Four trypanorhynchs, Kotorella pronosoma (Stossich, 1901), Nybelinia cf. bisulcata (Linton, 1889), Nybelinia scoliodoni (Vijayalakshmi, Vijayalakshmi ct Gangadharam, 1996), and Dasyrhynchus pacificus Robinson, 1965 are reported for the first time from the Gulf, which is now known to harbour at least 34 different species. In addition to the range extension for the trypanorhynchs listed above, 21 new host records are reported involving 13 cestode species. Characters of the genus Kotorella Euzet et Radujkovic, 1989 are emended, Nybelinia narinari MaeCallum, 1917 is considered a junior synonym of Kotorella pronosoma (Stossich, 1901), and Heteronybelinia palliata (Linton, 1924) comb. n. is redescribed. The usefulness of the bulb ratio as a means to distinguish different tentaculariid species is discussed, and the importance of shallow water localities for the life cycle of trypanorhynch ccstodes is emphasised.
Results of a study on trypanorhynch ccstodes of fishes from Indonesian coastal waters are presented. A new species, Dasyrhynchus thomasi sp. n., is described, and five species are recorded which all represent new locality records: Tentacularia coryphaenae Bose, 1797; Nyhelinia africana Dollfus, 1960; Nybelinia scoliodoni (Vijayalakshmi, Vijayalakshmi et Gangadharam, 1996); Sphyriocephalus dollfusi Bussieras et Aldrin, 1968; and Otobothrium penetrans Linton, 1907, Their known ranges of distribution are extended to the East-Indian Ocean. Scanning and transmission electron microscopy was used to clarify details of the tentacular armature and surface morphology of T. coryphaenae, D. thomasi and O. penetrans. In T. coryphaenae, hook-like microtriches along the bothridial tegument are embedded in the distal cytoplasm, sometimes showing a split base. The solid tentacular hooks are embedded into a fibrillar, highly ordered tentacular wall. D. thomasi is distinguished by its characteristically shaped bothridia and a triple chainette with winged hooks on the external surface of the tentacle. Tufts of microtrichcs with ciliated sensory receptors arc regularly arranged on the bothridial surface of O. penetrans. They show similarities to sensory receptors reported from other trypanorhynch cestodes. Otobothrium pephrikos Dollfus, 1969 is considered a junior synonym for O. penetrans, and the variability of the scolex within trypanorhynch cestodes is emphasised.