A DESCRIPTION OF SPERMATOZOAN ULTRASTRUCTURE AND SOME ANATOMICAL CHARACTERS IN BRANCHIOBDELLA-KOZAROVI SUBCHEV, 1978 (ANNELIDA, CLITELLATA), AND REVIEW OF THE SPERMATOZOAN MORPHOLOGY WITHIN THE GENUS

The use of spermatozoan ultrastructural morphology to produce a meanin gful phylogeny requires a critical number of descriptions from represe ntative species in a taxon. Branchiobdella spermatozoan morphology is considered to be aberrant within the Clitellata. The description of th e spermatozoon of B. kozarovi has extended the information on interspe cific variation in this genus. The spermatozoa of this species have an acrosome (16 mum long), nucleus (4.5 mum long), midpiece (1.5 mum lon g), and tail (158 mum long), with a total length of about 180 mum. The acrosome is a thick helix with about 15 gyres, contains an acrosome t ube and acrosome vesicle which has branches penetrating into the centr al subacrosomal space. The acrosomal ''button'' is located on the ante rior surface, with the ''cork'' and secondary tube at the posterior. T he rod-shaped nucleus has a concavity in both the anterior and posteri or surfaces. The midpiece has seven, parallel mitochondria twisted abo ut the central axis. The centriolar remnant with an indistinct ninefol d symmetry in cross section is located posterior to the mitochondria. The prominent central sheath extends from the mitochondria to the end of the flagellum, which has no end piece. The axoneme has glycogen gra nules located along its length, and an helical marginal fiber. A revie w of descriptions of spermatozoa of Branchiobdella shows some inconsis tencies. The observations of two anterior nephridial pores and an ever sible penis completes the anatomical characters of B. kozarovi used in current branchiobdellidan taxonomy.