Circularius, Mcfadden & Van Ofwegen, 2017

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, Zootaxa 4363 (4), pp. 451-488 : 469-470

Circularius , n. gen.

Type species. Alcyonium wilsoni Thomson, 1921 by original designation

Diagnosis. Colonies lobate, lobes often arising from encrusting, membranous base. Polyps retractile. Sclerites predominantly spindles and clubs. Some radiates may be present in base of colony. Polyps with spindles arranged to form collaret and points. Small rods in tentacles. Interior of colony with same sclerite types as surface. Sclerites colorless.

Etymology. From the Latin circulor meaning to gather a group around oneself, in reference to the species’ tendency to occur as aggregations of small colonies. Gender: masc.

Remarks. Circularius n. gen. is distinguished from other genera in family Leptophytidae by the arrangement of sclerites in the polyps, which form a collaret and points. Species in the genera Alcyonium (Alcyoniidae) and Gersemia (Nephtheidae) also have a collaret and points. Gersemia , however, lacks clubs, and has predominantly radiates in the colony surface and few or no sclerites in the colony interior. Alcyonium has the coenenchymal sclerites arranged in two distinct layers. In contrast, in Circularius n. gen. the same sclerite types occur throughout the polyps, surface and interior of the colony. The growth form of Circularius n. gen. superficially resembles that of the northern hemisphere genus Discophyton McFadden & Hochberg , but in that genus the polyps lack sclerites and the coenenchymal sclerites are large, irregular forms. Molecular analyses place Circularius n. gen. in a clade with other genera endemic to South Africa, and sister to Leptophyton ( Fig. 1 ).

Figures

FIGURE 1. Maximum likelihood phylogeny of Octocorallia based on combined, partitioned analysis of 28S rDNA, COI and 16S mtDNA.South African species and clades are identified in blue. Filled circles indicate nodes with>70% bootstrap support and Bayesian posterior probabilities>0.95 (shown for South African clades only). Strongly supported clades (bootstrap 70%) with no South African members have been collapsed to facilitate readability. Phylogenetic position of Protodendron repens indicated with *.