A New Free-living Marine Nematode Species of the Genus Graphonema (Nematoda: Chromadorida: Chromadoridae) from Antarctica

A new species of free-living marine nematode (Chromadorida: Chromadoridae), Graphonema antarcticum sp. nov., is described. The nematode was found in the shallow water of Kita-no-ura, off Syowa Station in Lützow-Holm Bay, Antarctica. Graphonema antarcticum sp. nov. is similar to G. metuliferum Kito, 1981 in the ratios of the spicules length to the body diameter at the cloaca, the well-developed gubernaculum with L-shaped lateral pieces bending at an obtuse angle and equipped with minute denticles at the distal end, and the tail length in both sexes. However, G. antarcticum sp. nov. differs from the latter in having a larger body size and presence of the lateral differentiation. The new diagnosis of the genus and the key to the species are provided. Graphonema achaeta Platonova, 1971 was transferred to Endeolophos due to the absence of the lateral pieces of gubernaculum that are present in the genus Graphonema.

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