MORPHOMETRY OF BRACHIONUS-PLICATILIS (ROTIFERA, BRACHIONIDAE) FROM THE CASPIAN SEA REGION

Materials were collected in temporary ponds at the Caspian Sea shore ( Mangyshlak peninsula) differing in hydrochemical and trophic condition s. Morphologycally the whole Mangyshlak race differs from the Azov-Bla ck Sea one by the presence of a projection at the hole for the leg at the lorica back side. By the rest of characters the individuals in the majority of rotifers populations belonged to the typical form of Brac hionus plicatilis plicatilis. According to S, L-classification only fo rms from two ponds could be referred to S-type, the rest occurred an i ntermediate position between S and L types. The range of the lorica le ngth in all the investigated B. plicatilis populations was 164-353 mic rons, that of width being 123-254 microns. These estimates permit us t o refer the Mangyshlak race to a relatively large variety of this spec ies. After prolonged keeping in laboratory the lorica dimensions in th e Mangyshlak race rotifers practically did not differ from those in na ture.