Ofwegenum coronalucis sp. nov.

Figs 1, 2A, B, 3H, I, 7, 8, 9, 10A-D, 11

Material examined.

Holotype. Oman • Dhofar, Mirbat, Michel's Reef; 16.9433°N, 54.7300°E; 25-30 m depth; 20 January 2022; coll. C.S. McFadden and K. Samimi-Namin; UF 17263 (BOMAN-08362).

Paratype. Oman • same data as holotype; SMNHTAU_ Co _39048 (BOMAN-08351) .

Other material.

Oman • Dhofar, Mirbat, Frankincense; 16.9662°N, 54.6900°E; 24-30 m depth; 19 Jan 2022 ; coll. C.S. McFadden; UF 15819 (BOMAN-08345) • Dhofar, Mirbat, near Frankincense; 16.9688°N, 54.6877°E; 24-29 m depth; 21 Jan 2022 ; coll. C.S. McFadden and K. Samimi-Namin; UF15882 (BOMAN-09175) • same collection data as for preceding; UF 15877 (BOMAN-09166) • same collection data as for preceding; in situ photo, microscope slides and molecular data only; BOMAN-09174. Unknown • Aquarium trade, Chicago, IL, USA; July 2013; coll. A. Parrin; SMNHTAU_Co_38223.

Description.

The holotype consists of several fragments of a colony; the largest is 10 mm in diameter (Fig. 3H). The colony consists of multiple capitate polyparia on sterile stalks; side branches connect adjacent stalks to one other at the base to form an encrusting mat. Most polyps are contracted, with polyps widely set on the polyparium (Figs 3H, 9A, B).

Sclerites of the coenenchyme are spindles and rods up to 0.40 mm long with low, simple tubercles or areas of thickening forming concentric, raised rings (Fig. 7A). The polyp body contains similar but shorter rods that appear to be arranged 'en chevron’ when the polyp is extended (Fig. 2A). These sclerites are usually blunt and have a crystalline texture at both ends (Fig. 7A). The length of the sclerites decreases along the polyp body towards the base of the tentacles (Fig. 7A).

The tentacles and pinnules contain numerous platelets and flattened rods (i.e., finger-biscuits) up to 0.10 mm long (Fig. 7B), arranged on the aboral side of the tentacles (Fig. 2A, B). Some of these sclerites have median constrictions, side notches, or depressions at one or both ends resembling figure-eight shapes (Fig. 7B). There are also numerous irregularly shaped platelets with side notches or side branches, up to 0.05 mm in length (Fig. 7C), that are distributed around the mouth and base of the tentacles on the oral side. These sclerites are reflective in light (Fig. 2A, B).

Colour.

In life, colonies appear brown with blue-green tentacles. After preservation in ethanol, they are creamy white. Sclerites colourless.

Morphological variations.

UF 15882 and BOMAN-09174 have slightly thinner spindles and rods both in the coenenchyme and polyp body (Fig. 8A). In addition, the polyp sclerites have fewer side notches and depressions compared to the holotype (Fig. 8B). Photos of the live specimens suggest that some of the polyps do not have the reflective sclerites around the mouth (Figs 9E, F, 10C, D).

SMNHTAU_Co_38223 comes from the aquarium trade in the U.S. Its commercial source is assumed to be Jakarta, Indonesia (A. Parrin, pers. comm. 12 Aug 2013), but the original collection locality remains unknown. This colony is tentatively assigned as O. aff. coronalucis based on its sclerite features and genetic similarity to this species (Fig. 16). However, it differs from the other material in having a blue colour in the coenenchyme and shorter tentacle sclerites up to 0.07 mm long. Such differences might be due to a prolonged exposure to the artificial aquarium environment.

Remarks.

Ofwegenum coronalucis sp. nov. differs from its congeners in having irregularly shaped sclerites with side notches or side branches around the polyp mouth that reflect light (Figs 2A, B, 7C, 8C). Additionally, the tentacle platelets have narrow median constrictions compared to the other species (Figs 7B, 8B).

Distribution.

Oman.

Etymology.

The species name is from the Latin corona (crown) and lucis (of light), referring to the reflective ring of sclerites around the polyp mouth in the live specimens.