Lasius hayashi 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

4.4.56 Lasius hayashi Yamauchi & Hayashida 1970

Lasius hayashi Yamauchi & Hayashida 1970

[type investigation]

Type material: one paratype worker from the holotype nest series labelled ” Sapporo Hokkaido 27-VII-1967 K. Yamauchi“; depository SMN Görlitz.

All material examined. A total of 6 nest samples with 29 workers were subject to NUMOBAT investigation. These originated from Japan. For details see supplementary information SI1.

Geographic range. Japan from 32°N to 45°N, Korea and Kuriles. The upper altitudinal limits are 600 m at 44°N in Hokkaido and 1600 m at 34°N in Shikoku.

Biology (according to Yamauchi 1979, Yamauchi, Ito & Suzuki 1986). Main habitat is shady deciduous woodland with large trees. The nests are mostly constructed within the root systems or in hollow trunks of trees and sometimes in rotten logs and may contain carton structures. Being active in Sapporo to mid November, L. hayashi has a longer foraging season than sympatric congeneric species. The foraging paths are almost completely covered by macerated plant and humus material both on tree trunks and on the ground near the tree where trophobiotic Homoptera are tended. Flights were observed from early July to late August and start in the late evening at light intensities of only 0–10 lux and air temperatures of 22– 24°C. Air movements and rain stop the flight.

Diagnosis ( Tab. 11 , Figs. 107 –108; key; image in www. antWeb.org with specimen identifier CASENT1041269):

Large (CS 994 µm). Head shorter than in other sympatric species (CL/CW 900 1.049) and usually with concave posterior margin. Scape rather short (SL/CS 900 0.978). Postocular distance medium and eye rather small (PoOc/ CL 900 0.241, EYE/CS 900 0.230). Torulo-clypeal distance rather large (dClAn 900 5.07). Number of mandibular dents rather low (MaDe 7.95). Terminal segment of maxillary palp rather long (MP6/CS 900 0.194). Pubescence on clypeus moderately dense (sqPDCL 900 4.59); on frons rather short (PLF 900 28.4); on scape subdecumbent to suberect and difficult to distinguish from shorter setae; on hind tibia decumbent to appressed, contrasting the situation in the long, suberect to erect setae. Gular and pronotal setae long (GuHL/CS 900 0.114, PnHL/CS 900 0.154). Whole body covered by numerous standing setae (nOcc 900 13.1, nGen 900 5.1, nGu 900 6.4, nSc 900 18.3, nHT 900 17.4,nSt 900 4.9). Coloration: mesosoma, petiole, scape, femora and tibiae pale yellowish brown, head darker yellowish brown, gaster blackish brown or dark brown with yellowish tinge.

Comments: Lasius hayashi is separable from the sympatric similarly hirsute L. japonicus by the broader head, shorter scape, more convex petiole sides and the homogenously yellowish brown head capsule.

Figures

Figs. 107 and 108: Lasius hayashi; paratype