Lasius japonicus Santschi 1941

4.4.27 Lasius japonicus Santschi 1941

Lasius emarginatus var. japonicus Santschi 1941

[type investigation]

Type material: Lectotype worker plus 4 paralectotype workers labelled “ Japan. Tokiawa Hokkaido Teranishi“, ” lectotype outer worker desig. by E.O.Wilson “; depository NHM Basel.

All material examined. A total of 32 nest samples with 104 workers were subject to NUMOBAT investigation. These originated from China (8 samples), Japan (19), Korea (1) and Russian Far East (4). For details see supplementary information SI1.

Geographic range. NE China, Korea, Russian Far East, Japan. Extreme points of the known range are marked by Beijing (40.00°N, 116.34°E), Nukabira (43.36°N, 143.19°E), Kyushu (32.5°N, 130.9°E) and Khabarovsk (48.49°N, 135.11°E). The upper altitudinal limit seems to be at 1700 m on Mount Paekdusan (41.91°N, 128.10°E) and 2100 m in Honshu at 36°N.

Diagnosis (Tab. 6, Figs. 53 –54; key; images in www. antWeb.org with specimen identifiers CASENT0217772, CASENT0280450, CASENT0912291):

Medium-sized (CS 950 µm). Scape and maxillary palp length indices and torulo-clypeal distance large (SL/CS 900 1.012, MP6/CS 900 0.205, dClAn/CS 900 5.50). Postocular distance and eye size medium (PoOc/CL 900 0.240, EYE/CS 900 0.244). Number of mandibular dents medium (MaDe 900 8.11). Pubescence on clypeus moderately dense (sqPDCL 900 4.33). All body parts with rather numerous and rather long standing setae (PnHL/CS 900 0.150, GuHL/CS 900 0.116). Coloration: polymorphous. The light morph with pale yellowish-reddish brown mesosoma, head and gaster with same tinge but darker; mandibles and anterior clypeal border (sometimes whole clypeus) yellowish to bright orange. Dark morph with dark to blackish brown head, mesosoma, gaster, coxae, femora and tibiae; tarsae, scape, mandibles and anterior clypeal border paler yellowish brown.

Biology. Very eurypotent species, occupying the ecological niche of Lasius niger. It inhabits all kinds of natural to anthropogenous, open to semi-shaded habitats, avoids very shady woodland and constructs the nests in most different substrates. According to Yamauchi (1978) the nests do not show conspicuous mounds of mineralic soil material as it is typical for Lasius niger. Nuptial flight takes place in early morning (Yamauchi et al. 1986).

Comments. Lasius japonicus is separable from all related species by exploratory and hypothesis-driven data analyses with error rates <1%. For separation from the most similar sister species L. chinensis sp. nov. see there.