Dr. Kassai Tibor - Dr. Murai Éva szerk.: Parasitologia Hungarica 8. (Budapest, 1975)

Zygocotyle lunata (Diesing, 1836) (Figs. 25-27) This species can be found in birds and mammals in North and South America. The histology of the muscular organs has not been examined so far. The pharynx is 450-465 u in length and 325-332 u in breadth. Exterior longitudinal layer well developed, interior longitudinal one comprises some coarse muscle fibres (Fig. 25). Of the circular muscles the, exterior layer extends over the first third of the pharynx, strongly developed. Middle layer is slightly developed and hardly observable, extending to the first three-quartes of the pharynx. Interior layer poorly developed and it is seen in the first half of the pharynx. Number of the radial muscle fibres is about 18-20, they are coarse with ramifications outwards (Fig. 25). Primary pharyngeal sacs present protruded dorso-laterally from the posterior part of the pharynx (Fig. 25). Pharynx of this species resembles to the Microrchis type (NÄSMARK, 1937). The genital atrium is small, about 250-270 yu in diameter with weakly developed musculature. Pars prostatica is fairly small (about 150 ju) surrounded by a few prostatic gland cells. There is a minute genital papilla, there are neither sphincter papillae nor genital sphincter (Fig. 26). Pars musculosa is a short, thin walled tube, forming some convolutions. The acetabulum opens ventrally, its diameter is about 1400-1500 u. Radial muscle fibres are densely packed (Fig. 27). In specimens available for investigation dorsal and ventral muscle series were detectable, number oi units in series were as follows: d. e, : 43-56; d.i.: 26-30; v. e. : 11-15; v. i. : 34-42, Muscle units in the d. e. series are stronger. The pores of the excretory duct and of the Laurer's canal are situated 2000-2050u, and 2150-2200 u, respectively, from the posterior end of the body. It can be concluded, that the histological structure of the muscular organs of species described for the first time in this paper fits well the major groups set up by NÄSMARK in his monograph. Inside the individual groups, however, differences were also seen in structure of the organs as compared to that of the hitherto described types. E. g. the pharynx of Z. lunata 'resembles the Microrchis type but exibits also different features, such as absence of the anterior sphincter and presence of a strongly developed exterior circular muscle layer. New types of the genital atrium were recognized in species G. aegyptiacus and C. fabaceus. The arrangement and number of the muscle units in the acetabulum of G. hominis show certain deviations too from what had been written in the literature. On the basis of these observations the possibility is raised to designate new types of some of the muscular organs. For this, however, further work is needed. Acknowledgements The author is inbedded to Mr. D. J. FORRESTER (Univ. of Florida, USA) and Mr. V. V. ROMASCHOV (Voronesh, USSR) for supplying amphistomes for the present study. Fig. 19: Dorsal half of acetabulum of Gastrodiscoides hominis; Figs. 20-24: Median sagittal sections of Stichorchis subtriquetrus - 20-21 = Anterior and posterior parts of pharynx; 22 = Genital atrium; 23-24 = Dorsal and ventral halves of acetabulum; Figs. 25-27: Median sagittal sections of Zygocotyle lunata - 25 = Pharynx with primary pharyngeal sacs; 26 = Genital atrium; 27 = Dorsal half of acetabulum.