dcsimg

Comprehensive Description

provided by Smithsonian Contributions to Zoology
Rhombopsammia niphada Owens, 1986

Rhombopsammia niphada Owens, 1986a:252–255, figs. 2B, 3A-D.—Cairns, 1989a:19–20, text-fig. 2, pl. 9: figs. d-i; pl. 10: figs. a,b [synonymy].

DIAGNOSIS.—Discoidal corallum up to 41.6 mm in diameter; base usually flat. Costae thin (0.06–0.07 mm) ridges. Intercostal regions much wider (about 0.45 mm) than costae, traversed by thin synapticulae, which produce a series of pores in each elongate space. Septa arranged in typical micrabaciid fashion, both costae and septa attaining 144 elements. Marginal shelf present but not wide and often damaged. Columella elongate and spongy.
license
cc-by-nc-sa-3.0
bibliographic citation
Cairns, Stephen D. 1994. "Scleractinia of the temperate North Pacific." Smithsonian Contributions to Zoology. i-150. https://doi.org/10.5479/si.00810282.557.i

Comprehensive Description

provided by Smithsonian Contributions to Zoology
Rhombopsammia niphada Owens, 1986

“Undescribed genus.”—Squires, 1967:505 [in part].

New Genus A.—Owens, 1986a:521, fig. 3.

Rhombopsammia niphada.—Squires, ms:13 [unpublished].

Rhombopsammia niphada Owens, 1986a:252–255, figs. 2b, 3a-d.

DESCRIPTION.—Corallum fragile, up to 41 mm in calicular diameter (USNM 72805), with GCD: H ratios of 2.8–4.0. Base usually flat, but may be slightly concave or convex. Costae and intercostal architecture very similar to that of R. squiresi. Costae tall (0.15–0.20 mm), thin (0.06–0.07 mm) ridges, each bearing a unilinear row of coarse rounded teeth about 0.08 mm in height and 0.06 mm in diameter, producing a finely serrate costal edge. Six pairs of costae unite at epicenter, each pair corresponding to one system and meeting in a V, the apex of which is directed toward the epicenter. Each arm of the V bifurcates 11 times, resulting in 12 costae per half-system (Figure 2). Following the first bifurcation of an arm, the segment nearest the S2 bifurcates three more times, whereas the segment adjacent to the S1 bifurcates seven times. This is slightly different from the pattern illustrated by Owens (1986a, fig. 2b). A total of 144 costae result, 24 per system. Intercostal width considerably greater than costal width, about 0.44 mm, and, as in R. squiresi, each intercostal space is bisected by a septal base. Septal bases resemble costae in thickness and arrangement but are easily distinguished by their recessed position and nonserrate margin. Slender cylindrical synapticulae about 0.10 mm in diameter join costae to adjacent septal bases, producing a double series of intercostal pores. These pores are round to elliptical in shape, 0.10–0.40 mm long and about 0.10 mm wide, producing a very porous, lightweight corallum base.

Septa arranged in typical micrabaciid fashion, attaining a full complement of 144 septa at a calicular diameter of 27–29 mm. S1–S3I are very similar in size and shape to those of R. squiresi, except that the outer edges of all septa slope gradually toward the marginal shelf, not meeting the base at a sharp boundary. There is variation regarding septal face granulation. The septal faces of the holotype and paratypes from ALB-4911 all bear tall, blunt or Y-shaped granules that are not arranged in linear sequence. Septal faces of all other specimens examined are relatively smooth, bearing lines of very fine granules (7–9 μm in diameter) corresponding to the septal trabeculae. Upper, outer edges of larger septa, inward from the marginal shelf, bear a series of short, coarse trabecular spines, extending about 0.10 mm above the septum and covered by granules 35–40 μm in diameter (Plate 10b). S3 bifurcate in a complex but consistent pattern (Figure 2). Following the first bifurcation of an S3, the resultant S3I adjacent to an S2 is slightly longer than its counterpart adjacent to the S1, and bifurcates three times resulting in 4 septa. The shorter S3I adjacent to the S1 bifurcates six times, resulting in 7 septa. The final composition of a half-system is thus:S1, S3III, S3IV, S3IV, S3III, S3v, S3v, S3IV, S3II, S3IV, S3IV, S2, and the mirror image of this order for the complementary half-system in a system (Figure 2). Synapticulae are simple and, in an undamaged corallum, can usually be seen uniting the lower, outer septal edges, including those of the S1. Septal perforations occur sparingly at septal bifurcations and at bases of higher-order S3. Marginal shelf up to 3 mm wide but very delicate and often broken from corallum. All septa extend over the marginal shelf at a reduced height of about 0.6 mm but of the same septal width (i.e., about 0.12 mm thick).

Fossa deep, as in R. squiresi, enclosing an elongate, spongy columella aligned with the two principal S1. In some specimens (e.g., holotype; specimen from Mi Sake), the columella is a more solid fusion with several solid trabeculae aligned on the axis of the principal septa.
license
cc-by-nc-sa-3.0
bibliographic citation
Cairns, Stephen D. 1989. "A revision of the ahermatypic Scleractinia of the Philippine Islands and adjacent Waters, Part 1: Fungiacyathidae, Micrabaciidae, Turbinoliinae, Guyniidae, and Flabellidae." Smithsonian Contributions to Zoology. 1-136. https://doi.org/10.5479/si.00810282.486

Biology

provided by World Register of Marine Species
azooxanthellate
license
cc-by-4.0
copyright
WoRMS Editorial Board
bibliographic citation
van der Land, J. (ed). (2008). UNESCO-IOC Register of Marine Organisms (URMO).
contributor
Jacob van der Land [email]

Depth range

provided by World Register of Marine Species
390-804 m
license
cc-by-4.0
copyright
WoRMS Editorial Board
bibliographic citation
van der Land, J. (ed). (2008). UNESCO-IOC Register of Marine Organisms (URMO).
contributor
Cairns, Stephen [email]