Smittoidea cancellata, 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 : 2308-2310

Smittoidea cancellata sp. nov.

( Figure 23 )

Material

Holotype. NMNH 1154053 : Eltanin cruise 9, station 740, 56 ◦ 06’ to 56 ◦ 07’ S, 66 ◦ 19’ to 66 ◦ 30’ W, 494– 384 m, 18 September 1963; one fragment.

Paratypes. VMNH 01367.200 : same data as holotype; seven fragments .

Description

Colony architecture unknown; type material consists of flat or curled, unilaminar flakes, with no evidence of substratum, basal walls of autozooids clean. Autozooids hexagonal, flat; frontal shield flat, or just convex medially, with thin, dimpled calcification, bordered by projecting vertical walls, and large, closely spaced marginal pores. Primary orifice wider than long, proximal edge with broad, straight-edged lyrula, occupying two-thirds of total width; condyles conspicuous, sharply pointed, down-curved. No oral spines. Peristome thin, low, with medio-proximal notch, above a small, oval suboral avicularium, with semi-elliptical mandible, parallel to frontal plane, directed proximally, crossbar slender with thin median columella. Sporadically, the avicularium is dimorphic, with scaphoid rostrum, ca 0.4 mm long, proximally directed. Ovicell recumbent on frontal shield of distally succeeding autozooid, hemispherical, ectooecium with large, uncalcified frontal area, the exposed entooecium pierced by numerous, irregularly shaped pores.

Measurements

For all measurements n = 20, mean ± SD: autozooid length 1.24 ± 0.11 mm; autozooid width 0.18 ± 0.01 mm; orifice width 0.25 ± 0.01.

Etymology

Latin, cancellatus: latticed, with reference to the dimpled calcification. Remarks

Species of Smittoidea have been described from shelf-sea environments worldwide, including Antarctica and the subantarctic southwest Atlantic. In its distinctive frontal calcification and small, oval, suboral avicularium S. cancellata sp. nov. is most similar to S. malleata Hayward and Thorpe, 1989 , reported from the South Shetland Islands, Graham Land and the Ross Sea, and S. albula Hayward and Taylor, 1984 , known only from the Ross Sea. However, both of these species have elongate oval ovicells, much larger than that of S. cancellata and more densely perforated. Smittoidea malleata is further distinguished in lacking a peristome, and in its lyrula, which is simply a short projection from the distal edge of the avicularium. The lyrula of S. albula is a conspicuous square structure, and a thin, raised peristome extends along the lateral borders of the orifice, and proximally incorporates the avicularium. In both of the described species the condyles are thick and angular, quite unlike the slender, pointed condyles of S. cancellata .

Figures

Figure 23. Smittoidea cancellata sp. nov., Paratype. (A) Group of autozooids, two with enlarged dimorphic avicularia; (B) detail of primary orifice; (C) ovicelled zooids. Scale bars: 0.25 mm (A, C), 0.1 mm (B).