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Description

4. Armadillogorgia Bayer, 1980

 

FIGURE 4A–G

 

Armadillogorgia Bayer, 1980:217; 1981b:934 [key to genus].—Bayer and Stefani, 1989:455 [key to genus].—Bayer, 1996a:527.

 

DIAGNOSIS. Colonies sparsely dichotomously branched. Calyces arranged in whorls of up to 20 calyces, facing upward in the holotype but downward in other specimens; adaxial side of calyces adnate to branch. Operculum not present nor are distinctive marginal scales; calycular aperture (mouth) a simple, unadorned pore (Figure 4b). Polyp completely covered by sclerites, the abaxial body wall covered by two rows of up to 70 broad, smooth, sickle-shaped sclerites that meet in an alternating (zigzag) pattern on calyx midline (Figure 4a, e). Sclerites on adaxial and circumoral region scale-like but not arranged in rows or in any order. Coenenchyme composed of two layers of sclerites, an outer layer of goblet-shaped sclerites (Figure 4f–g) and an inner layer of tuberculate spheroids.

 

DISCUSSION . Although Bayer (1980) compared Armadillogorgia to certain species of Primnoella, it is difficult to even consider its placement within the family Primnoidae. It lacks opercular and marginal scales, its body wall sclerites are not scales but a uniquely shaped sickle-like sclerite, its lateral and adaxial sclerites are not arranged in rows whereas the abaxial rows have up to 70 sclerites, and its sclerites do not demonstrate the characteristic cruciform extinction pattern under crossed Nicols. If this is a primnoid, it is a very highly derived genus.

 

DISTRIBUTION. South Georgia, Scotia Sea, 659–1,886 m.

 

TYPE SPECIES. A. cyathella Bayer, 1980, by original designation. The holotype is deposited at the USNM (58166).”

 

(Bayer and Cairns, 2009)

 

 

Armadillogorgia, gen. nov.

 

Diagnosis.—Dichotomously branched primnoids, axis stiff, brittle, cal­cified, without chambered core, holdfast spreading on solid substrate: pol­yps in whorls, closely appressed and adnate to stem, with 2 abaxial rows of numerous, closely fitting, narrow sclerites shaped like sickle blades set with the convex side outward and meeting at a zigzag suture line along the smoothly rounded middle of the abaxial side, forming a glossy, tight-fitting armor; lateral sclerites not in regular rows, not like the abaxials and not scalelike but similar to those of coenenchyme; no differentiated operculum, calicular aperture surrounded by small, imbricated, serrate scales. Coenen­chyme thick, in 2 layers separated by solenia. inner layer filled with tuber­culate, spheroidal or irregular grains, outer with tuberculate spheroids hav­ing a smooth. goblet-shaped or foliate process directed outward.

 

Type-species.—Armadillogorgia cyathella, sp. nov., here designated.

 

Distribution.—South Georgia.

 

Etymology,.—The name alludes to the transverse abaxial sclerites of the polyps, which call to mind the band-like armor of the mammals called “ar­madillo”; Spanish. from Latin armatus., armed. Gender feminine.

 

Comparisons.—This genus is grossly similar to Primnoella but the ver­ticillate polyps are adnate to the stem except for the oral region, the scales surrounding the aperture are numerous and not modified as an 8-parted operculum, and the abaxial body sclerites are so extremely modified that they have lost the scalelike form retained in even the most strongly modified species of Primnoella.”

 

 

(Bayer, 1980)

 

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© National Museum of Natural History, Smithsonian Institution

Source: Antarctic Invertebrates Website (NMNH)

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