Narella fordi, Cairns, 2018

Cairns, Stephen D., 2018, Primnoidae (Cnidaria: Octocorallia: Calcaxonia) of the Okeanos Explorer expeditions (CAPSTONE) to the central Pacific, Zootaxa 4532 (1), pp. 1-43 : 25-27

Narella fordi , n. sp.

Figs. 1O , 12 A–J

Etymology. Named in honor of Robert H. Ford, terrestrial plant ecologist, teacher, and colleague.

Type and Type Locality. Holotype: Six branches of the same colony, SEM stubs 2494-2497, USNM 1453764 . Type Locality: EX 1703-18-02, 6.4916˚S, 173.581˚W (Te Kaitira, seamount south of Phoenix Islands), 1899 m, 25 March 2017.

Material Examined. Holotype.

Description. Judging from in situ images of the holotype prior to collection ( Fig. 1O ), only the distal third of the colony was collected, consisting now of six branch fragments, the largest only 8 cm in length. The intact colony was about 30 cm in height and had very sparse, equal dichotomous branching. The color of the colony is white. The whorls are evenly spaced at 2.5–3.0 per cm, each whorl having three polyps; the whorl diameter is 3.4–3.5 mm. The horizontal length of a contracted polyp is 2.1–2.6 mm. Polychaete commensalism was not noted.

The basal body wall scales are relatively short, only 0.8–1.1 mm in length, having a rounded distal margin. The dorsolateral edge of the basal scale is also rounded but bears a series of low ridges on its proximal surface ( Fig. 12D ). The basal scales are open on the adaxial side, separated by a pair of rectangular ridged adaxial buccal scales ( Figs. 12C, G ), each measuring 0.29–0.40 mm in greater width. The medial body wall scales ( Fig. 12E ) are also relatively short (0.8–0.9 mm), each bearing a low continuous dorsolateral ridge. The buccal body wall scales ( Fig. 12F ) are the largest of the scales, up to 1.2 mm in length, and have a rounded dorsolateral edge devoid of ridges. The ratio of the lengths of the major body wall scales is thus about: 1: 0.85: 1.2, all scales being almost the same length.

The abaxial opercular scales are symmetrical, with small lobes on each lateral side, and measure up to 1.3 mm in length (L:W = 1.6). The lateral opercular scales are asymmetric, each having only one lateral lobe on its adaxial side, and measure 1.2–1.3 mm in length (L:W = 2.0–2.3). The adaxial operculars are quite slender ( Fig. 12H , lower left), symmetrical, lack lateral lobes, and measure 1.0– 1.1 mm in length (L:W = 3.4).

The coenenchymal scales ( Fig. 12J ) vary from square to elongate (L:W = 1.1–4.0), thin, imbricate, and measure up to 1.2 mm in length. They usually bear tall, complex ridges on their outer surface.

Comparisons. Narella fordi is most similar to N. cristata Cairns & Baco, 2007 , a species found in much deeper water (i.e., 3385 m) in the Gulf of Alaska. It differs in having a series of ridges on the dorsolateral edge of its basal scales ( N. cristata has only one), lacking a ridge on the dorsolateral edge of the buccal scales and in having more complex coenenchymal ridging.

Remarks. A large orange ophiuroid was attached to the holotype colony ( Fig. 1O ).

Distribution. Known only from the type locality.

Figures

FIGURE 1. In situ images of various species: A, Callogorgia cracentis, holotype. B, Calyptrophora lyra, holotype (not in situ). C, C. diaphana, EX1606-9-1. D, C. carinata, holotype. E, C. clarki, EX1605-L3-6. F, C. pourtalesi, holotype. G, C. distolos, holotype. H, Candidella gigantea, EX1606-6. I, Macroprimnoa ornata, holotype. J, Narella virgosa, holotype. K-L, N. aurantiaca, holotype. M, N. merga, holotype. N, N. horrida, EX1703-2-3. O, N. fordi, holotype. P, N. calamus, holotype. Q, N. virgosa, paratype, EX1504-L4-9-4. R, N. macrocalyx, EX1606-7. S, N. hawaiiensis, EX1504-9-2. T, Paracalyotrophora hawaiiensis, EX1703-2-1. U, P. echinata, EX1703-10-1. V, P. spiralis, holotype. W, Plumarella circumoperculum, EX1603-2-3. X, Thouarella hilgendorfi, EX1605-L1-17.

FIGURE 12. Narella fordi, holotype: A–C, stereo views of lateral and adaxial sides of a polyp. D, outer surface of basal scales. E, medial scale. F, buccal scales. G, adaxial buccal scale. H, opercular scales. I, coenenchymal scales in situ. J, coenenchymal scales. Scale bars in mm.