Narella ferula, 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 : 21

Narella ferula , n. sp.

Fig. 10 A–I

Etymology. Named ferula (Latin for whip), in allusion to the flexible unbranched shape of the colony.

Type and Type Locality. Holotype, colony and SEM stubs 2502-2504, USNM 1453829 . Type Locality: EX 1705-11 - Geo 0 1, 6.370˚N, 162.31˚W (Kingman Cone, off Palmyra Atoll), 1023 m, 12 May 2017.

Material Examined. Type.

Description. The holotype is 22 mm long and consists of six whorls, but is lacking its holdfast. Judging from in situ images, the colony was unbranched (see Remarks). The whorls are evenly spaced, about 2.5–2.7 occurring every cm, each whorl having only two or three polyps; the whorl diameter is 3.6 mm. The horizontal length of the contracted polyp is 2.3–2.5 mm. Polychaete commensalism was not noted.

The basal body wall scales are relatively tall, up to 2.0 mm, the distalmost 0.7 mm projecting beyond their attachment with the medial scales as a prominent serrated cowl ( Fig. 10 A–B). The proximal edge of the dorsolateral edge of the basal scales bears several low ridges and one or two taller spurs ( Fig. 10C ). The medial body wall scales ( Fig. 10D ) are much shorter, only 0.9–1.1 mm in length, and have a toothed distal margin. The buccal scales ( Fig. 10E ) are 0.9–1.3 mm in length, quite wide, and have a slightly undulating distal edge. One pair of adaxial buccals are present, each about 0.65 mm in width ( Fig. 10F ). The ratio of the lengths of the major body wall scales is thus about: 1: 0.47: 0.66.

The abaxial opercular scales ( Fig. 10G , rightmost) are tall (up to 1.5 mm) and wide (L:W = 1.7), often being multi-tipped. The lateral operculars are 0.7–1.4 mm in length and have a L:W of about 1.8–2.2. The adaxial operculars are small (0.8–1.05 mm) with an L:W of about 2.1–3.1.

The coenenchymal scales ( Fig. 10I ) are elongate (L:W = 3.25–6.6), thin, and imbricate, measuring 0.65–2.1 mm in length. Each usually bears a tall medial ridge, sometimes as high as 0.4 mm.

Comparisons. Among the approximately 23 species of Narella having basal scales with dorsolateral ridges, Narella ferula is most similar to N. hawaiiensis Cairns & Bayer, 2007 (Hawaiian Islands, 1492–1944 m), a species that is also unbranched and has similarly shaped coenenchymal scales. Narella ferula , however, differs in having a multi-ridged dorsolateral edge of its basal scales (vs an inconspicuous single ridge), smaller polyps and thus a smaller whorl diameter, a cowl formed by the basal scales, and serrate or toothed body wall scales. Also, the two spurs ( Fig. 10C ) at the base of the basal scales may be unique for this species.

Remarks. This specimen was incidentally collected attached to a 31 cm diameter rock that was collected for geological reasons, and thus in situ photographs were not very detailed, however it can be seen from the image of the rock that the holotype colony was not a short distal branch of an otherwise branching colony but an unbranched colony about 3 cm long.

Distribution. Known only from type locality.

Figures

FIGURE 10. Narella ferula, holotype: A, stereo view of polyp whorl. B, abaxial view of polyp. C, basal scales. D, medial scales. E, buccal scales. F, adaxial buccal scale. G, opercular scales. H, coenenchymal scales in situ. I, coenenchymal scales. Scale bars in mm.