Tetramorium nipponense Wheeler, 1928

Yamane 1, Seiki, Hosoishi 2, Shingo & Ito 3, Fuminori, 2022, Japanese Tetramorium queens: identification key and species diagnoses (Hymenoptera, Formicidae, Myrmicinae), ZooKeys 1084, pp. 43-64 : 43

Tetramorium nipponense Wheeler, 1928

Figs 1j, m , 2d , 4d , 5d

Queen diagnosis.

Measurements (n = 5): TBL 3.5-4 (3.8), HL 0.83-0.86 (0.85), HW 0.69-0.76 (0.72), SL 0.54-0.58 (0.56), EL 0.23-0.25 (0.24), EW 0.18-0.2 (0.19), PtW 0.28-0.33 (0.3), PptW 0.36-0.41 (0.39), CI 82.4-88.4 (85.1), SI 74.7-80 (77.6), ELI 27.1-29.8 (28.1). Body yellowish-brown, with gaster slightly darker; coxae, femora and tibiae of all legs creamy yellow. Head distinctly longer than broad. Head reticulate, except for frons between clypeus and ocellar area with a few longitudinal carinae; clypeus superficially sculptured and shiny, with three longitudinal carinae. Mandible densely striate. Pronotal dorsum coarsely reticulate; mesonotum longitudinally striate/rugose; propodeum irregularly sculptured and shiny; transverse carinae between propodeal spines absent or weak (at most only one distinct carina present). Lateral face of mesosoma coarsely rugose except for lower portion of mesopleuron weakly sculptured; propodeal spine slender, often weakly up-curved apically. Nodes of petiole and postpetiole entirely puncto-reticulate. Gastral tergite 1 with longitudinal basal striae. Antennal scape and mid- and hind-tibiae with many decumbent to near suberect hairs.

Caste difference.

Worker measurements (n = 5): TBL 2.8-3.0 (2.9), HL 0.74-0.79 (0.77), HW 0.63-0.7 (0.66), SL 0.49-0.55 (0.53), EL 0.16-0.18 (0.17), EW 0.12-0.14 (0.13), PtW 0.23-0.26 (0.25), PptW 0.28-0.33 (0.30), CI 84.0-88.6 (86.4), SI 75.4-85.7 (80.2), ELI 24.6-27.3 (25.9). Worker very similar to the queen in coloration, structure and sculpture, with the following differences. Body smaller. Eye smaller, distance between anterior margin of eye and mandibular base slightly longer than major diameter of eye; in the queen, the distance slightly shorter than major diameter of eye. Dorsum of mesosoma entirely coarsely reticulate; in the queen, mesonotum with longitudinal rugae/striae that are dense and often irregular. Lower portion of mesopleuron sculptured and slightly mat; in the queen, lower portion with much weaker sculpture and shiny. Propodeal spine up-curved in apical 1/3; in the queen, the spine tending to be straighter throughout. Petiole tends to be longer than in the queen. Long hairs on antennal scape and mid- and hind-tibiae frequently near-suberect; in the queen, these hairs less frequently near suberect.

Specimens examined.

Kyushu: 1q (dealate), Umi-jinja, Shikano-shima, Fukuoka-shi, 15.ix.1980, K. Ogata leg. (Figs 2d , 4d , 5d ); 6q (winged), Yoshino-chô, Kagoshima-shi, 7.ix.2016, attracted to light, T. Tsukada leg.; 3q (dealate), Kenkôno-mori, Inusako-chô, Kagoshima-shi, 20.iv.2019, dry dead twig on ground, Sk. Yamane leg. (JP19-SKY-022); 3q (dealate), near Hetsuka, Minamiôsumi-chô, Kagoshima-ken, 23.vii.2020, nest under moss, Sk. Yamane leg. (JP20-SKY-069). N. Ryukyus: 1q (dealate), Tashiro-Yumugi, Kuchinoerabu-jima, Ôsumi Islands, 26.vii.2016, nest in dead sasa bamboo, Sk. Yamane leg. (JP16-SKY-70); 2q (dealate), Maeda, Kuchinoerabu-jima, in dead twig on ground, Sk. Yamane leg. (JP16-SKY-120). C. Ryukyus: 1q (dealate), Nagakumo, Tatsugô-chô, Amami-ôshima, Amami Islands, 22.xii.2015, in decayed wood, Sk. Yamane leg. (JP15-SKY-72); Takahachi-yama, Amami-ôshima, 5.iii.2017, in decayed wood, Sk. Yamane leg. (JP17-SKY-20); 7q (winged), Chinase, Naze, Amami-ôshima, 28.viii.2019, attracted to light, K. Kanai leg.; 3q (2 winged, 1 dealate), Yonaha, Okinawa-jima, 5.vii-5.viii.2001, Malaise trap, T. Muroi & C. Nakamura.

Distribution

in Japan. Honshu (southern coast), Shikoku, Kyushu, throughout Nansei Islands, Senkaku Islands.

Remarks.

Tetramorium nipponense belongs to the T. bicarinatum species group ( Bolton 1977) together with T. bicarinatum in Japan. The gaster is generally much paler in colour than in the latter. The shape of the petiole that is frequently used to distinguish between these species in the worker caste is not very useful in the queen, though in T. nipponense the petiole tends to be longer and have a weakly convex dorsal face (for further discussion, see Remarks under T. bicarinatum ). Queens of this species are frequently attracted to light and also caught with Malaise traps.

Figures

Figure 1. Some important characters used in the key to species a-e petiole in profile view a T. pacificum b T. lanuginosum c T. bicarinatum d T. smithi e T. tsushimae f-h anterior half of first gastral tergite f T. bicarinatum g T. simillimum h T. lanuginosum i-k antennal scape showing pilosity on its anterior margin l-n left hindtibia i, l T. cf. kraepelini j, m T. nipponense k, n T. simillimum o, p configuration of ocelli o T. tanakai p T. cf. kraepelini.

Figure 2. Japanese Tetramorium queens: habitus in profile view a T. bicarinatum (Nagashima, Kagoshima-ken, Kyushu) b T. cf. kraepelini (Itoman, Okinawa-jima, Okinawa-ken) c T. lanuginosum (Komi, Iriomote-jima, Okinawa-ken) d T. nipponense (Umi-jinja, Shikano-shima, Fukuoka-shi) e T. pacificum (Upper Thompson Nature Park, Singapore) f T. simillimum (Yoron-jima, Amami Is., Kagoshima-ken). (Same specimens were used for ' head in full-face view' and ' habitus in dorsal view').

Figure 4. Japanese Tetramorium queens: head in full-face view a T. bicarinatum b T. cf. kraepelini c T. lanuginosum d T. nipponense e T. pacificum f T. simillimum g T. smithi h T. tanakai i T. tsushimae.

Figure 5. Japanese Tetramorium queens: habitus in dorsal view a T. bicarinatum b T. cf. kraepelini c T. lanuginosum d T. nipponense e T. pacificum f T. simillimum.