Flabellum (Flabellum) politum Cairns 1989

Flabellum (Flabellum) politum

Flabellum patens Moseley, 1881:172 [in part: 1 of 7 syntypes].

Flabellum pavoninum var. distinctum.—Gerth, 1921:401.

Flabellum pavoninum.—Faustino, 1927:46 [in part: ALB-5178, 5217, 5311, 5212].

Flabellum paripavoninum.—Faustino, 1927:47 [in part: ALB-5212, 5311, 5527, 5312, 5392].

Flabellum pavoninum paripavoninum.—Yabe and Eguchi, 1942a:91–93 [in part: pl. 5: fig. 8a–c, Sôyô-maru 419, in part: specimen 1]; 1942b:129–130 [in part: pl. 11: fig. 9].

DESCRIPTION.—Angle of thecal edges 90°–136°, averaging 107°; inclination of lateral faces, 30°–45°. Coralla dense and relatively small, the largest specimen examined (ALB-5392) 36.1×22.0 mm in calicular diameter and 31.8 mm tall. Thecal faces meet in very acute thecal edges, which bear very low crests. Ratio of LEL:H = 0.46–0.78, the higher ratio corresponding to specimens with a low thecal edge angle. Thecal faces planar, sometimes with costal ribbing, but usually flat and smooth, almost porcelaneous. In large specimens with a fully intact calicular edge, the upper thecal faces are highly arched centrally, flanked by a shallow notch a short distance toward the thecal edge, followed by another small lobe nearer the calicular edge (Plate 28a,b). Thecal faces of some specimens, especially smaller specimens, sometimes have reddish brown stripes corresponding to the septa, but more often the coralla are uniformly white. Pedicel circular in cross section (1.0–1.4 mm in diameter), elongate (up to 5 mm), and invariably broken above the basal plate, clearly revealing the six protosepta. Ratio of GCD:LCD = 1.49–2.15, the higher ratios corresponding to specimens with long, intact pedicels and a low thecal edge angle. Ratio of GCD:H = 0.98–1.30, roughly equally wide as tall.

Septa hexamerally arranged in six cycles (192 septa) according to the formula: S1–3>S4>S5>S6. At a greater calicular diameter of 23 mm there are only five cycles; between 24–31 mm in greater calicular diameter progressively more pairs of S6 are added; and by a calicular diameter of over 31 mm most specimens have a full sixth cycle. Largest specimen examined has one pair of S7 (194 septa) in the space adjacent to a principal septum. S1–3 easily distinguished by their greater size and broad, sinuous inner septal edges (average SSI = 5.0), which fuse together to form the columella. Upper edges of S1–3 extend almost as high as calicular edge. S4 0.8–0.9 width of S1–3, slightly less sinuous, and do not attain the columella. S5 and S6 progressively less sinuous: S5 to size of S4; S6 rudimentary. Septal granules low and massive, about 0.07 mm tall.

Fossa elongate, deep, and narrow. Columella rudimentary.

Flabellum (F.) politum Cairns, 1989

Flabellum pavoninum paripavoninum.—Yabe and Eguchi, 1942a:91–93 [in part: Soyo Maru-419, pl. 5: fig. 8a–c]; 1942b: 129–130 [in part: pl. 11: fig. 9a–c].

Flabellum politum Cairns, 1989a:53–54, pl. 28: figs. a–f [synonymy].

azooxanthellate

40-402 m