Dr. Murai Éva szerk.: Parasitologia Hungarica 21. (Budapest, 1988)
Parasit hung. 21. 1988 Scope of and proposal for systematics of the Amphistomida (Lühe, 1909) Odening, 1974 (Trematoda) Dr. Ottó SEY Department of Zoology, Janus Pannonius University, Pécs, Hungary "Scope of and proposal for systematics of the Amphistomida (Lühe, 1909) Odening, 1974 (Trematoda)". - Sey., O. - Parasit, hung., 21: 17-30. 1988. ABSTRACT. The taxon Amphistomida contains a monophyletic group of digenetic trematodes, parasitic in all higher vertebrate taxa. The posteriorly located ventral sucker, both in adult and in larval stage, and the epidermal cell formula of the miracidium are the main in-group character states of the taxa. The taxonomic position of the monostome groups of trematodes , assigned to amphistomes by previous authors, is analyzed. The outline of a new scope of amphistomes is formularized and a new classification scheme is proposed. Caballerodiscus gen.n. is described. KEY WORDS: Amphistomida, scope and phyletic relationship, proposed systematics, Caballerodiscus gen. n. The taxon Amphistomida comprises a natural group of digenetic trematodes and has the rank of order in the modern classification of higher taxa of trematodes. Morphologically, their generalized, in-group feature is the postero-terminally spaced ventral sucker. Biologically they are one of the few groups of flukes whose representatives are parasitic in all higher taxa of vertebrate hosts. The scope of amphistomes has considerably varied since the 19the century, when the name Amphistoma was established by RUDOLPHI (1809). It referred to the erroneous observation of they having a mouth-opening at both ends of the body. RUDOLPHI's category, however, embraced also those flukes which, in the present interpretation, belong to another natural taxon, Strigeida. The generic name Amphistomum was set up by NITZSCH (1819), and of RUDOLPHI's species those were allocated to this genus which were characterized by the presence of an oral opening at the anterior body and by ventral sucker posterio-terminally. By the turn of the century it became evident that the species assigned to this genus, Amphistomum , are a heterogeneous assemblage of flukes. In his endeavour to establish the homogeneous structure of this taxon, the genus Amphistomum was divided into various genera ( Paramphistomum , Cladorchis etc.) by FISCHOEDER (1901, 1903), and they were transfered to the family Paramphistomidae: a category created by the same author. Subsequent authors have accepted FISCHOEDER's nomenclature and the suprafamiliar categories, implying that the whole group of amphistomes were constituted from this name (e. g. Paramphistomatoidea Stiles et Goldberger, 1910, Paramphistomata Szidat, 1936; Paramphistomiformes Travassos, Freitas et Kohn, 1963; Brooks et al. 1985). Recently ODENING (1974), with the meanwhile intention of designating the natural higher taxa of trematodes, proposed the usage of the name Amphistomida (Lühe. 1909) for the order, em-
