Lasius chinensis, Seifert, 2020

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 : 64-65

4.4.28 Lasius chinensis sp. nov.

Etymology: The name refers to the terra typica China.

Type material: Holotype labelled ”CHI: 36.0489°N, 103.8566°E Lanshou , 1522 m Universitätspark Seifert 2011.08.07 -87“; 2 paratype workers from the holotype nest sample on another pin, 3 paratype workers from the same sample in ethanol; depository SMN Görlitz.

All material examined. A total of 13 nest samples with 41 workers, all originating from China, were subject to NUMOBAT investigation. For details see supplementary information SI1.

Geographic range. Only NE China; from E Qinghai (36.6°N, 101.7°E) east to Shangdon (36.4°N, 117.4°N), The most southern and northern known sites are Chengdu (30.64°N, 104.05°E) and Yong Deng (36.7°N, 103.3°E). The altitudinal distribution ranges from 370 in Shaanxi to 3500 m in E Tibet.

Diagnosis ( Tab. 6 , Figs. 55 –56; key):

Medium-sized (CS 965 µm). Scape and maxillary palp length indices and torulo-clypeal distance large (SL/CS 900 1.017, MP6/CS 900 0.199, dClAn/CS 900 5.63). Postocular distance and eye size medium (PoOc/CL 900 0.237, EYE/ CS 900 0.240). Number of mandibular dents medium (MaDe 900 8.33). Pubescence on clypeus moderately dense (sqPDCL 900 4.14). All body parts with very numerous and long standing setae (nOcc 900 21.6, nGu 900 17.0, nSc 900 26.2, PnHL/CS 900 0.159, GuHL/CS 900 0.121). Coloration: dark to blackish brown; antennal funiculus, tibio-femoral joint regions, tarsae and metatarsae, and anterior clypeal border paler with a yellowish tinge.

Biology. It was found at river banks, in open forest and in parks. It regularly occurs in concrete-sealed city centers provided there are few trees or some greenery. It is obviously a eurypotent species with a niche comparable to Lasius niger .

Comments. Lasius chinensis sp. nov. is a western parapatric sibling species of L. japonicus . The contact zone of both species seems to be between 116 and 117° E, from about Beijing south to Shangdong, with syntopic occurrence of both species observed in one locality. The sister-species relation to L. japonicus is indicated by highly similar shape characters. The morphological separation from the latter is mainly given by the more profuse pilosity. Running exploratory data analyses with samples in which data of all standard characters were available, 13 nest samples with 41 workers in L. chinensis sp. nov. and 21 nest samples with 59 workers in L. japonicus , resulted in 0% classification error in NC-NMDS.kmeans clustering but in errors between 2.9 and 8.8% in the other algorithms of NC-clustering. In order to avoid overfitting of the controlling discriminant functions, the number of considered characters was reduced to seven: CL/CW 900, EYE/CS 900, sqPDCL 900, nGu 900, nSc 900, nHT 900, and nSt 900. With these input data, NC-Ward, NC-part.kmeans, NC-part.hclust and NC-NMDS.kmeans achieved a fully congruent clustering with an error of 0% on the nest sample level when checked by the controlling discriminant function. On the individual level, the LOOCV-LDA misclassified 2% of 100 workers.

Figures

Figs. 55 and 56: Lasius chinensis sp. nov.; holotype