Dr. Murai Éva szerk.: Parasitologia Hungarica 21. (Budapest, 1988)

bracing amphistomes of all kinds. ODENING (1963, 1974) pointed out that it would be reasonable to retain the name of the suprafamiliar category even if the rank of the original group was altered by subsequent taxonomic rearrangements. Moreover, as the taxon Amphistomida is 'nowadays considered a natural taxon as it was in LÜHE's time and was :it nominated by him, as the first suprafamiliar category, and finally as there is no nomenclatural regulation to apply one of the valid generic names to nominate higher taxon, the present writer agrees with ODENING's notion on the priority of the taxonomic name Amphistomida (Lühe, 1909) Odening, 1974. (Amphistomida was formed of LÜHE's Amphistomata with the aid of the -ida, added to the root of the word.) Since the beginning of this century the scope of the amphistomes has been considerably enlarged not only by the discovery of newer.forms but also by the allocation of groups of flukes of debated taxonomic position to the amphistomes. The family Microscaphidiidae was assigned to the amphistomes by ODHNER (1911); Opistholebetidae and Opisthoporidae by FURTH (1929); Gyliauchenidae by OZAKI (1937); Cephaloporidae by TRAVASSOS (1934); Mesometridae and Notocotylidae by SZIDAT (1939); Metacetabulidae by SKRJABIN (1949); Heronimidae by CRANDALL (1960); and Zonocotylidae by YAMAGUTI (1963) and PADI LH A (1978). ODHNER (1911) was of the opinion that the m onostqme microscaphidiid trematodes had been amphistomes but they lost their ventral sucker, and their organological resemblances (pharyngeal appendages, lymphatic system etc.) make them similar to amphistomes. GROSCHAFT (1977) clarified that the pharyngeal appendages are glandular in nature in microscaphidiids and thus they are not homologous with those of amphistomes. Since that time it has been pointed out that the lymphatic system of is present not only in the taxa in question but also in several others being phylogenetically distant (SEY, 19 77). CABLE (1956), studying the development of Opistholebes diodontis in the final host, came to the conclusion that the amphistome plan of the taxa Opistholebetidae and probably the Gyliauchenidae and Cephaloporidae should be considered secondary in ontogeny and in phylogeny alike. STUNKARD (1930) re-examined MacCALLUM's species Paramphistomum aspidonectes

, for which FUKUI (1929) set up the genus Opisthoporus and the family Opisthoporidae respectively, and stated that it should be transferred to the family of Pronocephalidae. ODENING (1961, 1974) emphasized that the taxa Notocotylidae and Mesometridae assigned by SZIDAT (1939) to amphistomes is not acceptable due to their monostome structure, both in adult and in developmental stages (Notocotylidae). In the taxon Metacetabulidae it was recently elucidated by BILQEES (1974) that the rudimentary ventral sucker, which was the basis of putting this taxon to the amphistomes (SKRJABIN, 1949), is in fact not a sucker at all but a secondary excretory bladder. Beside the above-mentioned families, the species Khalilloossia ali-ibrahimi Hilmy, 1949 (Cephaloporidae), Choanomyzus tasmaniae Manter et Crowcroft, 19 50 (Opistholebetidae); Podocnemitrema papillosus Alho et Vincente, 1964 (Microscaphidiidae) have also been allocated to the amphistomes. Now these species belong to the families indicated in brackets, whose taxonomic position and non-amphistome nature were discussed above. At the same time it has been convincingly demonstrated (CABLE, 1956) that the monostome taxon Heronimidae (shared traits with amphistomes are epidermal cell formula of miracidia and position of ventral sucker of the cercariae) and Zonocotylidae (PADILHA, 1978) (shared features with amphistomes are the epidermal structure of miracidia) should be considered as amphistomes. From the above presented controversial views on the scope of amphistomes and from the modern demand that the outline of groups of flukes should be based on the totality of characters, it seems to be obvious that the scope of amphistomes can be formulated by their holo-