Circularius wilsoni Mcfadden & Van Ofwegen 2017, n. comb.
Creators: name: Mcfadden, Catherine S.
name: Van Ofwegen, Leen P.
Publisher: name: Zenodo
Year: 2017
Subjects: Biodiversity
Taxonomy
Animalia
Cnidaria
Anthozoa
Alcyonacea
Parasphaerascleridae
Circularius
Circularius wilsoni

description: Circularius wilsoni (Thomson, 1921), n. comb.
Fig. 5e, 10–11
Alcyonium (Erythropodium) Wilsoni Thomson, 1921: 160 –162; Thomson, 1923: 50.
Parerythropodium Wilsoni Tixier-Durivault, 1954a: 265.
Alcyonium wilsoni Williams, 1992a: 298 –300; 1992b: 381, 396, fig. 21E.
Material examined. CASIZ 222396 (SAF446), RMNH Coel. 40208 (SAF447), RMNH Coel. 40207 (SAF448), SAM (SAF449), SAF456, South Africa, Western Cape, Cape Peninsula, Star Walls, 34º02.472'S, 18º18.083'E, depth 20–29 m, coll. C.S. McFadden, 24 March 2008. UF3876, South Africa, Western Cape, Capetown, Hout Bay / Vulcan Rock, depth 24 m, coll. J. Starmer, 0 1 April 2000.
Remarks. Williams (1992a) provides a good description of this species. Similar to the material he examined, the colonies we collected were growing on the surfaces of other organisms, specifically mussels and polychaete tubes (Fig. 5e). Small colonies, most <5 mm in diameter, occur in aggregations of 20 or more, typically separated from one another by a few mm to 1 cm. These aggregations appear to arise as the result of colony fission and the subsequent movement of clonemates away from each other, as has been documented in Discophyton rudyi (Verseveldt & Ofwegen) (McFadden 1991). In a few cases adjacent colonies are still connected by a thin membrane, but in most this connection has been lost and the intervening substrate has been overgrown by sponges or other encrusting organisms. Williams (1992a) included few SEM images of the sclerites of this species, so we include additional images here to facilitate comparisons with similar species (Figs. 10–11). We also note that in life colonies are pink, but they fade to cream, white or beige in ethanol; the sclerites are colorless.
Superficially, C. wilsoni n. comb. resembles the pink color morph of Tenerodus fallax n. comb., but it can be distinguished from that species in the field by its habit of forming aggregations of very small colonies (Fig. 5e). C. wilsoni can be further distinguished from T. fallax by the sclerites, which are predominantly spindles and clubs (Figs. 10–11) rather than tuberculate spheroids (Figs. 15–16). Although Williams (1992a) speculated that Alcyonium wilsoni might represent a variant of Alcyonium fauri (= T. fallax n. comb.), the marked difference in sclerite form between the species and molecular phylogenetic analyses (Fig. 1) both confirm that they are clearly different species. Phylogenetic analyses suggest that C. wilsoni n. comb. is closely related to Leptophyton. That genus does not have sclerites arranged as a collaret and points in the polyps, however, and the colonies are typically much larger and have branched lobes.
description: Published as part of Mcfadden, Catherine S. & Van Ofwegen, Leen P., 2017, Revisionary systematics of the endemic soft coral fauna (Octocorallia: Alcyonacea: Alcyoniina) of the Agulhas Bioregion, South Africa, pp. 451-488 in Zootaxa 4363 (4) on pages 470-471, DOI: 10.11646/zootaxa.4363.4.1, http://zenodo.org/record/1114473