Tobagogorgia hardyi, Sánchez, 2007

Sánchez, Juan A., 2007, A new genus of Atlantic octocorals (Octocorallia: Gorgoniidae): systematics of gorgoniids with asymmetric sclerites, Journal of Natural History 41 (9 - 12), pp. 493-509 : 501-504

Tobagogorgia hardyi gen. et sp. nov.

( Figures 9 , 10 )

Holotype: USNM 1093840 (ethanol preserved) . Paratypes: USNM 1093841 and 1093842 (dry preserved). All specimens from sand and rubble basin of Man-of-War Bay (off Booby Island coral reef), Charlotteville, Tobago ( Trinidad and Tobago), western Atlantic, at 27 m (collected using scuba diving), 16 August 2002 .

Diagnostic characters. The genus and species can be distinguished by the presence of both enlarged ornamentation with multiple spines on the convex side of the asymmetrical sclerites from the surface layer ( Figure 9B ), and irregularly bent spindles in the inner layer ( Figure 9D ). Cylindrical branches and polyps placed throughout the branch (no rows or grooves) can distinguish this genus from Leptogorgia , which have analogous sclerite forms. Type species: Tobagogorgia hardyi spec. nov.; by monotypy and original designation.

Description. Tobagogorgia hardyi has overall morphological features as other gorgoniid octocorals, which include spindles, 0.3 mm and complex (many internal geometrical/ fractal subwarts) warts (or tubercles) disposed in transverse girdles, usually, 0.02 mm wide ( Sánchez et al. 2003b). The holotype has slimy, whip-like, and sparsely branched colonies (one main branch and two to three daughter branches) up to 300 mm in length ( Figure 9A ). Its branches are thin and cylindrical (2–4 mm width). Living colonies are yellow ( Figure 10 ) with even brighter polyps (grey when dry, black in alcohol). The polyps are placed throughout the branches and have robustly ornamented rods 0.12–0.16 mm long ( Figure 9C ) but do not form any particular structure. No rows or series of polyps are observable. Sclerites are colourless. Surface layer sclerites are composed of bent (asymmetrical) and ornamented spindles 0.1–0.17 mm long ( Figures 2A–D , 9B ). The inner sclerite layer harbours two different forms: small radiate capstans (0.05–0.16 mm: Figure 9D ) and acute irregularly bent ornamented spindles (up to 0.2 mm long: Figure 9E ).

Etymology. The new genus is named for the island Tobago and the suffix gorgia commonly used for gorgoniid genera (feminine gender). The species is named in honour of Jerry D. ‘‘Dave’’ Hardy, Jr who has dedicated his career to the study of biodiversity in Tobago.

Species comparisons. The molecular results by Aguilar and Sánchez (2007a), which showed that Tobagogorgia did not group close to any gorgoniid genera or species, validated a separation of this species as a new genus in spite of its colonies and sclerites resembling those of a number of other valid genera. Tobagogorgia hardyi is a gorgoniid species that does not have symmetrically sculptured spindles (e.g. Figure 12 ). The combined set of sclerites of Tobagorgia (e.g. both asymmetrical and irregularly bent spindles) makes it different from the diagnostic characters of homologous genera such as Muriceopsis and Pinnigorgia ( Figures 5–9 ). The latter two genera are also profusely branched, including pinnate patterns, whereas T. hardyi has one or two branches only. Externally, T. hardyi looks similar to some Leptogorgia colonies that also barely branches but it is clear that the sclerites are very different and thus their phylogenetic divergence.

Clade 4. Gorgoniids with long and spiny spindles

Surface coenenchyme with long spindles with multiple (regular or irregular) rows of ornaments, occasionally spiny towards one side. This clade includes the Leptogorgia ridouri and L. sanguinolenta groups proposed by Grasshoff (1988).

Figures

Figure 2. Diverse species of gorgoniids. (A) Phyllogorgia dillatata (Brazil, USNM 5252); (B) Gorgonia mariae (Carrie Bow Cay, Belize); (C) G. ventalina (San Salvador, Bahamas); (D) Pacifigorgia elegans (Brazil, USNM 50953); (E) P. agassizi (Colombia, Invemar collection); (F) Pseudopterogorgia sp. (Carrie Bow Cay, Belize); (G) Pterogorgia anceps; (H) Leptogorgia stheno (Bocas del Toro, Panama´).

Figure 5. Photographs of gorgonian corals from gorgoniids with asymmetrical spiny sclerites (Clade 3) in their natural environment or dry preserved. (A) Muriceopsis flavida (Lamarck) (Caribbean Sea, Bocas del Toro, Panama´; 15 m); (B) M. bayeriana Sánchez (Caribbean Sea, Bocas del Toro, Panama´; 2 m); (C, D) Pinnigorgia platysoma (Nutting) (Northern Territory Museum, Darwin, Australia; C11674; C12123); (E) P. flava (Nutting) (C11661). (C–E) Courtesy: Phil Alderslade.

Figure 6. SEM stereopairs of Muriceopsis sulphurea Donovan (USNM 5298), Brazil. (A) Detail from (C) of the warts from sclerites of the surface coenenchyme; (B–H) different forms from the sclerites of the surface. Scale bars: 0.01 mm (A); 0.1 mm (B–D, F, H); 0.02 mm (E, G).

Figure 7. SEM stereopairs of Pinnigorgia flava (Nutting). (A–C) C11661, scales; (D–F) P. USNM 92320. Scale bars: 0.02 mm (A–C, E, F); 0.01 mm (D).

Figure 8. SEM stereopairs of Pinnigorgia platysoma (Nutting). (A–C) C12123; (D–F) C11674. Scale bars: 0.01 mm (A–C, E, F); 0.02 mm (D).

Figure 9. Holotype of Tobagogorgia hardyi, gen. et sp. nov. (A) Preserved alcohol colony, detail and a dry colony paratype; (B) spiny bent spindles from the surface layer; (C) polyp sclerites; (D) capstans from the inner layer; (E) spindles from the inner layer. Scale bars: 0.02 mm (B–E).

Figure 10. Colony of Tobagogorgia hardyi, gen. et sp. nov. off Bobby Island, 30 m, Tobago, Trinidad and Tobago, March 2006. Inset: complete colony.

Figure 12. Surface sclerites of several gorgonian corals. (A–D) Tobagorgia hardyi new species; (E, F) Filigorgia schoutedeni (Stiasny); (G) Leptogorgia virgulata Linnaeus. (A–F) SEM stereopairs. Scale bars: 0.02 mm.