Key to species of Graphonema 1 Gubernaculum (whole length) much longer than a half of spicule length···················································································· 2 – Gubernaculum either almost equal to or shorter than a half of spicule length ············································································ 3 2 Body shorter than 2.0 mm, spicules approximately 1.5 abd long······································································ G. mediterraneum – Body longer than 2.5 mm, spicule length equal to abd··································································································· G. arcticum 3 Spicules shorter than 30 µm ······································································································································· G. parafricanum – Spicules equal to or longer than 40 µm ··············································································································································· 4 4 Tail 7–9 abd long in both sexes ································································································································· G. northumbriae – Male tail either equal to or shorter than 6 abd··································································································································· 5 5 Gubernaculum thin, weakly developed ·············································································································································· 6 – Gubernaculum and lateral pieces well-developed····························································································································· 7 6 Spicule length almost equal to abd ······································································································································· G. georgei – Spicules twice as long as abd·················································································································································· G. vulgare 7 Proximal end of spicules with a set-off capitulum········································································································· G. amokurae – Proximal end of spicules with a not set-off capitulum························································································································ 8 8 Gubernaculum without tiny projections at distal end····································································································· G. scampae – Gubernaculum with tiny projections at distal end···························································································································· 9 9 Body shorter than 1.5 mm, lateral differentiation absent ························································································· G. metuliferum – Body equal to or longer than 2.0 mm, lateral differentiation present······················································· G. antarcticum sp. nov.

Published as part of Shimada, Daisuke, Tsujimoto, Megumu & Watanabe, Kentaro, 2019, A New Free-living Marine Nematode Species of the Genus Graphonema (Nematoda: Chromadorida: Chromadoridae) from Antarctica, pp. 61-67 in Species Diversity 24 (1) on page 66, DOI: 10.12782/specdiv.24.61, http://zenodo.org/record/4585216