandris sensu SEIFERT 2013), H. sauteri Onoyama, 1989.