Steinernema unicornum sp. n. (Panagrolaimomorpha: Steinernematidae), a new entomopathogenic nematode from Tierra del Fuego, Chile

Abstract

A new species of entomopathogenic nematode,

Steinernema unicornum sp. n., was isolated from a soil sample taken from the archipelago of Tierra del Fuego, southern Chile. The new species is characterised by a prominent, dorsally located, horn-like tooth on the cephalic extremity of the infective juvenile (a feature unique for the family); lateral field pattern of 2, 6, 8, 4 ridges; and morphometrics of the infective juvenile with body length of 732 (654-786) μm, excretory pore located 55 (48-62) μm posterior to the cephalic extremity, tail 60 (50-71) μm long, H% = 37 (24-49), E% = 91 (77-116) and a ratio = 25.4 (21.9-29.4). The first generation male has spicules 73 (60-82) μm long, gubernaculum 48 (44-52) μm long and SW% = 198 (184-217). The first generation female can be recognised by the presence of a series of transverse cuticular folds and ridges located immediately anterior and posterior to the vulva, the lack of a prominent post-anal swelling, and presence of a mucron-like projection on the tail tip. Sequences of the ITS and D2D3 regions of the ribosomal DNA confirm that S. unicornum sp. n. is a valid species.