Abstract
Species of Seuratascaris Sprent, 1985 are a rarely reported group of ascaridoid nematodes, parasitising various frogs and toads. In the present study, a new subspecies of Seuratascaris, S. physalis bazhaiensis n. subsp. was described using integrated taxonomic methods, based on specimens collected from Odorrana graminea (Anura: Ranidae) in Guangxi Zhuang Autonomous Region, China. Results of the Assemble Species by Automatic Partitioning (ASAP) and Bayesian inference based on the mitochondrial cox1, cox2 and rrnS data all supported S. physalis bazhaiensis representing a distinct taxon from the nominate subspecies S. physalis physalis. Supplementary morphometric and genetic data of S. phy. physalis are presented based on newly collected material from Odorrana tiannanensis (Anura: Ranidae) and Rhacophorus sp. (Anura: Rhacophoridae) in Yunnan Province, China. A key to species of Seuratascaris is provided. The complete mitochondrial genome of S. physalis bazhaiensis was sequenced and annotated, and represents the first mitogenomic data for the genus Seuratascaris. This mitogenome has only 13,628 bp (including 12 protein-coding genes, 22 tRNA genes, 2 ribosomal RNAs, and only 1 non-coding region), and is the smallest of the reported ascaridoid mitogenomes so far.