Truncatoflabellum dens (Alcock 1902)

Flabellum (Flabellum) dens Alcock, 1902

Flabellum dens Alcock, 1902a:32, pl. 4: figs. 30, 30a.—Faustino, 1927:59, pl. 4: figs. 6, 7.—Zibrowius, 1974:20.

DESCRIPTION.—Corallum small and highly compressed; inclination of lateral faces 14°–18°. Angle of rounded thecal edges changes abruptly at a height of 5–6 mm, changing from 58°–79° to 21°–35°. Alcock's (1902a) figured syntype 12.5 × 5.6 mm in calicular diameter and 15.7 mm tall, although another syntype (Plate 28j,k) is larger: 13.8 × 6.7 mm in calicular diameter and 22.5 mm tall, but is badly worn and damaged. Because of the relatively elongate corallum and low thecal edge angle, the LEL:H is consistently 0.92–0.93. Theca smooth and worn in syntype series. Pedicel usually broken, but, when present, 1.3–1.4 mm in diameter; transverse division not present. Ratio of GCD:LCD = 1.7–2.3; GCD:H = 0.68–0.82.

Septa hexamerally arranged in four cycles (48 septa) in smaller coralla. In larger coralla there are 20 primary septa, 20 secondary septa, and 8 or 9 pairs of tertiary septa, totaling 56–58 septa. S1–2 (or primary septa) equal in size; S3 (secondary septa) about half size of S1–2; S4 (tertiaries) are rudimentary. Inner edges of larger septa vertical and very sinuous, enclosing a deep and narrow fossa. Columella rudimentary.

azooxanthellate

286-555 m

slope