Lasius sakagamii Yamauchi & Hayashida 1970

Seifert, Bernhard, 2020, A taxonomic revision of the Palaearctic members of the subgenus Lasius s. str. (Hymenoptera, Formicidae), Soil Organisms 92 (1), pp. 15-86 : 79-80

4.4.57 Lasius sakagamii Yamauchi & Hayashida 1970

Lasius sakagamii Yamauchi & Hayashida 1970

[type investigation]

Type material: one paratype worker from the holotype nest series labelled ” Sapporo Hokkaido 30-VII-1966 K. Yamauchi“; depository SMN Görlitz.

All material examined. A total of6 nest samples with 19 workers were subject to NUMOBAT investigation. These originated from Japan. For details see supplementary information SI1.

Geographic range. Widely spread all over Japan from 33°N to 45°N from sea level to 500 m.

Biology (according to Yamauchi 1979, Yamauchi, Ito & Suzuki 1986). Main habitat are sun-exposed deposition areas of alluvial and aeolian sands with only sparse vegetation; these are river banks, dry river beds, sand dunes or road sides. Nests are usually constructed at spots with bare sand or under stones and have numerous distinct chambers usually reaching down to 60 cm. Nuptial flights were observed from early July to late September at warm evenings with air temperatures> 22°, high air humidity and no air movements. The species is polygynous and in many nests only males fly. Nuptial flight of gynes only takes place from nests without males, otherwise they mate intranidally with subsequent dispersal flight. It may form supercolonies dominating large habitat areas.

Diagnosis ( Tab. 11 , Figs. 109 –110; key; images in www. antWeb.org with specimen identifiers CASENT0906279, CASENT1041276):

Medium-sized (CS 887 µm). Head moderately long (CL/CW 900 1.071). Scape long (SL/CS 900 1.034). Postocular distance small and eye medium-sized (PoOc/ CL 900 0.225, EYE/CS 900 0.244). Torulo-clypeal distance large (dClAn 900 5.21). Number of mandibular dents large (MaDe 8.52). Terminal segment of maxillary palp rather long (MP6/CS 900 0.194). Pubescence on clypeus dense (sqPDCL 900 3.78) and on frons rather long (PLF 900 33.0). Gular and pronotal setae rather long (GuHL/CS 900 0.110, PnHL/CS 900 0.157). Whole body covered by extremely numerous standing setae (nOcc 900 23.4, nGen 900 16.1, nGu 900 18.6, nSc 900 32.0, nHT 900 29.8, nSt 900 12.6). Mesosoma with very flat propodeal dome and convex to angulate-convex posterior propodeal slope that is transversally carinulate. Petiole scale in lateral view thick, low and with a blunt apex; in anterior view rather narrow, with convex to nearly straight subparallel sides. Coloration: mesosoma medium brown with a yellowish-reddish tinge, head a little and gaster distinctly darker; sometimes whole body concolorous pale or dark brown.

Comments: Lasius sakagamii represents an unmistakable combination of extremely large setae numbers, flat propodeal dome, low petiole and low clypeal pubescence distance.

Figures

Figs. 109 and 110: Lasius sakagamii; paratype