Studies on the Aquatic Oligochaete Fauna in Lake Biwa, Central Japan I. Checklist with Taxonomic Remarks.

On the basis of newly collected specimens, 35 taxa of aquatic Oligochaeta are listed from Lake Biwa, central Japan, with synonymy lists and some taxonomic remarks. The list covers all the species previously recorded from the lake, and is composed of one lumbriculid, 19 naidids, 14 tubificids and one biwadrilid. Among them, Vejdovskyella (V.) simplex, Teneridrilus mastix and Aulodrilus limnobius are new to Japan. In addition to them, Uncinais uncinata, Specaria josinae, Ophidonais serpentina, Branchiodrilus hortensis and Aulodrilus japonicus are newly recorded from Lake Biwa. The present list covers 58% of Japanese oligochaete species so far reported. An infraspecific variant form of Branchiura sowerbyi which is devoid of gill filaments and was previously regarded as a dependent species, Kawamuria japonica, is endemic to Lake Biwa. Recently redescribed Embolocephalus yamaguchii is also potentially endemic to the lake. Lake Biwa is characterized by having Branchiura sowerbyi even at the deep and cold profundal.