Paracalyptrophora spiralis, 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 : 37

Paracalyptrophora spiralis , n. sp.

Figs. 1V , 18A–K

Etymology. Named spiralis (Latin for coiled, spiral or twisted) in allusion to the spirally coiled nature of the secondary branches of the colony.

Type and Type Locality. Holotype: colony and SEM stubs 2519-2521, 2527, USNM 1453670 . Type Locality: EX 1702-13-01: 14.32˚S, 170.65˚W (off Tutuila , American Samoa), 345 m.

Material Examined. Types.

Description. The holotype, now in four pieces, consists of an elongate basal stem about 20 cm in length, which bifurcates, each secondary branch giving rise to a series of branchlets on one side of the secondary; the two secondary branches ascend in a loose spiral. The branchlets are up to 9 cm in length and often bifurcate once. Thus, the branching can be described as lyrate, followed by dichotomous terminal branchlets; colony flaccid (not stiff). Most of the holotype was collected ( Fig. 1V ), the entire colony measuring about 40 cm in height. The whorls are widely spaced (four whorls per cm), each whorl having three (sometimes two) polyps (Fig. 18A), all of which point downward; the whorl diameter is 2.2–2.3 mm. The horizontal length of a contracted polyp is 1.6–2.0 mm.

The basal body wall scales are 0.9–1.1 mm in height and terminate in a straight-edged (about 0.20–0.25 mm in width), short (about 0.07 mm in height) extension, the inner face constituting the articular ridge (Figs. 18D–E). The outer surface of the basals, and all other body wall and coenenchymal scales, bear low granules (not ridged). The buccal body wall scales (Fig. 18F) are slightly longer (1.1–1.3 mm), terminating in a rounded to slightly undulating distal margin. The adaxial side of both the basal and buccals are quite open. Most polyps have one pair of curved infrabasal scales (Figs, 18G–H), 0.25–0.30 mm in height, but polyps often lack these scales. Four large (greater axis 0.3–0.45 mm) elliptical adaxial buccals occur below the two adaxial and outer lateral opercular scales and another pair occur below these (Figs. 18C, I).

All of the opercular scales (Fig. 18J) are isosceles triangles and quite elongate, having a high L:W ratio. The abaxial operculars are up to 1.1 mm in length, having an L:W of 2.5–2.6. The lateral operculars measure 0.85–0.95 m in length, with an L:W of 2.6–2.7. The adaxial operculars are only 0.65–0.75 mm in length, with an L:W of 2.8–2.9.

The coenenchymal scales (Fig. 18K) are elongate (L:W = 3.3–4.6), thin, slightly imbricate, and flat, their distal ends rounded.

Comparisons. Paracalyptrophora spiralis is unique among the nine known species in the genus in its branching form (uniplanar/spiral: lyrate followed by dichotomous). It is also distinctive in having so few polyps per whorl (usually three), most other species having four or more. It also has a very open adaxial polyp side, allowing at least six large adaxial body wall scales to cover this region, and it has very small distal extensions on its basal scales.

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.