Neoalloionema tricaudatum gen. n., sp. n. (Nematoda: Alloionematidae) associated with a cyclophorid snail in Cuc Phuong Natural Park, Vietnam

A new nematode genus and species associated with terrestrial gastropods from Vietnam is described and illustrated. Partial SSU and ITS rDNA sequences were obtained and subjected to phylogenetic analysis. Both morphologically and molecularly,Neoalloionema tricaudatumgen. n., sp. n. is closest toAlloionemaappendiculatum, another gastropod associate. It is differentiated fromA. appendiculatumby the presence of an outstretchedvsreflexed testis and the absence of denticles in the stoma, by the parasitic juveniles inhabiting the pallial cavityvsthe foot of the host and having sixvstwo lips and large sucker-like phasmidsvspore-like. The most peculiar feature ofN. tricaudatumgen. n., sp. n. is the presence of paired, solid appendages located at the mid-tail region of juveniles from the pallial cavity of the host. The nature of the association betweenN. tricaudatumgen. n., sp. n. and its gastropod host is discussed.