All three species of Ptychodactiaria belong to order Actiniaria (Cnidaria: Anthozoa)

Abstract

Ptychodactiaria, currently recognized as an order equivalent to Actiniaria (sea anemones sensu stricto) and Scleractinia (`true' or hard corals) of cnidarian class Anthozoa, contains three monotypic genera, Dactylanthus, Ptychodactis, and Preactis, in two families, Ptychodactiidae and Preactiidae. Features that had been considered distinctive to the order among hexacorallian anthozoans were that gametes mature in protrusions from the mesenteries, as in octocorallian anthozoans, and that gametes do not mature embedded in mesogloea. However, we found that ptychodactiarian gametes develop in the mesenteries, surrounded by mesogloea, as in other sea anemones. We conclude that the three species constitute a clade, the most distinctive feature of which is medially fused mesenteries at the proximal end of the body. This clade merits subordinal status within order Actiniaria. We rede¢ne Ptychodactiaria and its component taxa, moving Dactylanthus from family Ptychodactiidae to family Preactiidae.

Ptychodactis aleutiensis, a new species of ptychodactiarian sea anemone (Cnidaria: Anthozoa: Actiniaria) from the Aleutian Islands, Alaska

“…Cappola & Fautin (2000) adapted the definition of family Ptychodactiidae and genus Ptychodactis from the original description by Appellö f (1893). We have further adapted the definition to accommodate P. aleutiensis sp.…”

“…There have been inconsistencies in characterizing suborder Ptychodacteae (Cappola & Fautin 2000). One concerns siphonoglyphs, which Carlgren (1949), Cappola & Fautin (2000), and Grebel'nyi (2007) stated are absent, but which are present in both P. patula and P. aleutiensis sp.…”

“…Suborder Ptychodacteae was established as a taxon of order Actiniaria (true sea anemones) by Stephenson (1921); Carlgren (1949) raised it to ordinal rank, but Cappola & Fautin (2000) determined that much of the anatomy used by Carlgren (1949) to justify order Ptychodactiaria had been misinterpreted or was insignificant, and returned the ptychodactiarians to subordinal status. Phylogenetic analyses by Berntson et al (1999) and Daly et al (2002) that included the ptychodactiarian Dactylanthus antarcticus (Clubb, 1908) showed ptychodactiarians nested among members of order Actiniaria.…”

“…The column of members of the family Preactiidae has tentaculate vesicles (Clubb 1908;England & Robson 1984), and the animals are highly mobile predators of soft corals (members of anthozoan subclass Octocorallia) (England & Robson 1984;Dayton et al 1997). The only genus of family Ptychodactiidae, Ptychodactis, is confined to northern latitudes and lacks tentaculate vesicles (Appellö f 1893 ;Carlgren 1921;Cappola & Fautin 2000).…”

Catalog to families, genera, and species of orders Actiniaria and Corallimorpharia (Cnidaria: Anthozoa)

“…Following the description of a third genus and species in England & Robson (1984) [Ref. 61], Cappola & Fautin (2000) [Ref. 1594] returned Ptychodactiaria to Actiniaria, a placement supported by molecular sequence data [Ref.…”