Metafannyella lepidota (Bayer 1998)

“Fannyella lepidota, n. sp.
Figs. 26-31

Material Examined: Antarctic Peninsula: 64°50’S. 63°12’W, 155 fath. (=283 m), USS “Eastwind” sta. EW-66-006, 29 Jan 1966. 1 colony lacking holdfast USNM 58159 (SEM 1533). Fig. 31 top. –Vicinity of Joinville Island: 62°40’S, 54°45’W. 265 m USNS “Eltanin” sta. 1002, 15 Mar 1964. 2 colonies without holdfast USNM 83044 (SEM 1532). Fig. 31 bottom.

Scotia Sea: Between South Orkney and South Sandwich Is­lands: 61°38'S, 34°35’W, 3514-3495 m, USNS "Eltanin" sta. 1063, 6 Apr 1964. 2 colonies, one damaged and one lacking holdfast USNM 82958 (SEM 1508, 1510). Figs. 26a, 29. — Off South Orkney Islands: 60°51'S, 42°57’W, 284 m, USNS "Eltanin" sta. 1083, 14 Apr 1964. 4 incomplete colonies USNM 56660 (SEM 1511).

Ross Sea: 73°56'S, 178°56'W, 401-399 m, USNS "Eltanin" sta. 1931, 29 Jan 1967. 5 colonies and branches USNM 82959. —73°49'S, 178°13'W, 495-503 m, USNS "Eltanin" sta. 2021, 15 Jan 1968.7 colo­nies and branches USNM 82960. —73°51'S, 178°15'W, 485 m, USNS "Eltanin" sta. 2022, 15 Jan 1968. 1 colony with holdfast (holotype) USNM 82961, Figs. 26b, 27, 28, 30; and one lacking holdfast (paratype) USNM 82962 (SEM 1436, 1463, 1499, 1500). — 76°25'S, 170°24'W, 568 m, USNS "Eltanin" sta. 2075, 30 Jan 1968. 2 colonies lacking holdfast USNM 82963. — 75°50'S, 173°08W, 468-474 m, USNS "Eltanin" sta. 2080, 31 Jan 1968. 5 more or less complete colonies and fragments USNM 82964. —76°04'S, 164°46’W, 513-550 m, USNS "Eltanin" sta. 2095, 3 Feb 1968. 6 more or less damaged colonies (paratypes) USNM 82965 (SEM 1452). —76°08’W, 165°04’W, 494-498 m, USNS "Eltanin" sta. 2097, 4 Feb 1968. 4 incomplete colonies USNM 82966. —73°05'S, 180°00', 567 m, USNS "Eltanin" sta. 2119, 11 Feb 1968. 1 colony at­tached to scleractinian coral USNM 82967.

Etymology: Lepidotus, from Greek λεπτδωτος, scaly, from λεπτς, scale.

Diagnosis: Flabellate Fannyella of small size, more or less distinctly lyriform in aspect. Polyps about 1 mm tall, facing upward in spirals with a tendency to separate into whorls. Body scales in distinct longitudinal rows; abaxial body scales 7-8 in each row, moderately developed as ascus-scales, externally nearly smooth except for simple granules along proximal margin of exposed surface. Closed operculum coni­cal, partly obscured by circumoperculars. Opercular scales with thin apical keel. Swollen brood polyps covered by large, rounded, imbricating scales. Coenenchymal scales smooth, rounded, imbricated.

Description: The colonies (Fig. 26a, b) are dichoto­mously branched in one plane, producing uniplanar fans of small size, mostly about 10 cm tall, composed of slender, flex­ible branches up to 5 cm long and about 1 mm in diameter including the contracted polyps. The axis is dark brown with bronze metallic luster, its surface irregularly wrinkled and obscurely grooved longitudinally, fixed to the substrate by a small discoidal holdfast.

The polyps, about 1 mm tall or slightly more depending upon degree of contraction, are placed in irregular whorls or in open spirals around the branches (Figs. 27-29); when whorls are developed, 7-8 occur in 1 cm of branch length. Polyps containing planulae are conspicuously distended as a hemispherical brood chamber covered by smooth, oval, imbricating scales (Fig. 30 top).

The opercular scales (Fig. 31a-c) are lanceolate with a nearly transverse base, externally smooth except for some smooth granules arranged in irregular rows radiating outward from the vicinity of the nucleus; the central part of the inner surface has scattered, complex tubercles, and a thin, sharp longitudinal keel extends from the apex to near the nucleus. Some of the abaxial body sclerites are weakly modified as ascus-scales (Fig. 31d-h), externally almost smooth except for some simple granules localized along the curved, thickened ridge separating the exposed part of the sclerite from its tuberculate base embedded in the body wall and overlapped by the edge of the scale below; the proximal part of the inner surface (Fig. 31g) is covered by complex tubercles, the free distal margin smooth except for a few sharp radical crests that may or may not project as marginal dentations. The abaxial rows contain 7-8 scales, decreasing to 5-6 in the lateral rows and in the adaxial rows only 1-2 below the operculars. The coenchyme is covered by smooth, rounded imbricating scales (Fig. 31i), and the walls of the longitudinal stem canals contain small tuberculate, flattened ovals and rods (Fig 31i).

Distribution: Ross Sea; Scotia Sea.

Comparisons: Of the species with polyps arranged more or less in spirals, F. lepidota closely resembles F. mawsoni n.sp., which differs in the beaded radial ridges marking the exposed surface of the body scales (Fig. 36e-g) and the thick apical keel of the opercular scales, which is composed of several longitudinal crests (Fig. 36b, c). Well-developed colonies may superficially resemble small, lyrate colonies of F. kukenthali, which can be recognized by their cobblestone-like coenchyme (Fig. 41) and nearly smooth, thick body sclerites (Fig. 33). Specimens of kukenthali equivocal regarding these characters can usually be distinguished from lepidota by their opercular sclerites, which tend to be thick and tooth-like, with several more or less strongly serrate apical crests (Figs. 33a, 35a, 38a, 40a).

Remarks: Traditional sclerite preparation and/or examination of whole mounts by SEM may be necessary for accurate separation of F. lepidota from mawsoni, as the translucency of the body scales makes observation of the surface sculpture difficult.

Variations in the shape and spiculation of polyps occur among colonies from the same part of Antarctica (cf. Fig. 25 top, 25 bottom) as well as among colonies from widely separated localities (cf. Figs. 21, 25).

Although the depth of collection of the two colonies from sta. 1063 (USNM 82958) is unusually deep, they agree with this species in growth form and type of opercular sclerites. However, it is possible that they represent a different species as all other records of lepidota range from 400 to 568 m. Consequently, these two colonies are excluded from the type series of F. lepidota.”

(Bayer, 1998)