Species Diversity

Abstract

Haplocotyle japonica n. gen., n. sp. (Monogenea: Microbothriidae) is described from the skin and gill cavity of Rhino-batos hynnicephalus Richardson, 1846 (Elasmobranchii: Rajiformes: Rhinobatidae) in the Seto Inland Sea off Hiroshima Prefecture and the southern Sea of Japan off Fukuoka Prefecture, Japan. The new genus is closely related to Dermophthirioides Cheung and Nigrelli, 1983 , Dermophthirius MacCallum, 1926, Dermopristis Kearn, Whittington, and Evans-Gowing, 2010 , and Pseudoleptobothrium Young, 1967 in common morphological features (i.e., the anterior extremity of the oötype having a tetrahedral shape, the anterior aperture of a bell-shaped pharynx, and the structure of the male copulatory organ) but differs from the latter four genera by the presence of a single testis and an ovary not looping the intestinal caeca. The phylogenetic analysis based on 28S rDNA sequences suggests that the new species shows affinity with Dermophthirius and Dermopristis. All currently known species of Microbothriidae Price, 1936 are listed, and a key to 12 genera, including Haplocotyle n. gen., of the family is provided.