Eugorgia Verrill, 1868

Breedy, Odalisca, Guzman, Hector M. & Vargas, Sergio, 2009, A revision of the genus Eugorgia Verrill, 1868 (Coelenterata: Octocorallia: Gorgoniidae), Zootaxa 2151, pp. 1-46 : 8-9

Genus Eugorgia Verrill, 1868

Lophogorgia (pars) Horn 1860: 233.

Gorgonia (pars) Verrill 1864: 33; 1866: 327.

Leptogorgia Verrill 1864: 32 .

Eugorgia (pars) Verrill, 1868a: 414.

Eugorgia Verrill, 1868: 406 –407; Studer 1887: 64 –65; Bielschowsky 1918: 39; 1929: 170; Kükenthal 1924: 343; Stiasny 1951:63, Bayer 1951: 99; 1981: 921.

Type species. Leptogorgia ampla Verrill, 1864 , by subsequent designation: Verrill 1868: 386.

Diagnosis. Gorgoniids branching mainly in multiple planes, lateral, partially dichotomous, or pinnatelike, often bushy. True neat dichotomy or pinnate branching rarely occur in this genus, but some species show close patterns: simple lateral branching and even dichotomous or pinnate sections, thus irregular branching, so these terms are used herein accordingly. Branch anastomosis absent. Axis horny, with a cross-chambered central core with a network of organic filaments frequently mineralized. ( Fig. 2 A–B). Holdfast attached to hard substrates or extending on muddy sediments. Polyps fully retractile into the coenenchyme, in slightly raised to prominent mounds arranged in series of longitudinal rows, or evenly distributed on the branches. Coenenchymal sclerites of various type: spindle, disc-spindle, capstan, and the most dominant form that defines the genus is the characteristic double disc. Anthocodial sclerites rarely found, usually flat rods and platelets with lobed margins, forming a weak points-like arrangements at base of the polyp tentacles. Colour of colonies and sclerites variable: colourless, yellow, orange, red, violet, brownish, or combinations of these.

Distribution. The genus is considered exclusively eastern Pacific (from southern California to Peru).

Species

Costa

Rica

Colombia Panama Nicaragua Peru Mexico Ecuador Salvador El USA

E. alba Acajutla Remarks. Verrill (1868a) divided the Panamic species of gorgoniids known at that time, into two groups: one included species having only warty “double-spindles” (obsolete term for spindle), and the other included species having “double-spindles”, and “double-wheels”. In his first group he included species of the genera Leptogorgia Milne Edwards and Haime, 1857 and what later became Pacifigorgia Bayer, 1951 ; and in the second, he included a mixture of species of Leptogorgia , and others later placed in Eugorgia and Pacifigorgia . Later on, Verrill (1868) established the genus Eugorgia for species in his second group that, besides having the double-wheel sclerites, are “with a distinctly granulose surface, owing to the large number of small naked spicula, the cells are mostly in two lateral bands”. However, the species of Leptogorgia and Pacifigorgia that he firstly included in the genus do not have double-wheel sclerites, and do not have a granulose surface. In 1868, Verrill redefined the genus Eugorgia including only the species with double-wheel (double discs) sclerites, and designated Leptogorgia ampla Verrill, 1864 as the type species. Eugorgia is presently considered an eastern Pacific genus; however, some Atlantic species of Leptogorgia are apparently related to it ( Bayer 1951, 1952). Bayer (1952) transferred Leptogorgia virgulata ( Lamarck, 1815) and three new species from the western Atlantic to Eugorgia based on the occurrence of disc-spindles and double discs in the coenenchyme. Since the external morphology of Leptogorgia and Eugorgia is very similar and the presence of disc-spindles and double discs is basically what made both genera different, it was a sensible decision. However, Bayer (1956, 1961) redefined the genus Leptogorgia to separate it from the monospecific genus Lophogorgia Milne Edwards & Haime,1857 on the basis of occurrence of symmetrical sclerites in the latter, and symmetrical and asymmetrical sclerites, “with flat tubercles fused into discs” in Leptogorgia . Thus, he transferred the four western Atlantic species to Leptogorgia again. Grasshoff (1988) in his revision of West African gorgoniid fauna found transitional forms between the two genera ( Lophogorgia and Leptogorgia ) and decided to synonymise both genera, so the four western Atlantic species with double discs remained in Leptogorgia . The southern African species Leptogorgia gilchristi ( Hickson, 1904) was described as Eugorgia by Hickson (1904) and as Eugorgia lineata by Thomson (1917), but since lineata and gilchristi are the same species, and sclerites are consistent with the Leptogorgia type ( Williams & Lindo 1997) instead of Eugorgia, Grasshoff (1992) established the new combination, Leptogorgia gilchristi , and synonymised both species.

Figures

FIGURE 2. Axis mineralization, SEM-micrograph of a longitudinal section of a terminal branch of Eugorgia multifida Verrill, 1868 (YPM 2257 b) after maceration in sodium hypochlorite; A, chambered core with mineralised filaments of CHAp; B, detail of CHAp microspheres coating organic filaments.