THE FIRST DATA ON MICROTURBELLARIANS (PLATHELMINTHES, RHABDITOPHORA) OF THE BOGUCHANSKY RESERVOIR. 1. KALYPTORHYNCHIA OF BAIKAL ORIGIN, WITH DESCRIPTIONS OF THREE NEW SPECIES

Abstract

This series of reports is devoted to taxonomic investigations of the microturbellarian fauna (Plathelminthes, Rhabditophora) of the Boguchansky reservoir, lower flow of the Angara River, eastern Siberia. The first report provides information about ten species of Kalyptorhynchia (Rhynchokarlingiidae) previously described from Lake Baikal. Three of them are new species, all described in the present paper. The new species of Kalyptorhynchia belong to the genera Mariareuterella Timoshkin Grygier 2005, Riedelella Timoshkin 2004 and Rhynchokarlingia Timoshkin et Mamkaev 2004, respectively. A species with five cuticular hooks in the male copulatory apparatus is discovered for the first time. The diagnosis of the genus Rhynchokarlingia is expanded. All species are found in the lower reaches of Angara River. Rhynchokarlingiidae is a family of kalyptorhynchian worms autochthonous in Baikal. It seems logical to assume that all newly described species are also of Baikal origin. Endemic Baikal Kalyptorhynchia are found for the first time in an area so remote (about 1400 km) from Lake Baikal. Our records significantly expand the distribution area of Rhynchokarlingiidae, with the Boguchanskoye reservoir of Angara River to be considered as the northern range limit of their distribution. Illustrated descriptions of nine species (including three new ones), comparisons with previously described taxa, information on distribution and brief ecological data are also given.