Tetramorium smithi Mayr, 1879

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 smithi Mayr, 1879

Figs 1d , 3a , 4g , 6a

Queen diagnosis.

Measurements (n = 2): TBL 3.4/3.1, HL 0.73/0.74, HW 0.70/0.71, SL 0.43/0.43, EL 0.21/0.19, EW 0.17/0.17, PtW o.29/0.27, PpW 0.42/0.38, CI 95.9/95.9, SI 61.4/60.6, ELI 28.8/25.7. Head, mesosoma and waist brown to reddish-brown, with dorsum of head, antenna and legs dark brown; gaster black. Dorsum of head longitudinally rugose; other portions of head puncto-reticulate. Frontal carina strong, defining dorsal margin of antennal scrobe; antennal scrobe superficially sculptured and shiny. Clypeus with three longitudinal carinae, with anterior margin entire. Mandible superficially sculptured and shiny. Antenna with 11 segments. With mesosoma in dorsal view, pronotum sparsely transversely rugose; mesonotum and propodeal dorsum densely with longitudinal parallel rugae; propodeal declivity partly smooth, shiny; transverse carinae absent between propodeal spines; in profile view, pronotum, metapleuron and lateral face of propodeum rugose or irregularly sculptured; mesopleuron, especially on lower portion, with weaker sculpture and somewhat shiny. Petiole and postpetiole with smooth portions on their dorsum; petiolar peduncle and sternite smooth and shiny; lateral face of petiolar node and lateral and ventral faces of postpetiole sculptured; petiole ventrally with sharp longitudinal ridge throughout; postpetiole more than 1.4 times as broad as petiole in dorsal view. Gastral tergite 1 entirely smooth and shiny. Hairs on antennal scape and mid- and hind-tibiae decumbent to appressed; those on tibiae slightly approaching suberect.

Caste difference.

Worker measurements (n = 5): TBL 2.1-2.3 (2.2), HL 0.64-0.68 (0.65), HW 0.56-0.60 (0.59), SL 0.38-0.41 (0.40), EL 0.15-0.17 (0.16), EW 0.10-0.12 (0.11), PtW 0.19-0.23 (0.21), PptW 0.28-0.30 (0.29), CI 87.5-93.8 (90.5), SI 64.4-69.5 (67.4), ELI 23.4-25.0 (24.0). Worker much smaller than the queen. Eye smaller, distance between anterior eye margin and mandibular base as long as or slightly longer than major diameter of eye; in the queen the distance much shorter than major diameter of eye. Eye anteriorly distinctly tapered; in the queen eye anteriorly broadly rounded. Pronotal dorsum rugose except for small area around anterolateral corner reticulate; in the queen pronotal dorsum coarsely reticulate. Mesonotum longitudinally rugose in both castes. Mesopleuron entirely coarsely sculptured; in the queen, sculpture weaker, especially in lower portion.

Specimens examined.

S. Ryukyus: 1q (winged), Miyako-jima, 30.x.2019, nest in soil, on forest pass, F. Ito leg. (FI19-209); 1q (winged), Hirarahigashi, Miyako-jima, emerged on 28.vii. 2020 in colony (FI19-203) collected on 29.x.2019 and kept in lab., F. Ito leg. (Figs 3a , 4g , 6a )

Distribution in Japan.

Nansei Islands. The northern limit lies in Okinawa-jima (Central Ryukyu Islands) ( Terayama et al. 2014).

Remarks.

Tetramorium smithi belongs to the T. angulinode species group, in which the antenna has only eleven segments in the female castes ( Bolton 1977). This species is easily separated from other Japanese congeners by the reduced antennal segments (11), shiny mandible (shared by T. pacificum ) and black gaster (shared by T. tsushimae ). This is the only Japanese Tetramorium species with the mesonotum entirely regularly rugose in both female castes.

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 3. Japanese Tetramorium queens: habitus in profile a T. smithi (Hirarahigashi, Miyako-jima, Okinawa-ken) b T. tanakai (Mandabaru, Yonaguni-jima, Okinawa-ken) c T. tsushimae (Nokono-shima, Fukuoka-shi). (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 6. Japanese Tetramorium queens: habitus in dorsal view a T. smithi b T. tanakai c T. tsushimae.