Bucephalids (Digenea: Bucephalidae) from marine fishes off the south-western coast of Java, Indonesia, including the description of two new species of Rhipidocotyle and comments on the marine fish digenean fauna of Indonesia

Abstract

Two new bucephalids are described from marine fishes from off the southern coast of Java, Indonesia. Rhipidocotyle danai n. sp. from the gempylid Thyrsitoides marleyi and R. jayai n. sp. from the sciaenid Johnius macropterus. Neither has previously been reported as host of members of the genus Rhipidocotyle. They can be distinguished from other species within the genus by a suite of characters, including the body shape, rhynchus length, pre-vitelline, pre-uterine, pre-mouth and post-testicular distances, cirrus-sac reach and egg length. Prosorhynchus platycephali is reported from the platycephalid Sunagocia otaitensis. This identification is based on the distinctly separated testes and the position of Mehlis' gland directly posterior to the anterior testis. To aid identification within these species-rich trematode genera, we have devised an illustrated metrical key that indicates the most similar described species. Nine distinct metrical features were recorded or calculated for all known marine species within Rhipidocotyle (51 known species) and Prosorhynchus (64 known species) and utilised in species identification. With about 75 identified fish trematode species, only a fraction of the expected species diversity has been recorded from Indonesia, strongly suggesting the need for greater effort for fish parasitological research in the region.