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Classification


USNM 17628

Geographic Distribution

Antarctic Convergence illustration Antarctic convergence

Osthimosia notialis   Species

Synonymy

Original Description
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Original Description
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"Osthimosia notialis sp. nov.
Plate Vg, VIa,b

Material

HOLOTYPE: BMNH 1990.7.31.9., National Antarctic Expedition, Ross Sea

PA RATYPES: BMNH 1990.7.31.10., 'Discovery' Stn 42.

Other material: 'Discovery' Stns 167, 190, 371, 1872. National Antarctic Expedition, Ross Sea, March 1903, 3.6.1903, 6.12.1903. British Antarctic Survey, Signy Island, Normanna, E. of Outer Is., 21.2.1986

Description

Colony forming small pisiform growths, 2-4 mm diameter, slender cylinders up to 10 mm long, or small, encrusting domes; most frequently on erect substrata including other bryozoans, cnidarians or sponge spicules. Autozooids with distinct boundaries; with convex, finely nodular frontal wall bordered by few, large, marginal pores. Primary orifice slightly longer than wide, with a deep, U-shaped proximal sinus comprising one-third its total length; condyles thickened and prominent. Peristome high, typically with well-developed lateral lobes, incorporating medio­proximally a single, relatively large, suboral avicularium with oval rostrum, proximally directed. Vicarious avicularia frequent, as long as autozooids; rostrum narrow, parallel-sided proximally, abruptly expanded to a slender spoon shape distally; palate with extensive foramen; crossbar slender, without a columella. Ovicell spherical, prominent, smooth-surfaced, with a broadly triangular area of smooth entooecium exposed frontally.

Measurements (mm) S.D.
Orifice length 20 0.15 0.005
Orifice width 20 0.13 0.005

Remarks

Osthimosia notialis is distinguished from other Antarctic and sub-Antarctic species of Osthimosia by its relatively large, proximally directed, suboral avicularium, its slender vicarious avicularia, and by the ovicell, which has a relatively larger frontal fenestra than in other species. This rather inconspicuous species is perhaps widely distributed in Antarctic waters; the present material is from localities as far apart as South Georgia and the Ross Sea." (Hayward, 1992: 295-7)

Geographic Distribution

Ross Sea; Signy Island, Normanna, E. of Outer Islands; South Georgia

Specimens

Type Status Catalog No. Date Collected Location Coordinates Depth (m) Vessel
  17628 Images Available 4/23/1971 South Atlantic Ocean 54.8° S, 65.3° W   Hero R/V

View additional taxa  View all species collected at same locations as Osthimosia notialis