Narella valentine, Taylor & Rogers, 2017

Taylor, M. L. & Rogers, A. D., 2017, Primnoidae (Cnidaria: Octocorallia) of the SW Indian Ocean: new species, genus revisions and systematics, Zoological Journal of the Linnean Society 181, pp. 70-97 : 82-85

NARELLA VALENTINE SP. NOV.

( FIGS 2A, 8, 9)

Material examined: Holotype – NHMUK 2016.34 ( JC66-3807 ), RRS James Cook, sta. 7, ev. 10, Sapmer Bank, 36°48′10.284′S, 52°06′55.706′E, 383–444 m, December 2011 . Paratypes: NHMUK 2016.35 ( JC066- 3808 ) , NHMUK 2016.36 ( JC066-3813 ) , same details as holotype. SEM stubs – T149-150 .

Description: Holotype uniplanar, 32 cm tall, 17 cm wide, with true lyrate branching and rare secondary dichotomous branching, terminal branches generally long (in situ, Figs 2a, 8b), no holdfast. Polyps 1.5–1.8 mm tall ( Fig. 8d), 4–5 polyps per whorl on branchlets, main branches ~8 polyps per whorl, 15–16 whorls per 3 cm of branchlet ( Fig. 8a), whorl diameter 2.4–2.8 mm.

Basal scales ( Fig. 9n–p) modest size (1.25–1.45 mm tall) in comparison to medial scales ( Fig. 9j–m); 1:0.8:0.8 ratio of major body-wall scales. Basal scale distal edge peaked, joined to adjacent basal scale forming a sculpted cowl ( Fig. 8c). Outer basal scale surfaces have lateral crest or ridge. Basal scales form closed ring. No infrabasal scales.

Medial scales square-shaped ( Fig. 9j–m), with peaked distal edge, rounded dorso-lateral edge, very slight curve to outer surface, 0.64–0.74 mm tall.

Buccal scales ~ 0.8 mm tall with rounded distal edge, scale base and lateral edges straight ( Fig. 9h, i). One pair of square-to-oblong adaxial buccal scales cover adaxial side of polyp.

Operculum visible from lateral view, forming onethird of polyp height. Opercular scales reduce in size from abaxial to adaxial; generally 0.3–0.66 mm tall. Opercular scales wide with a lateral wing (0.5 mm, Fig. 9c) or lanceolate-shaped ( Fig. 9a, d, f, g), strongly keeled (lateral keel view, Fig. 9b).

Little coenenchyme visible as polyp whorls closely placed. One layer of long, thin coenenchymal scales ( Fig. 9q), some smaller sclerites arranged around them ( Fig. 9r); outer surfaces ridged, inner granular ( Fig. 9s). No tentacular scales noted.

Known distribution: Sapmer Bank, SW Indian Ocean, 383–444 m depth.

Etymology: Named in honour of Dr Taylor’s mother, Valerie, after her secret spy name, Valentine. And in honour of Dr Taylor’s sister, Claire, who was born on Valentine’s Day. As a non-Latin word, ‘valentine’, is treated as indeclinable under 31.2.3 of the International Code of Zoological Nomenclature (ICZN).

Comparisons: As described in comparisons of N. gilchristi , lyrate branching occurs in just four species of Narella . Calyces of Narella valentine sp. nov. are smaller than those of N. gilchristi . Polyps of the former have a peaked basal cowl, whereas those of the latter have two rounded lobate projections, and they differ in number of polyps per whorl and whorl density.

Polyps of N. compressa are of a similar size to those of N. valentine sp. nov. However, the basal scale of the former is larger and there is no mention of a crest or ridge, as is found in the latter. The basal scales of N. bellissima have a rounded lobate distal edge whereas those of N. valentine have a short point. Operculars of the former are thicker and more rounded than the more delicate opercular of the latter. The basal scales of polyps of N. gilchristi are rounded distally, unlike the peaked edges seen in N. valentine .

There are three species of Narella where branching patterns are unknown: N. ornata , N. hawaiinensis and N. ambigua . The largest polyps found on N. valentine are ~ 2 mm tall. Polyps of the three species mentioned are much larger, all over 3 mm tall. With little further information about N. ambigua it is hard to make further comparisons. Both N. ornata and N. hawaiiensis , although with similar ridged basal scales as N. valentine , have far fewer polyps per whorl and basal scales that do not form a closed ring.