Squires's Cup Coral

Rhombopsammia squiresi Owens, 1986

Stephanophyllia formosissima var.—Alcock, 1902a:39–40.

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

Rhombopsammia waldmanae.—Squires, ms:13 [not published].

Rhombopsammia squiresi Owens, 1986a:250–252, figs. 1 a-d, 2a.

DESCRIPTION.—Corallum robust, up to 30.6 mm in calicular diameter (ALB-5513), with GCD:H ratios of 2.25–2.41. Base convex, basal angle as low as 127°. Costae of variable width depending on distance from epicenter and recency of origin. Central 6–8 mm of major costae bear a medial, unilinear series of coarse, rounded granules, each 0.08–0.10 mm in diameter (equivalent to the costal width). Beyond 8 mm from epicenter, costal granules become staggered or random in arrangement, and at the calicular edge (in the vicinity of the marginal shelf) the costae become poorly defined and rather porous. Costal arrangement and bifurcations similar to that of Stephanophyllia fungulus (Figure 3): 6 C1 originate at epicenter and eventually divide into 96 terminal costae. Intercostal width much greater than that of costae, 0.32–0.41 mm, and regularly traversed by synapticulae about 0.11 mm in diameter, producing a series of elliptical pores 0.15–0.25 mm in greater diameter.

Septa arranged in typical micrabaciid fashion: S1–2 non bifurcate, S3 having multiple bifurcations in a consistent pattern similar to that of S.fungulus (Figure 3), resulting in 96 septa. S1 composed of up to 60 fine, closely spaced trabeculae alternating in expression on each side of the septum, the alternation giving the septum a sinuous margin. Inner edges of S1 vertical; upper edges rounded; outer edges vertical to slightly undercut, producing a sharp boundary with marginal shelf. The 2 principal S1 are slightly smaller than 4 lateral S1 S2 similar in shape to S1, sometimes extending inward from the delta as a short lamella or series of 3 or 4 coarse spines. S3 very short, less than 1 mm, serving mainly as a point of origin for the S3I S3I about 2.5 mm long and are the tallest of the septa, originating relatively close to the S2-S3 delta. Septal faces covered by low triangular granules (8–10 μm in height) aligned in discontinuous, slightly elevated rows following the trabeculae. All septal edges are entire, without septal spines. Synapticulae extremely reduced, only visible in a broken corallum at the lower, outer septal edges of the terminal S3 bifurcations. Septal perforations present but rare and not arranged in a regular manner, occurring only at septal bifurcations and at the bases of higher order S3. Marginal shelf well developed, extending up to 3.5 mm beyond the lamellar septa. On marginal shelf, each septum, regardless of cycle, transforms from a thin lamella, about 0.10 mm thick, to a broad, flat, spongy mass about 0.75 mm wide, separated from one another by narrow septal furrows 0.22–0.25 mm wide.

Fossa deep, formed by the vertical inner edges of the S1, and S2-S3 deltas. Columella elongate in alignment with the 2 principal S1, composed of a mass of fused trabeculae.

azooxanthellate

622-1401 m