Comprehensive DescriptionRead full entry
“Family Chrysogorgiidae Verrill
Chrysogorgidae Verrill, 1883: 21.
Chrysogorgiidae Versluys, 1902: 2. - Kükenthal, 1919: 486; 1924: 383. — Bayer, 1956: F216; 1974: 262.
Dasygorgidae Wright & Studer, 1889: xxxix.
Dasygorgiidae Hickson, 1904: 221.
Malacogorgiidae Hickson, 1904: 226.
Diagnosis. — Gorgonaceans having an unjointed scleroproteinous axis with a central core that is not hollow and cross-chambered, made up of concentric layers that are not undulated, with a smooth surface unmarked by longitudinal grooves (except on lower part of trunk in some cases). Axis branched or unbranched, arising from a rootlike or discoidal base that is usually strongly calcified. Sclerites usually present in coenenchyme, in the form of flat, oval or elongate scales with or without a median constriction and sometimes terminally lobate, and/or fusiform rods with prickly sculpture; scales showing irregular concentric bands of interference colors in polarized light. Axis more or less heavily calcified, commonly showing metallic or iridescent reflections.
Discussion. – Although this family has been considered to be generally one of deep waters, a few species from relatively shallow water have been known for a long time: Chrysogorgia cupressa (Wright & Studer), 90 m (Versluys, 1902); Trichogorgia flexilis Hickson, 102 m (Hickson, 1904); Trichogorgia capensis (Hickson), 46 m (Hickson, 1904); and Trichogorgia viola Deichmann, 79 m (Deichmann, 1936).
In 1972, the second author obtained a delicate, flabellate gorgonian by diving in the Fiji Islands, which proves to belong to a species of chrysogorgiid strikingly similar to one recently described from the Palau Islands (Bayer, 1974). Comparison of the two shows that they are distinct but related species that cannot be assigned to Trichogorgia because of differences in colonial form and branching. Therefore, we now propose a new genus, Stephanogorgia, for the species from Fiji, and transfer Trichogorgia faulkneri Bayer into it.
In addition, another gorgonian recently found among the octocorals collected by the U.S. Fish Commission steamer "Albatross" during its Philippine Cruise of 1907-1910 has proved to be a third species referable to the genus Stephanogorgia.
Coincidentally, Dr. Charles Birkeland of the Smithsonian Tropical Research Institute has sent us some specimens from the Atlantic coast of Panama that are referable to the original genus Trichogorgia, first described from South Africa (Hickson, 1904). These specimens are very similar to some dredged along the Caribbean coast of Central and South America by research vessels of the University of Miami. Comparison shows that all are the same, and that they represent a new western Atlantic species of Trichogorgia. It is entirely appropriate to record this new Atlantic Trichogorgia at the same time that we remove the first presumed Pacific representative from the genus. Therefore, the genus Trichogorgia remains unrepresented in the Pacific, as Chrysogorgia constricta Hiles, 1899, which was assigned by Hickson (1904: 221) to his new genus Trichogorgia, is probably not even a chrysogorgiid (Versluys, 1902). Although the type-specimen was re-examined by Hickson, the original figures of it are not convincing (Hiles, 1899: 195, pl. 22 figs. 8-10).
One of the major taxonomic characters used in classifying the Chrysogorgiidae is the branching and resultant growth form of the colony. We have received from South Africa specimens having distinctively chrysogorgiid sclerites and polyps, but differing in branching, which fit satisfactorily into no established chrysogorgiid genus. Rather than widening the generic definition of Chrysogorgia to accommodate these unusual specimens, we are here establishing a new genus for them.
The characteristics distinguishing the two new genera herein proposed are shown in the following key to the genera of Chrysogorgiidae.
Key to the genera of the family Chrysogorgiidae
1. Colonies unbranched: 2
1. Colonies branched: 3
2. Polyps with an operculum of 8 triangular plates: Chalcogorgia Bayer
2. Polyps without an operculum, but with the bases of the tentacles armed with several small sclerites: Radicipes Stearns
3. Colonies branched in one plane: 7
3. Colonies not branched in one plane: 4
4. Primary branches unbranched: Iridogorgia Verrill
4. Primary branches give rise to secondary branches: 5
5. Secondary branches repeatedly subdivided in apparently dichotomous manner: 6
5. Secondary branches bearing a few short lateral branchlets arise all around the main stem in "bottle brush" manner: Xenogorgia gen. nov.
6. Colonies with dichotomously divided branches arising from the upper end of a stout main trunk, monopodial: Metallogorgia Versluys
6. Colonies with dichotomously divided branches arising along the main stem in a regular or irregular spiral sequence, sympodial; one or more of the uppermost branches may divide in one plane and even dominate the colony so as to produce a flabellate or biflabellate form, but traces of the spirally arranged older branches usually can be observed on the lower parts of the main stem: Chrysogorgia Duchassaing & Michelotti
7. Branching unilateral, forming flat, lyrate colonies with few, long terminal branchlets reaching or surpassing half the height of the fully developed colony: 8
7. Branching pinnate, forming broad, flat fans with many relatively short branchlets much less than half the height of the fully developed colony: Stephanogorgia gen. nov.
8. Sclerites abundant, including many plates with thick projecting processes developed on the outer surface, as well as thin scales with serrated edges: Pleurogorgia Versluys
8. Sclerites few or absent; when present, consisting of small scales with slight median constriction ("double paddles") or without waist: Trichogorgia Hickson”
(Bayer & Muzik, 1976)