Comprehensive Description

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Description

2. Ophidiogorgia Bayer, 1980

 

FIGURE 3G–L

 

Ophidiogorgia Bayer, 1980:223–225; 1981b:934 [key to genus].—Bayer and Stefani, 1989:455.—Bayer, 1996b:179–180.

 

DIAGNOSIS. Colonies unbranched (flagelliform). Calyces arranged in whorls of up to 21, the polyp bases within a whorl often fused (Figure 3i); the strongly appressed calyces face upward. Operculum and distinctive marginals absent, all body wall scales being the same size and shape: small discoidal scales (Figure 3j–l). Body wall scales numerous but not arranged in longitudinal rows, except on young calyces, occurring as two imbricate layers on abaxial and lateral body walls, leaving a narrow strip on the adaxial face bare. Coenenchymal scales in two layers, including an inner layer of tuberculate spheroids that separate the stem canals. All sclerites have a coarsely granular outer surface.

 

DISCUSSION. Ophidiogorgia is distinctive among the primnoids in having several characters found in few, if any other, primnoid genera (Table 3): i.e., multilayered body wall sclerites, no operculum, and nonaligned body wall scales (except in juvenile calyces). Bayer (1996b) suggested that Ophidiogorgia may have evolved from Primnoella since they are morphologically similar: Primnoella has very reduced opercular scales, both genera have reduced adaxial sclerite coverage, and ontogenetically, Ophidiogorgia does have longitudinal rows of body wall scales in its early stages (Bayer, 1996b). Nonetheless, Ophidiogorgia differs in having fused basal calyces, more than eight marginal scales, granular sculpture on its body wall scales, and multiple layers of sclerites on the body wall and coenenchyme.

 

DISTRIBUTION. Antarctic waters: Bouvet Island, South Orkney, continental Antarctica, 27–426 m.

 

TYPE SPECIES. O. paradoxa Bayer, 1980, by original designation. The holotype is deposited at the USNM (58165).”

 

(Bayer and Cairns, 2009)

 

(Bayer, 1980)

 

 

Ophidiogorgia gen. nov.

 

Diagnosis.—Unbranched primnoids with polyps in regular whorls. Polyps tall, cylindrical, directed upward and appressed to coenenchyme but not adnate, covered abaxially and laterally with a multiple layer of circular platelets showing no trace of alignment in rows: adaxial side completely naked except for scales immediately surrounding the calicular aperture; scales folding inward around aperture but not differentiated as an opercu­lum: tentacles without sclerites. Coenenchyme thick, outer layer filled with sclerites like.those of polyps, inner layer containing stem canals separated by longitudinal tracts of tuberculate spheroids. mesogloea between inner and outer layers permeated by small solenia but lacking sclerites.

 

Type-species. Ophidiogorgia paradoxa, sp. nov.. here designated.

 

Distribution.—South Orkney Islands.

 

Etymology.—Greek ophidion, diminutive of ophis, serpent, + gorgia, in reference to the elongated, sinuous polyps. Gender feminine.

 

Remarks.—This genus is exceptional in several ways: (1) the absence of any indication of alignment of body sclerites in longitudinal rows in the fully developed polyps: (2) the tuberculate, pebble-like circular platelets scarcely differentiated as scales and deployed in a multiple layer; and (3) lack of specialization of the distalmost scales as an operculum. It grossly resembles the genus Primnoella and probably is most closely related to it. The irregular arrangement of the sclerites in the fully developed polyps can he interpreted as a derived character, as is the case in Primnoeides, because the scales of the young polyps in intercalary whorls retain traces of orderly rows (Fig. 8), which quickly become disrupted by addition of new sclerites as growth proceeds. As the polyps of Ophidiogorgia are adaxially naked, the genus must have arisen from a Primnoella-like precursor that already had lost its adaxial sclerites.”

 

 

(Bayer, 1980)

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Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

© National Museum of Natural History, Smithsonian Institution

Source: Antarctic Invertebrates Website (NMNH)

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