Parasphaerasclera grayi Thomson & Dean 1931

Parasphaerasclera grayi (Thomson & Dean, 1931) new record

(Figs. 2A,B, 3, 4; Tabs. 1, 2)

Nidalia grayi Thomson & Dean, 1931: 37, Pl. 2, Fig. 2.

Eleutherobia grayi Verseveldt & Bayer 1988: 33 –34, Figs. 24, 25; Williams 2001: 210–216, Figs. 1–10. Benayahu et al. 2004: 550 (recorded only); Dautova & Savinkin 2009: 4 –10, Figs. 3–7.

Parasphaerasclera grayi McFadden & Ofwegen 2013: 70, 71, 78.

Material examined. WAM Z54774, six whole specimens, Station 69/K11, unnamed outcrop NW Black Rocks, close to White Island, NW Australia, 14.9741° S, 124.3974° E, SCUBA, depth 12 m, coll. M. Bryce, 17 October 2011.

Description. In total six upright, unbranched colonies were collected. They are digitiform, symmetrical with a wide base tapering distally towards the rounded apex of the polyparium (Fig. 2A,B) and were always growing in pairs, arising from a common, polyp-free, one mm thick, encrusting holdfast. The colonies vary in size, but are in general very similar in shape, colour, arrangement of polyps and sclerite composition. The polyp-free basal portion of each colony is very short and occupies only 10 % of the total colony length. Polyps are monomorphic, large, retractile, quite numerous, evenly distributed over the colony and are translucent when fully extended and the coenenchymal mounds associated with the polyps are narrow. Pair one consists of one colony that is 31 mm in total length, with an apex 4 mm in diameter and a base 10 mm in diameter, together with a smaller colony that is 5 mm in total length with an apex 4 mm in diameter and a base 9 mm in diameter. Pair two consists of one colony that is 25 mm in total length, with an apex 5 mm in diameter and a base 10 mm in diameter, together with a smaller colony that is 13 mm in total length with an apex 3 mm in diameter and a base 6 mm in diameter. Pair three consists of one colony that is 19 mm in total length, with an apex 5 mm in diameter and a base 8 mm in diameter, together with a smaller colony that is 9 mm in total length with an apex 5 mm in diameter and a base 7 mm in diameter.

In the surface of the polyparium, including the coenenchymal mounds, the majority of sclerites are 6, 7- and 8- radiates and rodlets 0.04–0.08 mm long and crosses 0.03–0.07 mm in diameter (Fig. 3). The smaller radiates are tuberculate capstan-like forms and the longer rodlets are essentially 8-radiates with more distant prominences and a smooth, often long, shaft.

The stalk surface is densely spiculated with irregular radiates 0.05–0.08 mm long, crosses 0.05–0.08 mm long and rodlets (Fig. 4 A).

The interior sclerites of the polypary are 6- and 7-radiate capstans 0.04–0.09 mm long, crosses 0.06–0.09 mm in diameter, and elongated rod-like sclerites 0.10–0.11 mm long (Fig. 4 B). The interior of the stalk coenenchyme is populated with sclerites consisting of rod-like forms 0.10–0.11 mm long with a smooth shaft and large warty prominences, and robust crosses around 0.09 mm in diameter are also occasionally present (Fig. 4 C).

Polyp sclerites are absent.

Colour. In situ the colonies were uniformly bright rusty orange with small, bright, light orange, rounded coenenchymal mounds. The polyp-free encrusting holdfast was uniformly rusty red. The polyps were transparent with bright white tentacles. The colour did not change on deck or in alcohol. In preserved specimens the surface and internal coenenchymal sclerites are brownish dark red to pale-ochre, the sclerites of the polyp mounds are paleochre, and the interior coenenchyme is pink.

Habitat. Steep, forward reef slope extending up to the reef crest at 14 metres. On the crest of the slope were small coral outcrops and the underlying base rock was covered with encrusting corals and soft coral communities, dominated by Sinularia and Sarcophyton as well as several species of gorgonian. The slope was dissected by narrow surge grooves with vertical sides marked by caves and ledges extending to 20 metres. A small group of Parasphaerasclera grayi colonies was found attached to the wall in an overhang at 12 metres depth amongst other scattered soft corals.

Remarks. This species has a wide distribution in the Indo-Pacific region, but it is a new record in Australia (Table 1). More recently Benayahu et al. (2004) reported P. grayi as a new record from Taiwan, and in 2013 it was collected by WAM from Christmas Island (Richards, unpublished). McFadden & Ofwegen (2013) described material from Palau as P. aff. grayi and also discussed in detail the high variability of shape and size of the sclerites of specimens of P. grayi that have been described in the literature, stating the possibility that multiple species might be involved. They also pointed out the similarities between their P. aff. grayi and the P. grayi of Williams (2001) from the Solomon Islands, as well as the differences between their material and the P. grayi from Vietnam described by Dautova & Savinkin (2009) and the lectotype of P. grayi described by Verseveldt & Bayer’s (1988). Specimens from Palau and the Solomon Islands have tuberculated rods that lack a smooth waist. Our material agrees best with the well-illustrated and detailed re-description of the Vietnamese material and with the description of the lectotype based on the presence of distinctive smooth rod-like forms.