Miljutina, M. A.; Miljutin, D. M. (2015). A revision of the genus Paracanthonchus (Cyatholaimidae, Nematoda) with a tabular key to species and a description of P. mamubiae sp. n. from the deep North-Western Pacific. Deep Sea Research Part II: Topical Studies in Oceanography. 111: 104-118.
The species-rich genus of marine free-living nematodes, Paracanthonchus Mikoletzky 1924(Nematoda: Cyatholaimidae), is revised. The genus numbers 72 valid species; twenty are indicated as species inquirenda because of poor descriptions and/or doubtful placement in the genus. Species of the genus were described from all oceans and latitudes. Of valid species, 64 ones(90%) were described from the tidal or uppersubtidal zones, four species were recorded from the medium or lower shelf, and three species are abyssal.
Thirty one species (43%) are known from Europe and the Northern Africa; 19 and 9 ones were described from South and North America (respectively); 8 ones were recorded from Asia; and 6 ones from the Australian region. The type species, Paracanthonchus caecus Mikoletzky 1924 has been recorded by a
number of authors from various oceans around the World, yet many of these specimens have only roughly resembled the type description. Evidently, this species represents a complex of closely related species.
Possibly, the same situation is in some other Paracanthonchus species, the repeated findings of which have no strong resemblance to type specimens. A tabular key to species is provided. A new abyssal species Paracanthonchus mamubiae from the Zenkevich Rise(North-Western Pacific, off North Japan, 5350 m depth) is described. The new species is characterized by: the tail, which is long with a thin, cylindrical terminal section; the absence of lateral differentiation of the cuticle; the presence of two groups of lateral pores (level of posterior part of pharynx and in cloacal region); one large dorsal tooth and two pairs of small subventral teeth combined with pharyngostomal cuticular ridges forming two denticles which may appear as a third pair of subventralteeth; 3–5 indistinct tubular preanal supplements; and a massive,
proximally paired gubernaculum possessing broad flattened plates on each distal end. Each flattened gubernacular plate bears numerous (50–60) small cusps and one large process.
Pacific, North West (= Warm + cold temperate (boreal))