Acanthoaxis wirtzi, van Ofwegen & McFadden, 2010

van Ofwegen, Leen P. & McFadden, Catherine S., 2010, A new family of octocorals (Anthozoa: Octocorallia) from Cameroon waters, Journal of Natural History 44 (1 - 2), pp. 23-29 : 24-28

publication ID	https://doi.org/ 10.1080/00222930903359669
persistent identifier	https://treatment.plazi.org/id/067C8785-3243-9A58-929E-B2CCFE6247D0
treatment provided by	Felipe
scientific name	Acanthoaxis wirtzi
status	sp. nov.

Treatment

Acanthoaxis wirtzi View in CoL sp. nov.

( Figures 1–3 View Figure 1 View Figure 2 View Figure 3 )

Type material

Holotype: RMNH Coel. 39501, Cameroon, Botha Island , about 1 km off the mainland coast, and about 5 km north of Limbe city, snorkelling in murky water, 1–2 m

depth, 9–10 February 2007, coll. P. Wirtz. Paratypes: RMNH Coel. 39502, three specimens, same data as holotype .

Description

The holotype is 9 cm high and 7.5 cm wide ( Figure 2A View Figure 2 ). Three short stems arise from a common holdfast; one of these stems is only 1 cm long with apparently all the branches broken off. The two other stems branch laterally, forming two separate fans arranged parallel to each other. A few anastomoses are present in the lower part of the fans. The polyps are arranged spirally around the branches and are mostly retracted in dome-shaped coenenchymal mounds ( Figure 3C View Figure 3 ). The polyps have eight tentacles; because of the many retracted polyps we could not determine the number of pinnules on the tentacles with certainty.

Nowhere in the colony was any trace of sclerites found.

The axis is made of scleroproteinous gorgonin with a narrow, hollow, soft, crosschambered central core ( Figure 3A, G–I View Figure 3 ). Spines are present, arranged irregularly around the axis surface with the largest situated under the polyps. The larger spines branch at the tips ( Figure 3B, D, F View Figure 3 ). The surface of the axis is covered with round to oval depressions which mark the locations of desmocytes ( Figure 3E View Figure 3 ).

Variability

The paratypes ( Figure 1B–D View Figure 1 ) differ from the holotype in colony size and branch thickness.

Colour

Alive, the holotype was orange with somewhat darker polyps ( Figure 1A–C View Figure 1 ). Preserved it is white; the axis is brown.

Etymology

Named after the collector, Peter Wirtz, Department of Biology, University of Madeira.

Remarks

The round to oval depressions on the axis of octocorals was first noticed by Bourne (1899), who used the term desmocyte to describe cells in the epithelium of the blue coral Heliopora sp. that anchor the epithelium to the axis, and leave these depressions on the axis surface. Later, Bayer and Stefani (1987: 950, fig. 6e,f) and Alderslade (1998, several figures) depicted them for isidid species, and Muscatine et al. (1997) for stony corals.

Because of the spiral arrangement of polyps and the presence of an axis made of gorgonin with a narrow, hollow, soft, cross-chambered central core we exclude the possibility that what we have here is some clavulariid species overgrowing the skeleton of a hydroid or black coral.