Fenestrulina asperula, 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 : 2313-2314

Fenestrulina asperula sp. nov.

( Figure 25C, D )

Material

Holotype. NMNH 1154037 : 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 piece of gravel.

Description

Colony encrusting, unilaminar. Autozooids oval to hexagonal, steeply convex frontally and separated by deep grooves. Primary orifice slightly wider than long, with straight proximal edge, occupying about one-sixth total autozooid length; six basally jointed spines evenly spaced around lateral and distal borders of orifice, four in ovicelled zooids. Ascopore immediately proximal to orifice, the distance between its distal rim and the proximal orifice edge equivalent to about one-half orifice length; irregularly oval, slightly recessed into frontal shield, its inner rim often notched distally. Frontal shield of autozooid finely granular, but with sporadic irregular ridges, typically developing a ridged, knobbly border encircling the ascopore; pores few in number, irregularly stellate, two proximo-lateral to the orifice, on each side, others closely spaced around distal border of autozooid, and more widely spaced, and indistinct, around lateral and proximal borders. A sharp boundary evident between the cryptocystal calcification of the frontal shield and the gymnocystal calcification of the vertical walls. Ovicell longer than wide, prominent; ectooecium almost entirely membranous, but forming a thin rim around the basal periphery of the ovicell, continuous with a thin lip around its aperture; entooecium smoothy calcified, ridged and knobbly, with indistinct marginal pores.

Measurements

For all measurements n = 10, mean ± SD: autozooid length 0.63 ± 0.05 mm; autozooid width 0.46 ± 0.08 mm; orifice length 0.09 ± 0.01 mm; orifice width 0.15 ± 0.01 mm.

Etymology

Latin, asperula : uneven, with reference to the irregularly ridged frontal calcification.

Remarks

Species of Fenestrulina have been described from shelf environments worldwide, and the genus seems to be especially richly represented in Antarctica and the subantarctic southwest Atlantic. All species presently known from these regions have been described and figured by Hayward (1995) and Hayward and Ryland (1990), a total of 15, and F. asperula differs from all of them in its sparsely developed, irregularly shaped pores and in its proportionately large, oval ascopore. The elongate oval ovicell, with its irregular ridges, recalls that of the Antarctic species F. proxima ( Waters, 1904) but in that species the ascopore is tiny, crescent-shaped and situated close to the proximal edge of the orifice, and the pores bordering the frontal shield are large, round and numerous.

Figures

Figure 25. (A, B) Fenestrulina specca. (A) Group of autozooids; (B) ovicelled zooids. (C,D) Fenestrulina asperula. (C) Ovicelled zooids; (D) a single autozooid at the colony margin. Scale bars: 0.25 mm (A, B, C), 0.1 mm (D).