Dr. Murai Éva szerk.: Parasitologia Hungarica 16. (Budapest, 1983)
RESULTS AND DISCUSSION HISTO-MORPHOLOGY OF THE MUSCULAR ORGANS Histomorphology of the muscular organs, which is generally applied in amphistome diagnosis of higher vertebrates, seems also to be a useful means for that of lower vertebrates. Unfortunately, there are only a few species of diplodiscids studied in this respect. NASMARK (1937) has examined the structure of the pharynx and acetabulum of Opisthodiscus diplodis- coides only and they were named as Microorchis- and Diplodiscus-types respectively. In species available for examination five types of pharynxes were observed: Ferrum-equinum (holds for Opisthodiscus diplodiscoides ) , Megalodiscus (hold for Megalodiscus americanus, Diplodiscus fischthalicus , D. mehrai ), Megacotyle ( Megalodiscus temperatus , Progonimo discus doyeri ) , Subclavatus (hold for Dermatemytrema trifoliata , Diplodiscus subclavatus) , Pseudodiplodiscus (holds for Pseudodiplodiscus cornu). The Microchis-type of pharynx was held by NASMARK (1937) for species of several genera. Comparative examinations of a great number of amphistomes revealed the heterogeneity of this tpye. Some new types of pharynxes of species as included in the present paper are characterized briefly below; the rest of them will be published in a separate paper. Ferrum-equinum (Fig. 1) There is a pre-sphincteric space in the pharynx with small, loosely packed circular muscle units. Megalodiscus (Figs 2-3) There is no pre-sphincteric space, anterior sphincter and the middle circular layer consist of loosely packed units. Megacotyle (Fig. 4) There is a pre-sphincteric space without circular musculature. The middle circular layer is moderately developed. Subclavatus (Figs 5-6) Pre-sphincteric space without circular musculature. There is no middle circular layer. Pseudodiplodiscus It differs from the preceeding types in having the primary pharyngeal sacs embedded in the wall of the pharynx. The structure of the genital opening was revealed for the first time by our examinations. In general it can be said that the genital opening is small, with a poorly developed musculature; there is only genital papilla without muscle elements. Two new types could be distinguished in the species examined: Spinolosum (hold for M. americanus and D. trifoliata, O. diplodiscoides , D. mehrai ) and Scleroporum (holds for D. sub clavatus ) . Spinolosum (Figs 7-8) Length of the cirrus pouch is about the same as the diameter of the genital opening. Scleroporum (Fig. 9) Length of the cirrus pouch is about 2-3 times longer than that of the diameter of the genital opening.
