Abstract
Paradeontacylix buri n. sp. is described based on specimens from the afferent branchial arteries of the Japanese amberjack Seriola quinqueradiata cultured in Mie and Oita Prefectures, Japan. The new species can be differentiated from congeners by a body of up to 4.15 mm with lanceolate tegumental spines of the same size throughout the body, uterus ascending after leaving the oötype and the vitellarium not extending posterior to the ovary. P. buri n. sp. is unique among Paradeontacylix species from Seriola spp. in having the same size tegumental spines throughout the body. A phylogenetic analysis based on the sequences of the internal transcribed spacer 2 and on the 28S rRNA-gene demonstrated that P. buri is grouped with other Paradeontacylix species from Seriola spp., indicating that the enlarged tegumental spines in the posteriormost rows in the other Paradeontacylix spp. from Seriola spp. are not a morphological feature at the generic level. Another blood fluke, Paradeontacylix sp., is described based on a single specimen from the afferent branchial artery of yellowtail amberjack S. lalandi cultured in Oita Prefecture, Japan. This species may be differentiated from the most similar P. buri n. sp. by the cirrus (conical and thick walled in Paradeontacylix sp. vs. spherical and thin-walled in P. buri) and by the uterus (extending posteriorly up to the level of the oötype vs. extending posterior to the oötype).
