Scriblitopora sepicula, Hayward & Winston, 2011

Hayward, Peter J. & Winston, Judith E., 2011, Bryozoa collected by the United States Antarctic Research Program: new taxa and new records, Journal of Natural History 45 (37 - 38), pp. 2259-2338 : 2271-2274

Scriblitopora sepicula sp. nov.

( Figure 6 )

Material

Holotype. NMNH 1154050: Eltanin cruise 9, station 740, 56 ◦ 06’ to 56 ◦ 07’ S, 66 ◦ 19’ to 66 ◦ 30’ W, 494– 384 m, 18 September 1963; a small colony encrusting a fragment of Reteporella , partly overgrown by a colony of Hemismittoidea lanceolata sp. nov.

Description

Colony encrusting, unilaminar. Autozooids oval, separated by deep grooves. Frontal shield a flat cryptocyst, separated by a raised and crenulated mural rim from deep, sloping gymnocystal lateral walls. Cryptocyst finely granular; opesia distally situated, semicircular, occupying one-quarter total cryptocyst length; three pairs of large, irregular opesiules evenly spaced along lateral borders of cryptocyst. Gymnocystal lateral walls smooth, incorporating mural pore chambers, evident as large, uncalcified windows in the disto-lateral arc of the lateral walls. Stout, cylindrical spine bases rising from the lateral walls and projecting above the mural rim, 12 to 14 in number, evenly spaced around the entire periphery of the cryptocyst; all appear to have borne basally jointed spines, those around the proximal end of the cryptocyst are especially prominent, and show that the spines must have curved above the frontal membrane. Ovicell prominent, elongate oval, arising from the disto-lateral wall of the maternal zooid and inferred to have budded from the distalmost pore chamber; calcification smooth, imperforate, with a conspicuous longitudinal frontal suture, aperture with a pronounced rim, and lateral flaps, that overarch the opesia of the zooid. Closure of the ovicell was not apparent in the limited material to hand but, as the opesia is almost completely overarched, it is probable it is closed by the zooidal operculum.

Measurements

Cryptocyst length (including opesia): n = 4, 0.24 ± 0.01 mm (mean ± SD); cryptocyst width: n = 4, 0.19 ± 0.007 mm; opesia length: n = 5, 0.05 ± 0.002 mm; opesia width: n = 5, 0.10 ± 0.004 mm.

Etymology

Latin, sepicula : a fence, wall, with reference to the mural rim bounding the cryptocyst.

Remarks

The holotype material of this tiny and rather inconspicuous species is presently very limited, although further colonies may yet be found encrusting the abundant phidoloporid material recovered from Eltanin cruise 9, station 740. Species bearing multiple opesiules are known in the genera Micropora and Ophaeopora, and a minority of microporids bear few, small spines, apparently budded from the vertical walls at the distal end of the autozooid. However, in all of these the ovicell has a coarsely granular cryptocystal calcification, with gymnocystal calcification, when present, limited to a narrow band bordering the rim of the ovicell aperture, and the smoothly calcified ectooecial layer characteristic of the new genus does not seem to have been reported for any other microporid taxon. Most described species of Microporidae display polymorphism in the form of adventitious or interzooidal avicularia, and kenozooidal polymorphs are known for a few. The spines of S. sepicula are kenozooidal and the ovicell seems to be a polymorph, but no other polymorphic zooids are apparent in the holotype, although they may yet be found to occur when further material becomes available.

Superfamily CELLARIOIDEA Fleming, 1828 Family CELLARIIDAE Fleming, 1828

Cellaria megalodonta sp. nov.

( Figure 7 )

Material

Holotype. NMNH 1154032 : Eltanin cruise 35, station 2276, 33 ◦ 14.5’ S, 126 ◦ 20’ E, 183–192 m, 8 September 1968.

Description

Colony large and bushy, richly branched, 9.5 cm high. Internodes cylindrical, 5–6 mm long, 0.9 mm wide, straight, or slightly curved basally immediately above dichotomy, consisting of alternating whorls of five autozooids. Nodes initially formed by fracture, exposing internal bundle of about five chitinous tubes; subsequently reinforced by tangled bundle of fine chitinous tubes, appearing to bud from the proximalmost autozooids of the internode(s) distal to the node. Autozooids longer than wide, mostly diamond shaped, but narrowly hexagonal where the internode broadens to accommodate ovicells, clearly separated by thin, raised ridges. Frontal shield concave, finely granular. Opesia situated in distal half of autozooid, distant from distal edge of autozooid; about as wide as long, bordered by a thickened, crenulated rim, proximal edge straight but corners rounded. A pair of massive, laterally flattened and platelike denticles on each of proximal and distal borders of orifice, the tips of opposing pairs almost touching, those of the proximal pair curving frontally. Ovicelled autozooids in groups, marked by abrupt swelling of the internode, each ovicell apparent as a distinct frontal convexity in autozooids distal and disto-lateral to the brooding autozooid; ovicell aperture broad, partly occluded by a flat plate, leaving a narrow, crescentic opening. Vicarious avicularia sparsely distributed, as long as autozooid but twice as broad; the rostrum occupies distal half of cystid, its rim raised and smoothly curving, supporting a semicircular mandible that occupies almost entire breadth of cystid.

Measurements

For all measurements, n = 20, mean ± SD: autozooid length 0.48 ± 0.03 mm; autozooid width 0.31 ± 0.02 mm; opesia length 0.11 ± 0.01 mm; opesia width 0.11 ± 0.01 mm.

Etymology

Greek, megas: large; odontos: tooth, with reference to the paired massive denticles within the opesia.

Remarks

The genus Cellaria is extraordinarily speciose and occurs throughout the shelf seas of the world, with the apparent exception of the Arctic. There has been no comprehensive review of the genus. Many southern hemisphere species have been described and figured with SEM by Gordon (1984, 1986), Hayward (1995), Hayward and Thorpe (1989) and d’Hondt and Gordon (1999), and further descriptions, without the advantage of SEM, can be found in earlier literature. Although a few species have enlarged avicularia similar to those seen in C. megalodonta sp. nov., none of those described and figured in the literature cited here bears the huge opesial denticles seen in the latter.

Figures

Figure 6. Scriblitopora sepicula sp. nov., Holotype. (A) Part of the holotype colony; (B) detail of a single autozooid to show spine bases; (C) an ovicelled zooid. Scale bars: 0.25 mm (A), 0.10 mm (B), 0.15 mm (C).

Figure 7. Cellaria megalodonta sp. nov., Holotype. (A) Part of an internode with ovicelled zooids; (B) detail of autozooids; (C) detail to show vicarious avicularium, the distal rim of the rostrum damaged. Scale bars: 0.1 mm.