Steinernema riojaense n. sp., a new entomopathogenic nematode (Nematoda: Steinernematidae) from Spain

Abstract

A new species of entomopathogenic nematode, Steinernema riojaense n. sp., was isolated during a survey in La Rioja province of Spain. Morphological and morphometric traits place the new species in the glaseri-group, which is characterised by having the largest infective juvenile (IJ) with an average body length in excess of 1000 μm. The IJ of S. riojaense n. sp. possess a body length of 1043 (869-1172) μm, the lateral fields are formed by eight equally spaced and developed ridges (nine incisures) in the mid-body region, giving the formula 2, 6, 8, 4, the excretory pore is located posterior to the mid-pharynx region (D% = 58), and the hyaline region occupies ca half of the tail length. The male spicules are moderately curved with a sharp tip and are golden-brown in colour with the manubrium elongate and having a length to width ratio of 1.7:1. The first-generation male tail is non-mucronate, whereas a small papilla-like mucron is developed in the second generation. There are 11 pairs of genital papillae plus a single precloacal papilla. The first-generation female possesses a moderately protruding vulva and a slightly protruding postanal swelling. The second-generation female possesses a slightly protruding vulva and a postanal swelling. The new species is further characterised by sequences of the internal transcribed spacer (ITS) and partial 28S regions (D2-D3) of the ribosomal DNA (rDNA). Phylogenetic analyses confirm that S. riojaense n. sp. belongs to the glaseri-group and forms a monophyletic subclade with other European species.