Flabellum cinctutum Cairns & Polonio, 2013, n. sp.

• Main Authors: Cairns, Stephen D., Polonio, Virginia
• Format: Text
• Language: unknown
• Published: Zenodo 2013
• Subjects: Biodiversity; Taxonomy; Animalia; Cnidaria; Anthozoa; Scleractinia; Flabellidae; Flabellum; Flabellum cinctutum; Antarctic; The Antarctic; Argentina; Fossa; Antarc*
• Online Access: https://dx.doi.org/10.5281/zenodo.6151619; https://zenodo.org/record/6151619

Flabellum cinctutum , n. sp. Figs. 4 C–F, 17 Description. The corallum is subcylindrical to ceratoid, the largest specimen (PAT 1208 DR 16) measuring 21.4 mm in CD (circular) and 42.3 mm in height. The holotype measures 18.7 x 19.4 mm in CD, 38.0 mm in height, and has a PD of 3.1 mm; however, the base of most specimens is slightly wider than the lower pedicel, up to 3.8 mm in diameter. The coralla are rarely straight, but usually bent or curved in an irregular fashion (scolecoid), often changing diameter abruptly, as though reacting to an injury, which may be the case because the theca is extremely thin and fragile. The entire theca is encircled by numerous (6–8 /mm), low, horizontal ridges; these ridges are straight, not rising to peaks at each costal insertion as in most flabellids. Small (0.1 mm in diameter), rounded granules are aligned on these ridges, giving the theca a slightly rough texture. The corallum is white and porcellaneous. The septa are hexamerally arranged in four complete cycles (48 septa) according to the formula: S 1– 2 >>S 3>S 4. The axial edges of the S 1–2 are straight and extend almost to the center of the calice, producing a very deep and narrow fossa. Their upper edges form a graceful concave arch as they approach the calicular edge, but completely attenuate about 2.5 mm from the calicular edge. There is no evidence of a pseudocolumella or fusion of the lower axial edges of the S 1–2. The S 3 are much smaller (only about 0.9 mm in width), their axial edges finely sinuous. The S 4 are smaller still (0.4–0.5 mm wide), almost rudimentary, and also have finely sinuous axial edges accompanied by small pointed spines. Remarks. Flabellum cinctutum resembles F. flexuosum Cairns, 1982 in corallum morphology, both species having fragile, irregularly shaped, ceratoid coralla. But, F. cinctutum differs in having only four cycles of septa ( F. flexuosum has five), straight axial edges of the S 1–2 (those of F. flexuosum are sinuous), and its theca is consistently ringed and granulated (the theca of F. flexuosum may be ringed but usually only on the lower half and in a chevron-shaped pattern, never having granules). Furthermore, F. flexuosum is known only from the Antarctic region, and generally at shallower depths (101–659 m). Distribution. Continental slope off central Argentina (Fig. 17), 500–1626 m. Material/ Types. Holotype: PAT0209DR 3, USNM 1193313. Paratypes: PAT0108DR 1, 6, MNCN 2.04/ 1113; PAT0108DR 7, 3, MNCN; PAT0108DR 15, 3, MNCN 2.04/ 1116, and 2, USNM 1193314 and 1193311; PAT 1008 DR 1, 6, MNCN; PAT 1008 DR 4, 2, MNCN; PAT 1108 DR 5, 2, MNCN; PAT 1108 DR 11, 1, MNCN 2.04/ 1115; PAT 1208 DR 7, 5, MNCN 2.04/ 1114; PAT 1208 DR 9, 1, MNCN; PAT 1208 DR 14, 1, MNCN; PAT 1208 DR 16, 1, MNHN; PAT0209DR 1,1,MNCN; PAT0209DR 3, 2, USNM 1193316; PAT0209DR 4, 7, MNCN, and 1, USNM 1193312; PAT0209DR 8, 4, MNCN; PAT0209DR 14, 2, MNCN 2.04/ 1117; PAT0209DR 15, 3, MNCN; PAT0210BC 19, 1, MNCN; WH 197 / 71, 1, USNM 83397. Type locality. 44.769 °S, 59.438 °W (continental slope off Cabo Raso, Argentina), 1513 m. Etymology. From the Latin cinctutus (meaning girded, enclosed, encircled as though by a belt or band), an allusion to the numerous, fine, granulated, horizontal epithecal bands that encircle the corallum. : Published as part of Cairns, Stephen D. & Polonio, Virginia, 2013, New records of deep-water Scleractinia off Argentina and the Falkland Islands in Zootaxa 3691 (1) , DOI: 10.11646/zootaxa.3691.1.2, http://zenodo.org/record/222205