Stragulum, Ofwegen, Van, 2011

Ofwegen, Van, 2011, A probably invasive new genus and new species of soft coral (Octocorallia: Alcyonacea: Clavulariidae) from Brazil, Zootaxa 3107, pp. 38-46 : 39

Stragulum , new genus

Diagnosis. Colonies form encrusting sheets. Sclerites are spindles, crosses, and radiates in the upper layer of the coenenchyme, which become smaller on the polyp mounds. The basal layer of the coenenchyme has fused sclerites. Polyps are retractile and unarmed. When preserved, colonies are red with reddish sclerites or white with colourless sclerites. Live colonies are white or red with brownish or white polyps.

Type species: Stragulum bicolor n. sp., by original designation and monotypy.

Etymology. The generic name is the Latin stragulum, a covering, carpet, mattress, referring to the sheets the colonies form. The gender is neuter.

Remarks. One of the specimens collected in 2009 at Paranaguá was sent to C.S. McFadden for molecular study. She confirmed we were dealing with a new genus that falls into a clade with Paratelesto Utinomi, 1958 , Rhodelinda Bayer, 1981 (both Clavulariidae ), and Tubipora Linnaeus, 1758 (Tubiporidae) . Quite high bootstrap support was found grouping it with two specimens of Paratelesto from Rajah Ampat ( Indonesia), and equidistant from Tubipora . All of these three genera have in common that they possess fused sclerites. Tubipora differs from Stragulum n.gen., n. sp. in having a massive structure constructed completely of fused sclerites except within the polyps. Paratelesto has fused sclerites in the interior and forms bushes instead of encrusting sheets, and Rhodelinda differs in having relatively tall, narrow conical calyces of inseparably fused sclerites, which arise from colonial stolons instead of encrusting sheets.

Besides Rhodelinda, Bayer (1981) mentioned one more clavulariid genus with fused sclerites, Cyathopodium Verrill, 1868 , and described three more, Bathytelesto , Scyphopodium and Stereotelesto . Like Rhodelinda these four genera also differ from Stragulum n.gen., n. sp. in having inseparably fused sclerites in calyces. Moreover, none of these genera form encrusting sheets. Noteworthy, Williams (1989) discussed the genera Bathytelesto , Rhodelinda , Scyphopodium and Stereotelesto and concluded that of these four genera only Scyphopodium could be easily differentiated from the others.