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Classification


Chondriovelum   Genus

Synonymy

Original Description
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"Chondriovelum gen. nov.

Diagnosis

Colony encrusting or erect. Autozooids with depressed cryptocyst extending be­neath frontal membrane for greater part of its length. Cryptocyst with reflected distal lip, and lateral opesiular indentations, extending distally as a thin ridge de­limiting the opesia. Avicularia vicarious, as large as autozooids, with distal groove for reception of the tip of the mandible ; with complete granular cryptocyst pierced by small opesiular foramina in separate distal and proximal groups. Mandible symmetrical, with thickened longitudinal sclerites, fusing to form a central rachis distally, and membranous lateral expansions. Ovicells assumed not to occur.

Type species : Labioporella adeliensis Livingstone, 1928.

Discussion

The tropical genus Labioporella Harmer is characterized by an extensive, porous cryptocyst, continuous distally with a calcified, basally directed tube which partly encloses the retracted polypide of the autozooid. It has large vicarious avicularia, each with a well developed cryptocyst and a polypide - tube homologue, and supporting a rounded mandible (Cook 1964). L. adeliensis Livingstone (Fig. 1A, B), in contrast, has an extensive, imperforate cryptocyst, reflected distally and not de­veloping a polypide tube (Fig. 1A). The vicarious avicularia of L. adeliensis have an almost complete cryptocyst, and symmetrical, winged mandibles with a slender distal portion. Livingstone's species is more properly assigned to the Onychocelli­dae than to the Labioporellidae (Cook 1964), and in its symmetrical, bimembranous avicularian mandible is most similar to species of Smittipora Jullien. It differs from all species of that genus, however, in its more complete development of cryp­tocystal calcification, particularly in the case of the avicularia, which in Smittipora have a substantial opesium. Further, the avicularian cystid in Smittipora is rounded distally, lacking the curving, distal groove, for accommodating the rachis, which is seen in L. adeliensis. These differences are sufficient to separate Livingstone's species at the generic level, and it is accordingly denoted as type species of a new genus, Chondriovelum.

Chondriovelum adeliense (Livingstone) forms erect, slender, branching, bilami­nate colonies, each rising from an encrusting base. Autozooids and avicularia are thickly calcified, with deeply depressed, granular cryptocysts, and distinctly beaded mural rims. Smittipora angustiloba Moyano is strikingly similar to C. adeliense, most particularly in its granular calcification and in the almost complete avicularian cryptocyst (Fig. 1C). It is here formally reassigned to Chondriovelum. C. angustiloba forms thickened encrusting patches on hard substrata.

Geographical distribution

Chondriovelum adeliense appears to be an endemic Antarctic species. It was described by Livingstone (1928) from three stations off Queen Mary Land (92° -97° E), and by Androsova (1972) from six localities on the coast of Australian Antarctic Territory between 63° E and 167° E. The present material is from Dis­covery stn. 190, Bismarck Strait, Palmer Archipelago (64° 56' S, 65°35' W, 315 m). Chondriovelum angustiloba (Moyano) was originally described from Tierra del Fuego. "Discovery" samples originated from two stations, off Cape Horn (56° 19.5' S, 67° 10' W, 121 m), and from the Patagonian Shelf ( 54°S, 64° 57.5'W, 118 m). It does not seem likely to occur in Antarctic seas." (Hayward and Thorpe, 1988: 278-80)

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