Chironomus suwai, a New Species of the plumosus Group (Diptera, Chironomidae) from Japan

Abstract

Cytological examination of the larvae of the species previously referred to as Chironomus plumosus in Japan, reveals that it is actually a new member of the plumosus group. This species is described as C. suwai on the basis of the karyotype, since this is the most reliable method for recognizing the species. It belongs to the thummi cytocomplex, and is polymorphic in chromosome arms A, B and E. A B-chromosome was present in one of the two populations (Tsukuba) studied. The banding pattern of the polytene chromosomes indicates that C. suwai is most closely related to C. borokensis, from which it differs by the smaller centromeric bands, and the presence of three unique inversion polymorphisms. The difference in centromeric size is an important indicator that these are separate species, since such differences are common between species of Chironomus. Some notes are included on the larvae, particularly in relation to their use in lake typology, and the later life history stages.