Diplogastrellus metamasius n. sp. (Rhabditida: Diplogastridae) isolated from Metamasius hemipterus (L.) (Coleoptera: Dryophthoridae) in southern Florida and Costa Rica

Diplogastrellus metamasius n. sp. (Rhabditidae) was cultured from dauer juveniles recovered during dissections of the West Indian sugarcane weevil, Metamasius hemipterus (Coleoptera: Dryophthoridae), from southern Florida and Costa Rica. Morphological studies of these two isolates with light microscopy and SEM revealed many typological differences between it and the closest putative relative. Based upon molecular and mating studies, the two isolates are conspecific and are described herein as Diplogastrellus metamasius n. sp. Diplogastrellus metamasius n. sp. is characterised by stomatal structure, i.e., cheilostom with thin adradial cuticular flaps, anterior region of gymnostom ring strongly cuticularised and refractile, stegostom forming a structure resembling a 'glottoid' apparatus and possessing a movable, flap-like, dorsal tooth with small ventral ridges, oblong (elongated) median bulb in both sexes, single gonad with short (less than one vulva body diam.) postuterine sac, well developed ovary reflexed posteriorly beyond the vulva, tapered to filiform tail in both sexes, relatively large gubernaculum in males (with arcuate anterior part and pointed distal part in lateral view) and arrangement of the nine pairs of male genital papillae, especially the position of first two pairs which are located far anterior to the cloacal slit. Because of the many possibilities for homoplasy in the morphological characters possessed by the new species and described species in the 'sister' genera of Butlerius, i.e., the arrangement of male caudal papillae, and Paroigolaimella, i.e., the arrangement of cheilostomatal flaps, molecular analysis of more members of these putative clades is necessary before unambiguous generic placement of this new species is possible.