Fungiacyathus (Bathyactis) turbinolioides Cairns 1989

Fungiacyathus (Bathyactis) turbinolioides

DESCRIPTION.—Corallum robust, up to 10.3 mm in calicular diameter; holotype (best-preserved specimen) 8.1 mm in calicular diameter. Base flat to slightly convex, the central to of base relatively smooth. Peripherally, starting at a well-defined boundary, the base bears rounded equal costae 0.25–0.30 mm in width, separated by deep intercostal furrows about 0.20 mm wide. The costae bear low, rounded granules (0.1 mm in diameter) adjacent to the boundary area; taller and more slender cylindrical granules up to 0.07 mm tall near calicular edge (Plate 6e). In the central, relatively smooth area of the base, septal granules are somewhat masked.

Septa hexamerally arranged in four complete cycles. S1 composed of 5–8 tall, robust, compound trabecular spines, bordered by a low peripheral lobe of 5–9 smaller simple trabeculae. Each compound spine composed of 2 or 3 trabeculae, the third or fourth spine from the columella being the tallest. Compound trabecular spines about 0.35 mm broad project about 0.65 mm beyond septal edge. S2 shaped like the S1 except that the second or third trabecular spine is curved inward toward the columella. S3 also composed of 5 or 6 large, compound trabecular spines, bordered peripherally by a small septal lobe. The second to third S3 spine at the S3–4 junction are usually the tallest of all septal spines. S4 composed of 5–9 simple trabecular spines, equivalent in position and shape to the outer septal lobes of the lower-cycle septa. Septa planar, the septal spines, and upper septal edges covered by low parallel serrate ridges, which degenerate into discontinuous ridges and individualized clavate spines lower on septal face. Septal teeth triangular to cylindrical, often bifid, about 0.06 mm tall. Septal canopies not present, the higher-cycle septa joined to lower-cycle septa by thin digitiform processes. Synapticular plates T-shaped to solid, 3 or 4 per S1, the tallest one being the second from the columella and only half as high as the adjacent S4.

Fossa slightly concave, containing a robust columella composed of a low, solid fusion of 5–10 papillae.

azooxanthellate

600-930 m

slope