Fungiacyathus Sars 1872

Introduction

The fungiacyathids are known from the Late Cretaceous (Campanian of the Antarctic Peninsula, about 84 million years ago; see Filkorn, 1994) to the Recent. Species are found living in all ocean basins, including off continental Antarctica, and at depths of 70-6328 m, which is the greatest depth from which scleractinian corals have ever been recorded (Keler, 1976). The deepest record, from the Kuril-Kamchatcka Trench, equates to 20,762 feet, or 3.93 miles. The deeper-living species occur below the calcium carbonate compensation depth.

Fungiacyathids are exclusively azooxanthellate and exclusively solitary in growth form, always unattached, laying free on soft substrates. The largest known specimen is 62 mm in calicular diameter (Cairns and Zibrowius, 1997), but most are less than 25 mm in diameter. Their corallum is usually extremely fragile and therefore often damaged in collection. Twenty Recent species are known (Cairns et al., 1999): 6 in the nominate subgenus and 14 in Fungiacyathus (Bathyactis). Six to eight fossil species have also been described (see Filkorn, 1994). Three of the 20 species appear to reproduce primarily by fragmentation and subsequent regeneration. Several species are hosts for the galls of parasitic ascothoracidan Crustacea (Grygier and Zibrowius, 1985).

Characteristics

Solitary, free, discoidal coralla, usually with a flat or slightly concave base (septotheca) that bears ridged costae or granules. Septa highly dentate to laciniate, laterally ridged, and joined to adjacent septa by robust synapticulae. Columella spongy.

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Left: Fungiacyathus stephanus: Side view of a skeleton that was collected from Indonesia (depth 798 m). Diameter of corallum 37 mm (from Cairns, 1989). Right: F. marenzelleri: Side view of an isolated septum, showing trabecular ridges and synapticulae on the septal face. Specimen collected from off California (depth 4100 m). Length of septum 10 mm (from Cairns, 1994).

Discussion of Phylogenetic Relationships

No phylogenetic analysis has been made of the fungiacyathid species.

The subgenera are defined on the basis of septal number: the nominate subgenus has 5 cycles (96 septa) and Fungiacyathus (Bathyactis) has 4 cycles (48 septa); however, Zibrowius (in Cairns and Zibrowius, 1997) suggested that the subgenera be reconstituted based on the nature of the septal edges, i.e., straight or sinuous.

Other Names for Fungiacyathus Sars 1872

• Fungiacyathidae Chevalier 1987

References

Cairns, S. D. 1989. A revision of the ahermatypic Scleractinia of the Philippine Islands and adjacent waters, Part 1: Fungiacyathidae, Micrabaciidae, Turbinoliinae, Guyniidae, and Flabellidae. Smithsonian Contributions to Zoology, 486: 136 pp.

Cairns, S. D. 1994. Scleractinia of the temperate North Pacific. Smithsonian Contributions to Zoology, 557: 150 pp.

Cairns, S. D. 1995. The marine fauna of New Zealand: Scleractinia (Cnidaria: Anthozoa). New Zealand Oceanographic Institute Memoirs, 103: 210 pp.

Cairns, S. D. and H. Zibrowius. 1997. Cnidaria, Anthozoa: Azooxanthellate Scleractinia from the Philippine and Indonesian regions. Mémoires du Muséum National d'Histoire Naturelle, 172: 27-243.

Cairns, S. D., B. W. Hoeksema, and J. van der Land. 1999. Appendix: List of Extant Stony Corals. Attol Research Bulletin, 459:13-46.

Chevalier, J.-P. 1987. Ordre des Scléractiniares: Systematique. Pp. 679-753 In: Grassé (editor) Traité de Zoologie, 3(3) Masson, Paris.

Filkorn, H. F. 1994. Fossil scleractinian corals from James Ross Basin, Antarctica. Antarctic Research Series, 65: 96 pp.

Grygier, M. J. and H. Zibrowius. 1985. Diversity and range of scleractinian coral hosts of Ascothoracida (Crustacea: Maxillopoda). Annals de l'Institut Océanographique, Paris, 61(2): 115-138.

Keller, N. B. 1976. The deep-sea madreporarian corals of the genus Fungiacyathus from the Kuril-Kamchatka, Aleutian trenches and other regions of world ocean. Trudy Instituta Okeanologii, 99: 31-44 (in Russian).

Wells, J. W. 1956. Scleractinia. Pp. F328-F444 In: Moore, R. C. (editor) Treatise on Invertebrate Paleontology, Part F: Coelenterata. University of Kansas Press, Lawrence.