Synopsis of the genus Greeffiella (Nematoda: Desmoscolecida), with the description of two new species from the Sea of Japan and the Black Sea

Abstract

The genus Greeffiella Cobb, 1922 includes twelve species inhabiting all oceans of the world. Updated brief and illustrated diagnoses, an identification key and data on the geographical and bathymetrical distribution of all Greeffiella species are given. Two new species are described and illustrated: G. japonica sp. nov. from the Sea of Japan and G. pontica sp. nov. from the Black Sea. The genus is recorded from the Sea of Japan for the first time, and G. japonica sp. nov. completes the list of the free-living nematode species inhabiting the shelf of the Far Eastern seas of Russia. This species is characterised by 70 annules dorsally and 62 ones ventrally, the ocelli located on the annules 19 and 29, somatic setae 11‒25 μm long, six pairs of subdorsal tubular setae on the body, the vulva surrounded by dense fine hair-like setae, located between the annulus 37 and 38, the tubular anus, and the terminal tube 10 μm long. Greeffiella pontica sp. nov. mentioned by the authors in 2021 as Greeffiella sp. was collected in the northwestern shelf of Crimea (the Black Sea) at a depth of 56 m and is characterised by the following characters: 67‒70 annules dorsally and 67‒68 ones ventrally, the absence of ocelli, somatic setae 12‒42 μm long, seven pairs of subdorsal tubular setae on the body, the vulva surrounded by short sparse setae, not visible anus, and the presence of three thin terminal tubes 13 μm long.