Calyptrophora pourtalesi, 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 : 14-16

Calyptrophora pourtalesi , n. sp.

Figs. 1F , 7 A–L

Etymology. Named in honor of Count Louis François Pourtalès (1824–1880), early contributor to our knowledge of deep-sea Scleractinia, Stylasteridae, and Octocorallia ( Agassiz 1905), and author of the closely related species C. trilepis .

Type and Type Locality. Holotype: colony and SEM stubs 2505-2508, USNM 1453726 . Type Locality: EX 1703-8-01, 0.210˚N, 176.48˚W (off Baker Island, Phoenix Islands), 437 m, 16 March 2017.

Material Examined. Type.

Description. The holotype ( Fig. 1F ) now consists of two branch fragments, each about 23 cm in height, which display equal, dichotomous branching, the distance between each bifurcation about 3–4 cm. Polyps are directed upward ( Fig. 7 B–C) and are arranged in whorls of four or five (seven or more on larger-diameter branches), 4–4.5 whorls occurring per cm branch length; the whorl diameter is about 3.5 mm. Individual polyps are 2.0– 2.4 mm in horizontal length.

The fused basal scale ( Figs. 7D, G ) is 1.3–1.4 mm in height, projecting only slightly (0.06–0.10 mm) beyond the articular ridge as a thin shelf ( Fig. 7G ), but not expressed as a spine or tooth. The articulating ridge is distinct and because of the short basal shelf, can be seen even from the outer surface of a bent polyp ( Fig. 7F ). The fused buccal scale ( Fig. 7D ) is larger (1.7–1.8 mm in length), having a rounded, finely serrate distal edge, the serrations being equilateral triangles about 8 µm in height ( Fig. 7H ); there is essentially no cowl. The outer surface of both types of body wall scales is uniformly covered with low granules. There is one pair of prominent, crescent-shaped infrabasal scales ( Figs. 7C, I ), which may be up to 1.3 mm in length and 0.45 mm in maximum height; often each bears one or more vertical radiating low ridges.

The operculum is quite low ( Fig. 7J ), almost flat in the contracted condition, the opercular scales ( Figs. 7K ) being relatively similar in shape and size; they have a concave outer surface and a keeled inner surface. The adaxial operculars are symmetrical, 0.72–0.89 mm in length, and have an L:W of 1.25–1.40; the lateral, slightly asymmetrical operculars are 0.65–0.80 mm in length, with an L:W of 1.15–1.30; and the adaxial operculars are also asymmetrical, 0.50–0.60 mm in length, with a very broad base resulting in a low L:W of 0.85–1.00.

The coenenchymal scales ( Fig. 7L ) are elongate (L:W = 3.5–7.5), slightly irregular in shape, flat, and bear low granules (no ridging) like the body wall scales.

Comparisons. Calyptrophora pourtalesi , a member of the japonica species complex, is remarkably similar to C. trilepis (Pourtalès, 1868) , a species known only from the tropical western Atlantic from 593–911 m, and might even be considered as a sister species. C. trilepis differs only in having smaller polyps (1.3–1.6 mm in length, and thus a smaller whorl diameter) and fewer polyps per whorl (2–4). Although redescribed by Bayer (2001), both species are known from very few specimens and thus comparisons are tentative. Within the Pacific C. pourtalesi is most similar to C. japonica Gray, 1866 , but that species has a biplanar, bipectinate colony.

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 7. Calyptrophora pourtalesi, holotype: A, stereo opercular view of two polyps. B–C, stereo views of abaxial and lateral sides of a polyp. D, stereo view of inner side of buccal scale. E, basal scale. F, articulation of basal to buccal scale. G, distal margin of a basal scale. H, distal edge of a buccal scale. I, infrabasal scales. J, polyp operculum. K, opercular scales. L, coenenchymal scales. Scale bars in mm.