A new species of Prosorhynchoides Dollfus, 1929 (Digenea: Bucephalidae) from Xenentodon cancila Hamilton, 1822 in Mizoram, Northeast India.

Prosorhynchoides aspinosus n. sp., a new species of digenean trematode, is described based on morphological, ultrastructural and molecular data from the freshwater fish, Xenentodon cancila Hamilton, 1822, of Tuikum and Tuirial river in Mizoram, Northeast India. It differs from its congeners in the absence of tegumental spines and the length of cirrus sac. These unique morphological characteristics were further supported by the ultrastructural data showing distinct knob-like protrusions in the tegument. Each knob-like protrusion is without cutting plates or spines and appears granulated at higher magnification. The molecular data analyses, along with the sequences of other Prosorhynchoides available in the Genbank, using internal transcribed spacer 2 and 28S rDNA revealed a gap of 4% K2P (Kimura 2 parameter) distance with its closest congener, P. karvei, confirming the novelty of the species, and thus, clearly differentiates the new species from all other valid Prosorhynchoides spp.