INTRODUCTION
Prior to this publication, only two species of antipatharian corals, Taxipathes recta Brook (Reference Brook1889) and Cladopathes plumosa Brook (Reference Brook1889) were recorded from Ascension Island. A third species from Ascension, Dendrobrachia fallax, originally thought to be an antipatharian, was later shown to be a gorgonian coral (Opresko & Bayer, Reference Opresko and Bayer1991). Both T. recta and C. plumosa are deep-water species that were collected during the voyage of HMS ‘Challenger’. In this paper a third deep-water species, as well as four shallow-water antipatharian species are described from Ascension for the first time, and the relationship of the shallow-water fauna to the eastern Atlantic fauna is discussed.
MATERIALS AND METHODS
In addition to a review of the pertinent literature, the collections of the U.S. National Museum of Natural History (USNMNH) of the Smithsonian Institution, Washington, DC, were surveyed for records of antipatharian corals collected at Ascension Island. Eleven specimens were found in the USNMNH collections, nine from shallow-water at depths of 32 m or less (Note: USNMNH catalogue numbers are prefixed with USNM). The survey of the open literature revealed records of two, primarily deep-water species that were reported as being collected near Ascension Island, one from within 10 km of the island (a subsample of one of these is also in the USNM collection). In total, there are twelve records of specimens from the area, representing seven species in six genera and four families.
RESULTS
SYSTEMATICS
ANTIPATHIDAE
Stichopathes occidentalis (Gray, Reference Gray1860) (Figure 1A)
Three Ascension Island specimens of this species are in the USNMNH collections; two were collected off Boatswain Bird Rock, one from the vertical face of a drop-off at 28 m depth (USNM 99872), the second growing from the side of a large boulder at 30 m (USNM 99546). The third specimen was found south of Southwest Bay at a depth of 32 m (USNM 1229810).
The species S. occidentalis was originally described from Turk's Island in the West Indies (Gray, Reference Gray1860). It was later reported from the west coast of Africa (Islas das Rolas) by Broch (Reference Broch1920). The Ascension Island specimens differ from the type of S. occidentalis in having spines that are slightly more acute, although in respect to size (about 0.2 mm) and surface ornamentation, they are quite similar. A similar morphotype occurs in Bermuda at depths of 73–110 m (unpublished observations).
MYRIOPATHIDAE
Antipathella wollastoni (Gray, Reference Gray1857) (Figure 1B)
Two Ascension Island specimens of this species are in the USNMNH collection, one collected off the east end of the island at a depth of 6 m (USNM 78686) and the other south of Southwest Point at 32 m (USNM 79389). The species is only known from the eastern Atlantic; it has been recorded from Madeira, Cape Verde, the Azores and the Canary Islands (see Brito & Ocaña, Reference Brito, Ocaña and Lemus2004), as well as from the western Mediterranean (Ocaña et al., Reference Ocaña, Opresko and Brito2006). It forms rather large bushy colonies with elongate branchlets. It is similar in general morphology to Antipathella subpinnata which is known primarily from the Mediterranean.
Tanacetipathes spinescens (Gray, Reference Gray1857) (Figure 2)
Three Ascension Island specimens of this species are in the USNMNH collections; one collected off the south-west end of the island in 20 m (USNM 78687); the second from south of Southwest Bay in 32 m (USNM 79390); and the third from off Portland Point in 24 m (USNM 99680). This species forms bushy, densely pinnulated colonies. Branches arise from all parts of the colony. The species was originally described from Cape Palmas (Gray, Reference Gray1857). A very similar if not identical species is Tanacetipathes squamosa (Koch, Reference Koch1886) described from Islas das Rolas in the Gulf of Guinea. The two species were synonymized by Broch (Reference Broch1920).
Tanacetipathes cf. cavernicola Opresko, Reference Opresko2001 (Figure 3A)
Tanacetipathes cavernicola was originally described from Madeira where it was found growing in an underwater cave at a depth of 9–10 m (Opresko, Reference Opresko2001). It has also been reported from the Canary Islands (Brito & Ocaña, Reference Brito, Ocaña and Lemus2004). The specimen from Ascension Island was collected off the east end of the island (USNM 78688; depth not recorded). It differs from the type in having more secondary pinnules on the posterior primary pinnules.
Fig. 1. (A) Stichopathes occidentalis (USNM 99872); (B) Antipathella wollastoni (USNM 78686).
Fig. 2. Tanacetipathes spinescens. (A) In situ (photograph: Shallow Marine Surveys Group); (B) USNM 99680.
Fig. 3. (A) Tanacetipathes cf. cavernicola (USNM 78688); (B) Lillipathes sp. (USNM 91419).
SCHIZOPATHIDAE
Lillipathes sp. (Figure 3B)
The genus Lillipathes Opresko (Reference Opresko2002) is known primarily from the Pacific. This is the first published record from the Atlantic. The specimen from Ascension Island (USNM 91419) was collected in 586 m by the RV ‘Oman Sea I’ (6 August 1991); however, the exact location was not recorded. Species of Lillipathes are characterized by having simple pinnules arranged in four longitudinal rows along the stem and branches, and also with the pinnules grouped together in alternating pairs. Species are differentiated by the length and density of the pinnules, and size of the polyps and spines. The specimen from Ascension Island resembles L. wingi Opresko, Reference Opresko2005, in terms of the length and density of the pinnules; however, it differs from that species in having slightly smaller spines (0.06 vs 0.1 mm).
Taxipathes recta Brook, Reference Brook1889 (Figure 4A)
This species was originally described in the ‘Challenger’ Report (Brook, Reference Brook1889). The type was collected approximately 6.5 km west of Ascension Island (7°54′20″S 14°28′20″W) at a depth of 420 fathoms (768 m). It has not been reported from any other locality. The species forms branched, pinnulated colonies with simple pinnules arranged bilaterally and in alternating semispiral groups of three. The arrangement of the pinnules is very similar to that which occurs in colonies of Parantipathes.
Fig. 4. (A) Taxipathes recta Brook, Reference Brook1889, digital scan of original illustration (Brook, Reference Brook1889, pl. 7, fig. 1); (B) Cladopathes plumosa Brook, Reference Brook1889, digital scan of original illustration (Brook, Reference Brook1889, pl. 2, fig. 3).
CLADOPATHIDAE
Cladopathes plumosa Brook, Reference Brook1889 (Figure 4B)
According to the records of the Natural History Museum, London, a specimen identified as this species (Reg. No. 1889.7.9.9a) was collected off Ascension Island during the ‘Challenger’ Expedition (see Opresko, Reference Opresko2003). The depth and exact locality were not recorded. The species was first described by Brook (Reference Brook1889) from the Prince Edward Islands in the Indian Ocean. It was collected at a depth of 310 fathoms (558 m). The species forms large, branched, pinnulated colonies (see Opresko, Reference Opresko2003, for detailed description). The pinnulation pattern varies in regularity. The primary pinnules are arranged mostly in clusters of three (rarely two or four). The anterior-most primary pinnules usually have one or two secondary pinnules (range 0–4), and the posterior primary pinnules are usually simple (rarely subpinnulate). Tertiary pinnules are sometimes present on secondary pinnules. Subpinnules may occur in subopposite pairs. In the specimen from Ascension Island the pinnules are more evenly spaced than in the type, the secondary pinnules sometimes occurring in groups of three as well as in subopposite pairs, and some of the secondary pinnules have subopposite pairs of tertiary pinnules.
DISCUSSION
The shallow-water antipatharian fauna of Ascension Island shows its closest affiliation to the fauna of the eastern Atlantic. Of the four shallow-water species, three are only known from the eastern Atlantic and one is amphi-Atlantic. Tanacetipathes spinescens and Stichopathes occidentalis were the two most commonly collected shallow-water species.
ACKNOWLEDGEMENTS
The author wishes to thank the individuals who collected the Ascension Island antipatharians and donated them to the Smithsonian Institution, including R. Irving, J. Taylor, M. Mcdowell and the staff of the Grice Marine Biological Laboratory. Many thanks also to T. Molodtsova, M. Bo and a third anonymous referee for their comments and suggestions. We are grateful to the Shallow Marine Surveys Group and the South Atlantic Environmental Research Institute for organizing the expedition. We are also very grateful to the Ascension Island Government, the members of staff at the Conservation Centre and Ascension Island Dive Club for their cooperation, accommodation and hospitality. Finally we are grateful to British Forces South Atlantic Islands for their logistic support.
FINANCIAL SUPPORT
The funding for this work came from a grant to the Shallow Marine Surveys Group from the Darwin Initiative (EIDCF012). Funding for the author's research was provided, in part, by a grant from the US Department of Justice to the Smithsonian Institution.
