Description of Ruehmaphelenchus formosanus n. sp (Tylenchina: Aphelenchoididae) isolated from Euwallacea fornicates from Taiwan

A Ruehmaphelenchus species was isolated from an ambrosia beetle, Euwallacea fornicates, during a biodiversity survey of entomophilic nematodes in Taichung, Taiwan. The new species is characterised by a unique tail morphology in both males and females, and a unique spicule morphology in males. The male spicule has clear dorsal and ventral limbs (connected by a blade-like cuticle), a triangular membrane-like structure on its sides, and short, conspicuous, laterally oriented, projections at the distal end. In a molecular phylogenetic tree, inferred from near-full-length small subunit (SSU: 18S) and D2/D3 expansion segments of the large subunit (LSU: 28S) of ribosomal RNA, the new species and other nominal and undescribed Ruehmaphelenchus species formed a well supported clade within Bursaphelenchus. Although this result supports a previous study that suggested that Ruehmaphelenchus is a junior synonym of Bursaphelenchus, the generic relationship between Ruehmaphelenchus and Bursaphelenchus remains somewhat uncertain. Therefore, R. formosanus n. sp. is described as a member of Ruehmaphelenchus, although this should be regarded as a tentative placement.