Tetramorium bicarinatum (Nylander, 1846)

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 bicarinatum (Nylander, 1846)

Figs 1c , 2a , 4a , 5a

Queen diagnosis.

Measurements (n = 5): TBL 3.9-4.9 (4.4), HL 1.04-1.09 (1.06), HW 0.9-0.95 (0.94), SL 0.64-0.70 (0.68), EL 0.28 (0.28), EW 0.23-0.26 (0.24), PtW 0.39-0.42 (0.41), PptW 0.50-0.52 (0.51), CI 85.7-91.6 (89.0), SI 67.1-75.5 (71.8), ELI 25.7-26.9 (26.5). Head and mesosoma yellowish-brown; gaster blackish-brown. Dorsum of head between frontal carinae with distinct rugae that are weakly waved. Clypeus with three longitudinal carinae; anterior margin with median notch (impression). Vertex, temple, gena, pronotum and nodes of petiole and postpetiole coarsely reticulate. Mandible densely striate. Antennal scape with long decumbent/suberect hairs. Mesonotum covered with rather regular longitudinal rugae. Posterior declivity of propodeum with 2-3 distinct transverse carinae between propodeal spines. Dorsum of petiole and postpetiole coarsely reticulate. Gastral tergite 1 with fine, dense longitudinal striae at base.

Caste difference.

Worker measurements (n = 5): TBL 2.5-3.3 (3.0), HL 0.83-0.94 (0.88), HW 0.7-0.8 (0.74), SL 0.56-0.61 (0.58), EL 0.18-0.21 (0.19), EW 0.16-0.18 (0.17), PtW 0.24-0.28 (0.26), PptW 0.31-0.37 (0.34), CI 81.9-85.3 (84.1), SI 76.3-81.4 (79.1), ELI 20.9-22.7 (21.8). Worker much smaller than the queen. Eye smaller; distance between mandibular base and anterior margin of eye longer than major diameter of eye; in the queen, the distance as long as or shorter than major diameter of eye. Mandible more weakly striate and more shiny than in the queen. Entire dorsum of mesosoma puncto-reticulate; in the queen mesonotum longitudinally rugose. Propodeal spine slender and always up-curved apically; in the queen it tends to be more strongly sclerotised, relatively shorter, with broader base than in the worker and apex not distinctly up-curved. 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 mainland: 2q (dealate), Kyushu Univ. Hakozaki Campus, Fukuoka-shi, emerged from colony collected in ix. 2015 by M. Obika and kept in lab; 1q (dealate), Hongôkitakata, Miyazaki-shi, 21.vii.2020, Sk. Yamane & G. Mita; 1q (dealate), Naga-shima, Kagoshima-ken, 31.vii.1979, K. Ogata (Figs 2a , 4a , 5a ); 4q (dealate), Kagoshima Univ. Kôrimoto Campus, Kagoshima-shi, 7.vi.2005, rotting log, Sk. Yamane leg. (JP05-SKY-101); 1q (winged), Kamitaniguchi, Kagoshima-shi, 16.ix.2008, attracted to light, Sk. Yamane leg. N. Ryukyus: 1q (dealate), Nakano-shima, Tokara Islands, 31.iii.1991, Y. Yamanouchi leg. C. Ryukyus: 2q (dealate), Takabaru, Yoro-shima, Amami Islands, 2.vii.2015, dead stem on tree, Sk. Yamane leg. (JP15-SKY-34); 1q (dealate), Shuri, Okinawa-jima, 17.vii.2020, in house, Y. Kusui leg.

Distribution

in Japan. Honshu (Pacific coast), Shikoku, Kyushu, throughout the Nansei Islands, Ogasawara Islands and Iwô Islands ( Terayama et al. 2014).

Remarks.

Tetramorium bicarinatum is an alien tramp species found in disturbed areas in warmer regions of the world except in Africa. It belongs to the T. bicarinatum species group ( Bolton 1977) together with T. nipponense in Japan. In the queen this species is most similar to T. nipponense , which inhabits forests, preferring wetter conditions. The possession of 2-3 transverse carinae between the propodeal spines is an important characteristic in distinguishing the two species; in T. nipponense these carinae are lacking or much weaker (at most one distinct carina present). Furthermore, the propodeal spine is straight throughout its length in T. bicarinatum , while it tends to have a slightly up-curved apex in T. nipponense . New queens are attracted to light.

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.