Callozostron carlottae Kuekenthal , 1909

Cairns, Stephen D., 2018, Deep-Water Octocorals (Cnidaria, Anthozoa) from the Galapagos and Cocos Islands. Part 1: Suborder Calcaxonia, ZooKeys 729, pp. 1-46 : 2

Callozostron carlottae Kuekenthal, 1909 Figures 3h, 4

Callozostron carlottae Kükenthal 1909: 49-50; 1912: 334-336, pl. 22, figs 14-17, text-figs 43-47. Not: Bayer 1996: 159-161, figs 7-10 (but includes a complete synonymy); Cairns 2016: 27.

Material examined.

Nautilus NA064-77-01-A, 1 branch, 1.82° C, CDRS, and SEM stubs 2376-2378, NMNH.

Types.

Four specimens (?syntypes) are included in the original description. Their deposition is unknown.

Type locality.

Antarctica (between 60-90°E), 3397 m depth (Gauss German South Polar Expedition of 1901-1903).

Distribution.

Galápagos: east of Fernandina, 3381 m depth. Elsewhere: Antarctica, 3397 m depth.

Description.

Although only one incomplete colony is available (Figure 3h), it appears to be unbranched and 9 cm in length. Its polyps are arranged in whorls of six or seven (Figure 4a), about five whorls occurring per cm branch length; the whorl diameter is about 4 mm, including the marginal spines. The polyps are short and cylindrical (Figures 4b-d), only about 1.2-1.4 mm in height, not counting the marginal spines, which can be up to twice as long as the polyp. The actual body wall is relatively short (about 0.5 mm), the opercular scales making up the remaining length of the polyp.

The body wall scales (Figures 4f-i) are arranged in eight irregular longitudinal rows, the two distal marginal and submarginal body wall scales being quite different from the lower four or five tiers of scales, the latter (Figure 4f) being roughly elliptical to rectangular in shape, quite thin, and often having a slightly lobate distal margin. The body wall scales are slightly curved to fit the circumference of the polyp and are highly imbricate. Their outer face is perfectly smooth, their inner face covered with sparse small tubercles. There are eight marginal and usually eight submarginal scales. The marginal scales (Figures 4g, i) have a rectangular to trapezoidal base that is up to 0.6 mm in width, capped by a slender (0.1 mm in diameter basally, but attenuating to a point distally) elongate (up to 2.2 mm in length) spine, the spinose part thus contributing 75-80% of the length of the sclerite. The spine is smooth but itself covered with very small (about 15 µm in length) spines. The submarginal scales (Figure 4h) may be as large as the marginal scales, but some are only about half as long (0.75-0.90 mm in length, see below). The eight operculars (Figures 4b, e) are arranged in two alternating quartets of four, an inner quartet and an outer, the lateral edges of the outer operculars overlapping those of the inner. The opercular scales are isosceles triangular in shape with a pointed (not spinose) tip, and having a longitudinally concave, perfectly smooth outer surface and a sparsely tuberculate inner surface. They are slightly curved about 45°in order to fold over the polyp to form the operculum. The operculars are 0.7-1.0 mm in height, with a L:W of 1.9-2.6. The marginal and submarginal scales that are aligned with the four inner opercular scales are usually both large in size, whereas the submarginals associated with the outer opercular scales are often much smaller (see above) and may even be absent. The coenenchymal scales (Figure 4j) are irregular in shape but usually elongate, up to 0.65 in greater length. Like most of the other scales, they have a smooth outer surface and a sparsely tubercular inner surface, and are quite thin, and easily broken.

Comparisons.

Despite the long distance between the Antarctic type locality and the Galápagos, this specimen is identified as C. carlottae , but it does differ in several points from the original description. The Galápagos specimen has larger polyps, and thus larger opercular and marginal spines, those of the Antarctic syntypes being only 0.6 mm and 0.8 mm in length, respectively. And the Antarctic syntypes have eight or nine polyps per whorl, whereas the Galápagos specimen has only six or seven. Otherwise, the two specimens are remarkably similar, the Galápagos specimen even showing the dimorphic-sized submarginal spines ( Kükenthal 1912: fig. 43). The specimens reported by Bayer as C. carlottae are not considered conspecific, based on a difference in the size and number of rows of submarginal spines (see Cairns 2016), as well as having differently shaped marginal spines and thicker granular body wall scales.

Remarks.

This is the first report of this species subsequent to its original description, and was collected at virtually the same depth.