Trypanorhynch cestodes from Indonesian coastal waters (East Indian Ocean)

Results of a study on trypanorhynch cestodes of fishes from Indonesian coas tal waters are presented. A new species, Dasyrhynchus thomasi sp. n., is de scribed, and five species are recorded which all represent new locality rec ords: Tentacullaria coryphaenae Bose, 1797; Nybelinia africana Dollfus, 196 0; Nybelinia scoliodoni (Vijayalakshmi, Vijayalakshmi et Gangadharam, 1996) ; Sphyriocephalus dollfusi Bussieras et Aldrin, 1968; and Otobothrium penet rans Linton, 1907. Their known ranges of distribution are extended to the E ast-Indian Ocean. Scanning and transmission electron microscopy was used to clarify details of the tentacular armature and surface morphology of T. co ryphaenae, D. thomasi and O. penetrans. In T. coryphaenae, hook-like microt riches along the bothridial tegument are embedded in the distal cytoplasm, sometimes showing a split base. The solid tentacular hooks are embedded int o a fibrillar, highly ordered tentacular wall. D. thomasi is distinguished by its characteristically shaped bothridia and a triple chainette with wing ed hooks on the external surface of the tentacle. Tufts of microtriches wit h ciliated sensory receptors are regularly arranged on the bothridial surfa ce of O. penetrans. They show similarities to sensory receptors reported fr om other trypanorhynch cestodes. Otobothrium pephrikos Dollfus, 1969 is con sidered a junior synonym for O. penetrans, and the variability of the scole x within trypanorhynch cestodes is emphasised.