Three diplectanid monogeneans from marine finfish (Epinephelus spp.) in the Far East

Two new species of diplectanid monogeneans, Diplectanum grouperi and Pseudo rhabdosynochus coioidesis from the marine finfish Epinephelus coioides and E. aerolatus (Serranidae), cultured in floating cages in Malaysia, Indonesi a and Hong Kong, were described and compared with P. lantauensis Beverley-B urton and Suriano, 1981 from the same hosts. There is no other close specie s sharing the features of Diplectanum grouperi. The possession of a copulat ory organ with an open cup-like proximal part and a narrow tubular distal p art is a main distinguished feature of D. grouperi. Pseudorhabdosynochus co ioides is most closely related to P. epinepheli Yamaguti, 1938, but can be distinguished from it by the shape and the size of the haptor, hamuli, copu latory organ, the lack of a muscular bulbus ejaculatorius, a greater number of rows in the squamodiscs and the location of the testis. Pseudorhabdosyn ochus lantauensis from the present hosts differs from that described from t he original hosts, Epinephelus brunneus and E. fario in the shape of the do rsal bar and vagina.