Trichogorgia Hickson, 1904

Cordeiro, Ralf T. S., 2019, A review of the genus Trichogorgia (Cnidaria, Octocorallia), including descriptions of new species, Zootaxa 4706 (4), pp. 517-530 : 518

Genus Trichogorgia Hickson, 1904

Trichogorgia Hickson 1904: 222 .— Kükenthal 1919: 497; 1924: 383.— Deichmann 1936: 223.— Bayer 1956: F216.— Bayer & Muzik 1976: 78-79.— Williams 1992: 268.— Castro et al. 2010: 821 .— Weinberg 2013: 406.

Malacogorgia Hickson, 1904: 226 .

Type species. Trichogorgia flexilis Hickson, 1904 , by original designation.

Diagnosis. Chrysogorgiids with uniplanar flabellate or lyrate colonies, with long terminal branches. Axis with or without calcareous deposits, becoming very thin and flexible at terminal branches. Polyps biserial on all sides of terminal and subterminal branches, widely spaced or more crowded terminally. Sclerites present or absent; if present, in the form of very thin scales (double disks or double pads), with finely serrated edges ( Bayer & Muzik 1976: 79)

Remarks. Six species currently belong to this genus ( Table 1 ), which fit into at least four general colony forms: lyrate, flabellate, slender planar and bushy ( Fig. 1A ). A seventh dubious species was described by Hiles (1899) as Chrysogorgia constricta from New Britain, which was later transferred to Trichogorgia by Kükenthal (1919). Soon after its description, authors started to question its identity ( Versluys 1902; Kükenthal 1919). The uncertainty emerged mostly because its body wall sclerites are spindles arranged in eight-line chevrons ( Hiles 1899, p. 195–196, pl. XXII. figs. 8, 9, 10), whereas in Trichogorgia , sclerites are only scales, when present ( Williams 1992), never in chevron. It is also uncertain if specimens from Amboina Island ( Hentschel 1903) correspond to the same species. Herein, I suggest to keep that species in its original genus ( Chrysogorgia ), until the types are re-examined. With the two new names given in this manuscript, the genus expands its diversity to eight species.

Distribution. Probably cosmopolitan, mostly found at mesophotic depths, 12 to 662 m ( Fig. 1B, C ).

Figures

FIGURE 1. Forms and distribution of the genus Trichogorgia. A: four common colony shapes in the genus (left to right): lyrate, flabellate, slender planar and bushy, respectively; B: comparison between bathymetric ranges of Trichogorgia species; C: distribution map for the genus. Depth given in meters (m).