HOLAXONIA Studer, 1887

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 : 495-499

Suborder HOLAXONIA Studer, 1887

Family GORGONIIDAE Lamouroux, 1812

Gorgonian octocorals ( Holaxonia , see Bayer 1961; Sánchez et al. 2003a) with spindlederived sclerites in the colony surface,, 0.5 mm length, ornamented with complex (many internal geometrical/fractal subwarts) warts (or tubercles) disposed in transverse girdles, usually, 20 mm wide ( Sánchez et al. 2003b). Bayer and McIntyre (2001) proposed that calcite hydroxyapatite (CHAp) is only present in this family although it has not been found in all subfamilies and genera. Circumtropically distributed in shallow water (some symbiotic with zooxanthellae) with a few deep-water and sub-tropical species (e.g. Figure 2 ).

Clade 1. Gorgoniids with scaphoid sclerites

Gorgoniidae with scaphoid sclerites in the colony surface ( Figure 3 ), 4–10 rows of warts, presence of CHAp in their axes and/or bases, and flattened branches with polyps in series at the edges. Five genera: Gorgonia, Caribbean Pseudopterogorgia spp. (5 Antillogorgia ) (probably some Indopacific Pseudopterogorgia: Williams and Vennam 2001 ), Pterogorgia , Phyllogorgia , and Olindogorgia macgravi (see Bayer 1961, 1981; and phylogenetic relationships in Sánchez et al. 2003b). Distributed only in the western Atlantic from Bermuda to Brazil, mostly symbiotic (zooxanthellate).

Clade 2. Gorgoniids with capstan sclerites

Gorgoniidae with capstan-derived (short stout spindles: Figure 4 ) sclerites with symmetrical whorls or girdles (, six rows) of warts and derived forms (e.g. Leptogorgia spp. disk spindles: Figure 4D–F ) in the colony surface ( Figure 3 ); polyps placed in series along the branches. Presence of CHAp in their axes and/or bases. Leptogorgia (5 Lophogorgia , see Bayer 1961; and in part Grasshoff 1988; Williams and Lindo 1997), Eugorgia ( Verrill 1868) , Pacifigorgia (e.g. Breedy and Guzman 2003), Phycogorgia ( Bayer 1956) , and Guaiagorgia ( Grasshoff and Alderslade 1997) . Circumtropically distributed with a few deep-water and subtropical species ( Williams and Vennam 2001), mostly not symbiotic with zooxanthellae.

Clade 3. Gorgoniids with asymmetrical spiny sclerites

Gorgoniidae with long asymmetrical spiny sclerites in the colony surface. Sclerite spines long and robust.

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 3. SEM stereopairs and/or images of sclerites from the surface coenenchyme layer of species of gorgoniids with scaphoids sclerites (Clade 1). (A) Pseudopterogorgia acerosa (Tobago), stereopair; (B) Gorgonia mariae Bayer, stereopair (USNM 1007505); (C) Olindogorgia macgravi (Bayer); (D) Pterogorgia anceps (personal collection); (E, F) Pterogorgia citrina (USNM 1007406). Scale bars: 0.01 mm (A, C, E, F); 0.003 mm (B); 0.04 mm (D).

Figure 4. SEM stereopairs and/or images of sclerites from the surface coenenchyme layer of species of gorgoniids with capstan-derived sclerites (Clade 2). (A) Lophogorgia hebes Verrill, stereopair (USNM); (B) Lophogorgia alba Duchassaing and Michelotti (USNM 57091); (C) Phycogorgia fucata (Valenciennes) (USNM 56885); (D) Eugorgia rubens Verrill (USNM 50180); (E) Pseudopterogorgia australiensis (Ridley) (USNM 80952); (F) Leptogorgia virgulata (Lamarck) (USNM 1007414); (G) Pacifigorgia stenobrochis (Horn) (Eastern Pacific, personal collection). Scale bars: 0.01 mm (A, C, F, G); 0.02 mm (B, D, E).