Steinernema jollieti sp n. (Rhabditida : Steinernematidae), a new entomopathogenic nematode from the American midwest

摘要

Steinernema jollieti sp. n. is described from a soil sample collected in a woodland in the Missouri valley near St. Louis, USA in 1999. The general morphology and sequences of the ITS-rDNA indicate that the new species is related to species with widespread distribution, such as S. feltiae and S. kraussei. A characteristic feature of S. jollieti sp. n. infective juveniles is the presence of only 6 equal and equally spaced longitudinal ridges in the lateral field at the mid-body. Infective juveniles of S. jollieti sp. n. are also characterized by their straight or only slightly curved body when heat-killed, by the shape of their "medium" length (average 800-900 pin), the excretory pore at the mid-pharynx position and a hyaline tail portion of about half of the total tail length. Only males of the second generation have a mucron on the tail tip. Spicules are dark-yellow, 55-70 mum or 48-63 mum long in the first and second generation, respectively. According to ITS rDNA sequences, S. jollieti sp. n. belongs to the Steinernema clade composed of species such as S. kraussei, S. feltiae, S. weiseri, and S. oregonense. The new species shows a high level of nucleotide differences in ITS rDNA sequences with all these steinemematid species.