Steinernema tarimense n. sp. (Rhabditida: Steinernematidae), a new entomopathogenic nematode from Tarim Basin, Xinjiang, China.

A novel entomopathogenic nematode (EPN) species, Steinernema tarimense n. sp., was isolated from soil samples collected in a Populus euphratica forest located in Yuli County within the Tarim Basin of Xinjiang, China. Integrated morphological and molecular analyses consistently place S. tarimense n. sp. within the 'kushidai-clade'. The infective juvenile (IJ) of new species is characterized by a body length of 674-1010 μm, excretory pore located 53-80 μm from anterior end, nerve ring positioned 85-131 μm from anterior end, pharynx base situated 111-162 μm from anterior end, a tail length of 41-56 μm, and the ratios D% = 42.0-66.6, E% = 116.2-184.4, and H% = 25.5-45.1. The first-generation male of the new species is characterized by a curved spicule length of 61-89 μm, gubernaculum length of 41-58 μm, and ratios D% = 36.8-66.2, SW% = 117.0-206.1, and GS% = 54.8-82.0. Additionally, the tail of first-generation female is conoid with a minute mucron. Phylogenetic analyses of ITS, 28S, and mt12S sequences demonstrated that the three isolates of S. tarimense n. sp. are conspecific and form a sister clade to members of the 'kushidai-clade' including S. akhursti, S. anantnagense, S. kushidai, and S. populi. Notably, the IJs of the new species exhibited faster development at 25°C compared to other Steinernema species. This represents the first described of an indigenous EPN species from Xinjiang, suggesting its potential as a novel biocontrol agent against local pests.