New insights into Diplogastrellus Paramonov, 1952 (Nematoda: Rhabditida: Diplogastroidea) with three novel and three known species from India

Three new and three known species of the genus Diplogastrellus Paramonov, 1952 are described and illustrated from India. Diplogastrellus didelphis sp. nov. is characterised by a narrow stoma; a medium-sized dorsal tooth with ventrally directed apex; an oblong median bulb, a small pyriform basal bulb; an amphidelphic reproductive system; a large uterine pouch; ventrally arcuate spicules with a 90º curvature; a stout gubernaculum, proximally notched with a long dorsal arm, distally with a sleeve and nine pairs of genital papillae. Diplogastrellus longipharyngis sp. nov. is characterised by a short tubular stoma; a medium-sized ventrally directed dorsal tooth; an ovoid median bulb and a long isthmus; heavily cuticularized almost straight spicules; a keel-like triangular gubernaculum proximally notched, a caudal margin interrupted and nine pairs of genital papillae. Diplogastrellus robustus sp. nov. is characterised by a medium-sized dorsal tooth with a ventrally directed apex; an ovoid median bulb; a mono-prodelphic or amphidelphic reproductive system; robust spicules, with a blunt distal tip; a boat-shaped gubernaculum with a prominent distal sleeve and nine pairs of genital papillae. Three known species, viz., D. gracilis, D. graciloides and D. monhysteroides are redescribed/illustrated with emended diagnosis and SEM details. The comparative analysis of morphometrics and morphological traits as well as cladogram based on morphological characters are provided besides their biogeographic distribution.