Oloncholaimus Mordukhovich & Zograf & Saulenko & Fadeeva 2020, gen. nov.

urn:lsid:zoobank.org:act: E9BC6A52-A7CF-4B09-81DD-A480DFB7CAAF

Genus description. Oncholaiminae. Buccal cavity armed with three teeth. The left ventrosublateral typical oncholaimoid tooth is the largest. The right ventrosublateral and dorsal teeth have complex shape (with onchium and apical antler-shaped extension) and almost equal in size. Amphidial fovea pocket-like with transverse slit-like aperture. Orthometanemes present. Demanian system well-developed, single uvette, the caudal part of the main duct forms two long sacs pierced by the terminal ducts ending in terminal pores. Two opposed testes. Spicules long, slightly curved. Gubernaculum absent. Precloacal supplementary organ present. Tail conico-cylindrical.

Etymology. Generic name is a composite of prefix ol- (initials of names Oleg and Lyudmila, in honor to the Russian nematologists Oleg Ivanovich Belogurov and Lyudmila Semenovna Belogurova who intensively studied the family Oncholaimidae) and the generic name Oncholaimus, referring to the similarity with the genus. Masculine in gender.

Differential diagnosis. Oloncholaimus gen. nov. shows all main characters of Oncholaiminae:females monodelphic-prodelphic with antidromously reflexed ovary, three teeth with left ventrosublateral the largest, Oncholaimoid type of Demanian system. New genus can be differentiated from all other genera of the family Oncholaimidae by the complex shape of dorsal and right ventrosublateral teeth with apical antler-shaped extension. In addition to the features of the structure of the teeth, Oloncholaimus gen. nov. differs from Prooncholaimus and Pseudoncholaimus by the presence of Demanian system, from Wiesoncholaimus by the absence of gubernaculum and by the size of ventrosublateral teeth (left ventrosublateral the largest vs both ventrosublateral are equal), from Fotolaimus by the absence of gubernaculum and length of spicules (long vs short), from Metaparoncholaimus by the size of ventrosublateral teeth (left ventrosublateral the largest vs both ventrosublateral are equal), from Metoncholaimus by the structure of Demanian system (two long sacs pierced by the multiple terminal ducts ending in terminal pores vs double moniliform terminal ducts), and from Oncholaimus by the length of spicules (long vs short).

Type species. Oloncholaimus piipi gen. et sp. nov.