Ponera Latreille, 1804

Ponera Latreille, 1804 View in CoL

( Figs 1F View Fig , 3E View Fig , 5E View Fig , 7E View Fig )

Recognition. Body color various; small ants with total length 2.2–4.4 mm; mandible without basal pit; petiole node-like to squamiform, generally thick, with anterior fenestra and often also with paired posterior processes; mid- and hindtibiae apicoventrally with pectinate spur only. Description of queen. Small ants, measuring 2.2–4.4 mm in total body length and 0.44–0.80 mm in head width. In full-face view, head longer than broad, with almost straight to shallowly emarginate posterior margin, straight to weakly convex lateral margin and rounded posterolateral corner. Malar space slightly shorter than, subequal to, or slightly longer than half major diameter of eye. Clypeus only weakly convex anteriorly. Mandible elongate-triangular, without basal pit; three apical teeth large; basal half or more of masticatory margin serrate. Eye round with ca. 9–18 ommatidia along longest axis, with dense short hairs; with head in full-face view outer margin of eye hardly or slightly breaking lateral margin of head. Antennal scape either failing to reach posterior margin of head or slightly extending beyond it. With mesosoma in dorsal view promesonotum slightly narrower than head; mesoscutum with weak or distinct parapsidal line; parascutal carina blunt to absent. Opening of propodeal spiracle oval. Petiole node-like to squamiform, generally thick; tergite separated from sternite with deep sulcus flanked with sharply defined carinae; subpetiolar process with anterior fenestra, generally also with paired posterior spines ( Fig. 1C View Fig ). Prora small, thin scale margined with rim. Gastral constriction moderate; pretergite and presternite of gastral segment II punctate or irregularly striate; sculpture on presternite often stronger than on pretergite; cinctus generally distinctly defined, cross-ribbed (forming chain of coarse punctures). Mid- and hindtibiae apicoventrally with a pectinate spur only. Hindwing without jugal lobe. For the queen of P. kohmoku Terayama, 1996 and P. tamon Terayama, 1996 , see TERAYAMA (1996: Figs 1–3 View Fig View Fig View Fig , 10–12).

Caste differences. The worker is slightly smaller than the queen (TL: 1.6–3.5 mm vs. 2.2–4.4 mm; HW: 0.33–0.75 vs. 0.44–0.80). The eye is much smaller in the worker than in the queen, even vestigial in some species, generally consisting of one to a few ill-defined ommatidia. Ponera kohmoku is exceptional in this respect; the worker eye is relatively large with ca. 8 ommatidia along the longest axis of the eye (in total more than 20), but in the queen the number is much larger, i.e., 18–20 along the longest axis. In the worker the malar space is as long as the major diameter of the eye, while in the queen it is much shorter than eye length.

Remarks. Ponera is one of the two Japanese ponerine genera with an anterior fenestra on the petiolar sternite, the other being Parvaponera . However, it is easily separated from the latter by the reduced number of spurs (one) on the apicoventral part of the mid- and hindtibiae ( Parvaponera has two), the masticatory margin of the mandible serrate in its basal half (in the latter the entire masticatory margin is provided with strong teeth), and the ‘broader’ scutoscutellar sulcus that is narrowed medially (in the latter the scutoscutellar sulcus is linear over most of its length).

Species examined (5/8). Ponera bishamon Terayama, 1996 , P. kohmoku Terayama, 1996 , P.scabra Wheeler, 1928 , P. takaminei Terayama, 1996 , P. tamon Terayama, 1996 .