Dr. Kassai Tibor - Dr. Murai Éva szerk.: Parasitologia Hungarica 9. (Budapest, 1976)
experiments of alike nature have not yet been done in connection with Paramphistomids we may well suppose that the intermediate host specificity is determined by similar factors in case of Paramphistomids, too. The analysis of the intermediate host spectrum of Paramphistomids suggests that the specificity to such hosts can vary with the species of parasites themselves. E, g, Paramphistomum sukari Dinnik, 1954 develops only in the Planorbid species Biomphalaria pfeifferi (DINNIK and DINNIK, 1957), while the intermediate hosts of P. ichikawai Fukui, 1922, occurring in Japan, the USSR, Europe and Australia, are Helicorbis sujfunensis as well as Gyraulus filialis in the USSR (KISILEV, 1967), Planorbis planorbis in Hungary (unpubHshed data) and Segnitilia alphena in Australia (DURIE, 1953), all being Planorbid snails. Until now no species of Paramphistomids have been found to develop in intermediate hosts belonging to two or more different families, therefore the specificity of Paramphistomids to the species of their adequate intermediate hosts seems to be a quite constant feature. In searching for the intermediate host of P. daubneyi, DINNIK (1962), tried to infect several species of Bulinid, Lymnaeid, Physid and Planorbid snails, but others than Lymnaea truncatula did not pick up the miracidia of P. daubneyi. At the same time he found that infections of L. truncatula with miracidia of P. microbothrium , whose intermediate hosts are Bulinid snails, were unsuccessful. Infestations performed in this laboratory (Hungary) with Planorbis planorbis were also unsuccessful in spite of the fact that Planorbid snails are phylogenetically more closely related to Bulinids than to Lymnaeids. In other words P. daubneyi shows strict specificity to its intermediate host, L. truncatula. It seems fairly certain that the geographical distribution of P. microbothrium corresponds to that of its Bulinid intermediate hosts (B, tropicus and B, truncatus). As Bulinids are not indigenous in Bulgaria, they occur solely in some South-West European countries (the Spanish Peninsula, Sardinia, Corsuca; HAAS, 1935), the species formerly described in Bulgaria as P. microbothrium {ME RE MINSKlí and VISHNYAKOV, 1969; VASSILEV and SAMNALIEV, 1974; MIHAILOVA et al. 1974) is probably a misjudged; P^_daubney_i. As a result of examinations of naturaUy infected snails carried out by KOSAROFF and MIHAILOVA (1959) and POPOV et al. (1967) three species of Lymnaeid snails (L. peregra, L. truncatula, L. turricula) harboured Cercaria pigmentata, a type of Paramphistomid cercariae. Taking the above short analysis of the specificity into consideration KOSAROFF and MIHAILOVA's (1959) and POPOV et al.'s (1967) results are in accordance with our argumentation. P. clavula Näsmark (1937) is the other species of the Bulgarian fauna (MIHAILOVA et. aï! 1974), which shows similarity to P. daubneyi . It has a Clavula type of genital atrium resembling in structure to the Microbothrium type. The genital sphincter of P. clavula , however, is enormously developed and it is about three to four times larger than that of P. daubneyi (Figs. 11-13 were taken with the same magnification, demonstraiting the different sizes of sphincter papillae and genital'sphincter of P. daubneyi , P. microbothrium and P. clavula) . The intermediate host of P. clavula is Bulinus abessynicus (SOBRERO, 1962) and the specificity discussed in connection with P. microbothrium is most likely related to this species as well. Among the Paramphistomid material from cattle in Kavarna most specimens showed a strongly protruded and therefore smaller genital opening which is worth mentioning, because such a form occurs scarcely in both P. daubneyi or P. microbothrium. The structure and measurements of other organs, however, fell within the limits given by DINNIK (1962) and SEY (1974) for P. daubneyi . This appearance (Fig. 10) is very probably allied with a longer prefixative treatment in water, because such protruded génital opening was seen occasionally in specimens of other Bulgarian samples, too (Figs. 8 and 9). This assumption is supported by the fact, that the parenchymal cells were empty and the pharynx was also protruded (Fig. 2) owing to endosmosis. As of this sample only a limited number of specimens were available and prefixation circumstances were unknown, specimens of this type were considered as a variation of P. daubneyi.
