Truncatoflabellum formosum Cairns 1989

Truncatoflabellum formosum Cairns, 1989

Flabellum rubrum.—Yabe and Eguchi, 1942a:96–98 [in part: form A, pl. 8: figs. 16–19, 23, 24]; 1942b:131–132 [in part: Soyo Maru-107, 540, pl. 11: fig. 14].

Truncatoflabellum formosum Cairns, 1989a:69–70, pl. 35: figs. j,k; pl. 36: figs. a,b.—Cairns and Keller, 1993:265, figs. 101, 11A.

Truncatoflabellum n. sp.: Cairns, 1989a:73, pl. 38: figs. g,h.

DESCRIPTION.—Corallum compressed, the convex thecal faces meeting in rounded thecal edges. Angle of thecal edges, 37°–48°; inclination of thecal faces, 18°–25°. Largest specimen known (anthocyathus from TM (CR79-18)) 26.7 × 14.5 mm in calicular diameter and 28.9 mm in height, having a basal scar of only 3.3 × 4.6 mm. Two pairs of edge spines usually present, the lower pair cylindrical in cross section and pointed downward, the upper pair much more broadly based and oriented perpendicular to theca. GCD:LCD = 1.42–1.85. Theca reddish brown to white, bearing very fine transverse (not chevron-shaped) epithecal corrugations. Inside calice, 1–2 mm below calicular edge, theca adjacent to each of the 20 primary septa is lightly pigmented against a white background, giving the impression of a circumferential band within the theca. Calicular margin smooth.

Septa arranged in 3 distinct size classes in all specimens examined regardless of calicular diameter, accordingly: 20:20:40 (80 total septa). Primary septa nonexsert, their upper, outer margins meeting the thecal wall in a broad, graceful arch. Inner edges of primary septa vertical and slightly sinuous, merging with the columella. Secondary septa half to two-thirds width of primaries, their inner edges less sinuous and not attaining the columella. Tertiary septa only one-quarter to one-third width of a secondary. Fossa deep and narrow, containing an elongate, solid columella formed from fusion of lower, inner edges of 20 primary septa.

Truncatoflabellum formosum

Flabellum rubrum.—Faustino, 1927:53 [in part: ALB–5265,5658].—Yabe and Eguchi, 1942a:96–98 [in part: pl. 8: fig. 14].

DESCRIPTION.—Angle of rounded thecal edges 37°–43°, although in the large specimen from ALB–4314, the thecal edges are crested above the second pair of thecal spines. Inclination of convex thecal faces 18°–21°. Near base of corallum, thecal faces slightly more compressed, having more acute thecal edges. Largest anthocyathus examined (ALB–5289) 23.0 × 13.4 mm in calicular diameter and 31.4 mm tall; holotype (ALB–5249) 19.8 × 11.8 mm in calicular diameter and 21.4 mm tall. One or two pair(s) of spines occur(s) on thecal edges of anthocyathus. Lower pair of spines cylindrical, about 1.3 mm in basal diameter, and 2–3 mm above basal scar. Upper pair, if present, has a wider triangular base about 2.7 mm in greater diameter, which occurs 5–7 mm above basal scar (almost midway on thecal edge of a large specimen). Basal scar 4.5–5.5 × 2.8–3.1 mm in diameter; 12 complete septa originate from scar, despite nonhexameral symmetry of septa. Anthocaulus stage unknown. Theca usually slightly encrusted with serpulids, bivalves, and calcareous algae, but nonetheless usually smooth; theca marked by fine, white, longitudinal costal striae and equally fine transverse epithecal corrugations. Theca light reddish brown. Calice elliptical, GCD: LCD = 1.42–1.85.

Septa of most specimens examined arranged in three size classes: 20 primary, 20 secondary, and 38–40 tertiary septa, resulting in a total of 78–80 septa. Below a greater calicular diameter of 20 mm, pairs of tertiary septa are often missing. Primary septa slightly exsert in small specimens but attenuate in larger specimens, meeting the thecal edge in a graceful concave arch (Plate 35k). Secondary septa always nonexsert and about half the width of primary septa. Tertiary septa quite small, only to width of secondary septa. Lower, inner edges of primary septa conspicuously sinuous. Septa covered by blunt granules about 0.1 mm tall, regularly aligned in oblique rows along septal undulations.

Fossa deep. Columella rudimentary, composed of the fusion of the lower inner edges of primary septa.

DISTRIBUTION.—Recent: Korea Strait (Yabe and Eguchi, 1942a); Philippines (off Manila, Luzon; Leyte Gulf; Davao Gulf; Sulu Archipelago); Teluk Bone, Celebes; 37–933 m; 5.1°–17.8°C.

47. Truncatoflabellum candeanum (Milne Edwards and Haime, 1848), new combination

Flabellum candeanum Milne Edwards and Haime, 1848:278, pl. 8: fig. 13; 1857:95–96.—Marenzeller, 1889:46–48.

Flabellum elegans Milne Edwards and Haime, 1848:277.

Not Flabellum candeanum.—Duncan, 1870:300, pl. 20: figs. 1a–d [= undescribed species].—Tenison–Woods, 1878b:311.

Flabellum rubrum.—Yabe and Eguchi, 1942a:96–98 [in part: pl. 8: figs. 13–15,21, 22].

Flabellum rubrum candeanum.—Yabe and Eguchi, 1942b: 133–134.

DESCRIPTION.—Angle of rounded thecal edges 50°–80°; inclination of convex thecal faces 30°–41°. Largest anthocyathus examined (holotype of F. elegans) 32.3 × 16.5 mm in calicular diameter and 21.7 mm tall. Usually three pairs of thecal spines occur on anthocyathus, less commonly two pairs, but in one case four pairs. First pair of spines originates directly above basal scar, each spine up to 6 mm long, with a greater basal diameter of about 1.1 mm. Second pair massive, about 2.5 mm above basal scar, each spine up to 6 mm long with a greater basal diameter up to 2.3 mm. Third pair of spines smaller in diameter but longer, about 7 mm above basal scar, each spine up to 10 mm long, with a greater basal diameter of about 2.0 mm. Basal pair of spines directed downward, middle pair directed horizontally, and upper pair directed slightly upward. Basal scar 4.2–5.7 × 3.0–3.6 mm in diameter; approximately 20 complete septa originate from scar. Anthocaulus 4–5 mm tall at point of fracture, with a pedicel diameter of about 1.2 mm and a calicular diameter equal to that of anthocyathus basal scar. One pair of downward–projecting spines occur midway on thecal edge of anthocaulus. Before division, the fused anthocyathus and anthocaulus may be up to 7 mm tall, bearing a single pair of anthocaulus thecal spines and the basalmost pair of anthocyathus thecal spines. Anthocaulus contains 24 septa. Theca light reddish brown with slightly darker stripes corresponding to primary septa; specimens collected dead are occasionally bleached white. Theca usually not encrusted. Theca corresponding to primary septa often slightly raised, producing a slightly corrugated thecal face. Calice elliptical, GCD: LCD = 1.6–1.7. Upper thecal edge slightly scalloped, the apices of the margin corresponding to the primary septa.

Septa occur in three size classes, most commonly: 20 primary, 20 secondary, and 40 tertiary septa, resulting in 80 total septa. Number of primary septa, and thus total number of septa, roughly a function of greater calicular diameter, e.g., a corallum with a greater calicular diameter of 12 mm may have 16 primaries; 15 mm, 18 primaries; 16–18 mm, 20 primaries; 19 mm, 22 primaries; and 20–21 mm, 24 primaries. Primary septa moderately exsert, meeting the calicular edge at a right angle with no septal notch. Secondary septa slightly exsert, to size of primary septa. Tertiary septa not exsert and quite small, about to size of secondary septa. Inner edges of primary septa extremely sinuous and those of secondary septa also moderately sinuous. Tall pointed granules up to 0.15 mm high are aligned in rows perpendicular to septal edge. Lower, inner edges of primary septa bear large granules up to 0.25 mm tall.

Fossa relatively shallow. Columella robust, composed of a spongy trabecular mass bordered by lower, inner edges of primary septa.

Truncatoflabellum formosum est une espèce de coraux appartenant à la famille des Flabellidae.

azooxanthellate

42-933 m