Eugorgia excelsa 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 : 20-22

Eugorgia excelsa Verrill, 1868

Figure 9 , Plate 5A–C

Eugorgia nobilis var. excelsa Verrill, 1868: 409 ; 1870: 553–554; Bielschowsky 1929: 176; Kükenthal 1924: 344; Stiasny 1951: 65; Harden 1979:127 –128.

Material examined. Syntype series: YPM 401, dry, La Paz, 11–15 m, W.B. Rich, no date; YPM 1710, dry, Acapulco, no depth given, A. Agassiz, 1859–1860; YPM 4052, a–d, 8716, a–b, 8717, a–b, 8718, a–f, 8719, a–c, 8720, a–f, 8721, 8722, 8723, 8724, 8725, 8902, MCZ 36316 (donor YPM), USNM 44148, USNM 33601 (fragment of YPM 4052, donor A.E. Verrill), dry, La Paz, 11–15 m, J. Pedersen, no date.

Other material: MEXICO: Gorgonia-6, dry, Islas Gringas, Guaymas, 10–15 m, J.L. Carballo, 27 November 2002; MNHN oct.0000-0550, dry fragments, La Paz, no depth given, M. Diguet, 1913.

Description. Colonies are large and flabelliform, mostly wider than high. Examined specimens measure up to 65 cm in height, and 85 cm in width. Branching is profuse, irregular and dichotomous (Plate 5A). Holdfasts are large, spreading and thick, in some colonies having a 1 cm thick layer of gorgonin deposited on the substrate. Holdfasts cover rocks and shells. In some colonies a thick stem, up to 3 cm in diameter, and 20–22 cm long arises from the holdfast and then branches, but generally several thick stems arise directly from the holdfast branching close to the base. Branches compressed at the base, 5–8 mm in diameter, more cylindrical, and tapered at the ends, 2–3 mm in diameter, with blunt or rounded tips, about 1–2 mm in diameter. Unbranched final twigs reach up to 10 cm in length. Some colonies present tumour-like growths on the branches that are covered by coenenchyme producing lumpy branches (Plate 5B). Full grown colonies have thicker branches and thinner branchlets, and the branching is more irregular and profuse. Colonies are dark reddish brown, varying somewhat in hue in different specimens, only YPM 1710 shows a purplish colour (Plate 5A–B). Marked longitudinal grooves occur along the thick branches, and near the base. The polyps are evenly distributed all around the branches, crowding the surface, and the polyp-apertures are small, up to 0.5 mm in diameter (Plate 5B). Coenenchymal sclerites are orange and they are mostly double discs reaching up to 0.07 mm in length and 0.05 mm in width (Plate 5C, Fig. 9 ). Spindles are less abundant, up to 0.10 mm in length, and 0.043 mm in width, with 4–5 whorls of warty tubercles (Plate 5C, Fig. 9 ). No anthocodial sclerites were obtained in the samples for study.

The illustrated colony (MCZ 36316) measures 45 cm in height, and 63 cm in width (Plate 5A).

Distribution. Baja California Sur, Acapulco, type localities; Mazatlán ( Table 4).

Remarks. This species was firstly described by Verrill (1868) as a variety of E. nobilis to separate the large flabelliform colonies of La Paz, Baja California, collected by Captain Pedersen from the short branched, more compact colonies of Panama and Nicaragua, E. nobilis . As a matter of fact the largest Eugorgia specimens examined in all collections belong to E. excelsa . In 1870 Verrill provided a fuller description of E. nobilis var excelsa , and included the locality of La Paz, collected by Major Rich, and Acapulco, collected by Professor Agassiz. Although it lacked of illustration and holotype designation, Verrill’s description (1870) of this species is complete and consistent with the syntype series. We consider that this variety is different enough from E. nobilis to be treated as another species.

Eugorgia excelsa and E. ampla are the species that reach the largest sizes found in the collection, they both are bushy and very similar in their morphology. However, E. ampla has thicker and flatter branches, but thinner stems, polyp mounds closer together, and colonies are stouter than in E. excelsa . Sclerites of E. ampla and E. excelsa are similar in colour and morphology, but they differ in size and composition. Spindles reach up to 0.15 mm in E. ampla , and 0.10 mm in E. excelsa . Spindles are more abundant in samples of E. ampla than in E. excelsa (Table 1).

Figures

FIGURE 9. Eugorgia excelsa (MCZ 36316), coenenchymal sclerites.