Acta Parasitologica, Vol. 51, No. 3, 2006, 176-181 Reda M. El-S. Hassanine - Trematodes from Red Sea fishes: Pachycreadium lethrini sp. nov. (Opecoelidae Ozaki, 1925) and Pseudometadena aegyptensis sp. nov. (Cryptogonimidae Ward, 1917), with a review of their genera
Department of Sciences and Mathematics, New Valley-Faculty of Education, Assiut University, El-Kharga, New Valley, Egypt
Corresponding address: Redaaa2003@yahoo.com
ABSTRACT
Specimens of the fishes Lethrinus nebulosus Forsskal (Lethrinidae) and Diplodus noct Valenciennes (Sparidae) were caught
in the Red Sea off the coast of Sharm El-Sheikh, South Sinai, Egypt. Ten (33%) and 12 (24%) of these fishes, respectively,
were found to harbour intestinal trematodes. L. nebulosus was parasitised by Pachycreadium lethrini sp. nov. (Opecoelidae) and
D. noct by Pseudometadena aegyptensis sp. nov. (Cryptogonimidae). P. lethrini sp. nov. is unique in having distinctly unequal
testes, contiguous gonads arranged obliquely in the right side of hindbody and a small egg size. However, it differs from each
of the other three species of the genus in several other features: from P. gastrocotylum (Manter, 1940) Manter, 1954 in having
a smaller sucker ratio and vitelline follicles terminating anteriorly at the level of intestinal bifurcation; from P. carnosum
(Rudolphi, 1819) Cortini et Ferretti, 1959 in having a smaller body, a smaller sucker ratio, a genital pore situated ventrally to
the anterior border of pharynx, a pretesticular ovary and vitelline follicles extending anteriorly to the level of intestinal bifurcation;
and from P. lerneri Sogandares-Bernal, 1959 in having a larger body, a smaller sucker ratio and an unlobed ovary.
P. angolensis Aleshkina et Gaevskaya, 1985 is considered an invalid species in Pachycreadium. P. aegyptensis sp. nov. is similar
to P. celebesensis Yamaguti, 1952, but mainly differs in having a larger pharynx, a much shorter oesophagus, extensive
vitelline acini and a shorter seminal vesicle. Pachycreadium Manter, 1954 and Pseudometadena Yamaguti, 1952 are briefly
reviewed.
KEY WORDS: Digenea, Opecoelidae, Pachycreadium lethrini sp. nov., Cryptogonimidae, Pseudometadena aegyptensis sp. nov., fishes, Red Sea