Smithsonian National Museum of Natural History

Original Description
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Diagnosis

Colony developing from encrusting patches, forming erect, unilaminar sheets , delicate and folded. Frontal wall of autozooids with inferred cryptocystidean de­velopment ; bordered by small areolar pores. Vertical walls with recessed septula, pierced by few pores. Primary orifice with prominent, blunt, lateral condyles, pro­ximal border with a low lyrula. A single adventitous avicularium present medio­proximal to orifice, perpendicular to frontal plane, facing laterally, with sharply hooked rostrum. Additional avicularia developed along margins of autozooids. Ovicell hyperstomial, spherical, budded from distal wall of brooding autozooid and recumbent on proximal frontal wall of succeeding autozooid ; smooth, imperforate except for two or three small pores close to aperture, developing a sutured ooecial cover. No spines.

Type species : Rhamphostomella bassleri Rogick. 1956.

Discussion

R. bassleri Rogick (Fig. 4 A, B) is incorrectly placed in Rhamphostomella Lorenz, a northern hemisphere genus, with a circumpolar distribution, all species of which display umbonuloid frontal wall ontogeny. It is properly a member of the Smitti­nidae, but its prominent, perpendicular suboral avicularium (reminiscent of that characterizing species of the genus Rhynchozoon Hincks), and the form of the ovicell, preclude its inclusion in any presently recognized genus. It is consequently here designated type species of the new genus, Rhamphosmittina.

Geographical distribution

Rogick (1956) described R. bassleri from two widely separate localities ; Mar­guerite Bay, Graham Land, and Queen Mary Land (65° 25' S, 101° 13' E). The six samples reported here are from equally widespread localities, suggesting that the species is widely distributed in Antarctic waters. Four samples originate from the Ross Sea ("Terra Nova" stns. 295, 339 ; "Discovery" stns. 1652, 1660), another from the Palmer Archipelago ("Discovery" stn. 190), and the most northerly from Shag Rocks, South Georgia ("Discovery" stn. 160)." (Hayward and Thorpe, 1988: 288-9)