Osthimosia multifaria, 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 : 2327

Osthimosia multifaria sp. nov.

( Figure 31C–E )

Material

Holotype. NMNH 1154045 : Eltanin cruise 5, station 219, 55 ◦ 47’ to 55 ◦ 52’ S, 66 ◦ 17’ to 66 ◦ 24’ W, 115 m, 23 September 1962; a tiny clavate colony, 0.37 mm long.

Description

Holotype colony shortly clavate, formerly encrusting an unknown erect substratum (hydroid?). Autozooids closely packed, with various orientations, visible portions of frontal shields smoothly calcified; with numerous closely spaced marginal pores. Primary orifice as wide as long, a U-shaped sinus constituting about one-quarter total length and occupying one-third of proximal border, below large, round-edged condyles. Peristome erect, flared, not completely obscuring primary orifice in frontal view, incorporating medio-proximally a tall, curving avicularian cystid, with apical rostrum directed proximo-laterally; rostrum acute to plane of orifice, 0.11 mm long, elongate oval, lacking a palate, thick crossbar with a stout median columella. Ovicell hyperstomial, spherical. 0.31 mm diameter, not enclosed by peristome; smoothly calcified, ectooecium with an extensive membranous frontal area, exposed entooecium with a few indistinct marginal pores. Vicarious avicularia frequent; largest type with a tumid cystid bordered by large marginal pores, the rostrum 0.62 mm long, spathulate and deeply cupped distally, lacking palate, crossbar stout, without columella; smaller type with asymmetrically spathulate rostrum, 0.18 mm long, curved to left or right, palate with just a small foramen distal and proximal to the thick crossbar, which has a stout columella.

Etymology

Latin, multifarius: various, with reference to the several different types of avicularia.

Remarks

The larger type of vicarious avicularium seen in O. multifaria is very similar to that of the Antarctic species O. malingae Hayward, 1992 , which also occurs on erect substrata but develops robust cylinders up to 40 mm long. The orifice of O. malingae is much larger than that of O. multifaria , with a proportionately shorter, broader sinus and more angular condyles, and whereas the peristome incorporates a medio-proximal avicularium, its rostrum is directed proximally, rather than proximo-laterally, as in O. multifaria sp. nov.

Figures

Figure 31. (A,B) Osthimosia minuscula sp. nov., Paratype. (A) Portion of colony showing morphology of peristome and ovicell; (B) detail to show primary orifice. (C–E) Osthimosia multifaria sp. nov., Holotype. (C) Portion of colony with columnar peristomial avicularia, ovicell and large vicarious avicularium; (D) detail showing primary orifice, ovicell and peristomial avicularia; (E) smaller vicarious avicularium, with asymmetric rostrum. Scale bars: 0.15 mm (A), 0.025 mm (B), 0.25 mm (C), 0.2 mm (D), 0.1 mm (E).