Dr. Murai Éva szerk.: Parasitologia Hungarica 21. (Budapest, 1988)
canals 0.032-0.038 wide, with anastomoses. Dorsal excretory canals 0.009-0.012 wide. Genital ducts dorsally to excretory canals. Cirrus sac with weakly-developed musculature, crossing excretory ducts about its middle part. Cirrus cylindrical, armed with small spines. Internal seminal vesicle elliptic, in mature proglottides in the proximal 1/3 part of cirrus sac, in postmature proglottides - from half to whole internal volume ot the sac. External seminal vesicle in mature proglottides with small dimensions and seems as cellular aggregation situated close to aporal end of cirrus sac. Testes numerous, situated in aporal half of middle field; in poral direction dorsally overlapping the aporal lobes of ovary; in anterior direction reaching up to tubular stage of uterus but not près ant anteriorly to it; not situated beyond the aporal excretory canals. Female genital organs situated porally. Vitellarium slightly lobed, with two (in some cases not distinct) wings. Ovary highly lobed, when fully developed reaching up to cirrus sac porally and to the middle of proglottis aporally. Mehlis' gland not visible. Seminal receptacle elongate, fully developed in last mature proglottides and first postmature ones (15-22nd proglottis). Vagina short , straight or slightly curved tube, situated ventrally to cirrus sac and opened postero-laterally to male orifice. Uterus beginning its development in premature proglottides, simultaneously with male and female genitalia; in 7-10th proglottides it seems as cord-like cellular aggregation situated in anterior part of proglottis; its ends do not reach laterally to excretory canals. In 10-12th proglottides ends of the aggregation lateral to excretory canals and distinct lumen forming in it. In 13-15th proglottis uterus tubular, gradually extending in anterior and posterior directions. In 16-17th proglottis forming of anterior sacculations begins, in 17-19th - of posterior sacculations. In 21-24th proglottis uterus filling almost whole gravid proglottis; in this stage its walls not well visible. Eggs spherical or slightly oval, with well-developed pyriform apparatus. Remarks: The taxonomy of A. dentata was discussed in detail by RAUSCH (19 76), TENORA and MURAI (1980) and GENOV (1984). In spite of the contradictory opinions of different authors in the past, the validity of A. dentata and its position as a senior synonym of Paranoplocephala brevis Kirschenblat, 19 38 is without any doubt at present. A. dentata is the most widespread species of the genus, parasitizing voles throughout Palaearctic Eurasia. The considerable morphological variability and the range of the hosts suggest that this species is probably composite. A similar presumption was expressed by RAUSCH (1976) who supposed that the Siberian form of P. brevis described by SPASSKY (19 51) is probably an independent species. In the course of the present study, three samples of A. dentata from M._niy_alis and M._subterraneus_ from the high-mountain regions of the Pirin Mts. and from M. _g_uentheri near the Black Sea coast (about 8 m above the sea level) were characterized. According to earlier reports, in Bulgaria A. dentata is distributed in voles only in mountain regions; in other rodents it has been found occasionally in areas where its main hosts _M^_my_alis and M. subterraneus. are numerous (GENOV, 1984). That is why the specimens studied from _M._guentheri may be considered as representatives of a population isolated geographically from those in the high-mountain regions. It is also possible that the samples from M. nivalis and _M._sub-^ tej?raneus_ represent at least partially isolated populations since these two hosts inhabit different although neighbouring biotopes (M._myaTis * a a petricolous species; M. subterraneus inhabits high-mountain meadow communities). When comparing the cestodes collected from the three hosts, no significant qualitative differences were found. Although the ranges of the main metric features overlap (Table 1), some of their means (number of testes, dimensions of cirrus sac and seminal vesicles, length of seminal receptacle) differ significantly (Table 2). The differences in the length of seminal receptacles are a result of their development in proglottides with a different number in the strobila: in specimens from M^jiiyalis the receptacle developes from 11-15th to
