Macroprimnoa Cairns 2018, gen. nov.

Genus Macroprimnoa, gen. nov.

Type Species. Macroprimnoa ornata, here designated.

Etymology. From the Greek makros (meaning long) and primnoa (a common primnoid suffix), meaning a primnoid with long (and large) polyps. Gender: feminine.

Diagnosis. Colonies unbranched (flagelliform). Polyps uniserially arranged, oriented perpendicular to branch, and well spaced. Body wall scales in eight longitudinal rows of only two or three scales each. Opercular scales keeled. Coenenchymal scales elongate and prominently ridged.

Discussion. Macroprimnoa is unique among the 48 other primnoid genera (Cairns & Wirshing 2018) in having unilinearly arranged (uniserial) polyps. It is also distinctive, although not unique, in having very large and widelyspaced polyps, and in having very few body wall scales. Superficially it resembles Abyssoprimnoa in polyp shape, coenenchymal ornamentation, and extreme depth of capture, but Abyssoprimnoa differs in being dichotomously branched, having paired polyps, and in having only four (marginal) body wall scales. In the key to the genera pub-

lished by Cairns & Wirshing (2018), Macroprimnoa keys close to Helicoprimnoa and Callozostron, but is easily distinguished from those genera by numerous characters. Distribution. Central Pacific (see below), 3066–3676 m.