Paraminabea hongkongensis, Lam & Morton, 2008

Lam, Katherine & Morton, Brian, 2008, Soft corals, sea fans, gorgonians (Octocorallia: Alcyonacea) and black and wire corals (Ceriantipatharia: Antipatharia) from submarine caves in Hong Kong with a checklist of local species and a description of a new species of Paraminabea, Journal of Natural History 42 (9 - 12), pp. 749-780 : 755-758

Paraminabea hongkongensis sp. nov.

( Figures 1G , 2 A–O)

Type material

Holotype: represented as fragments and sclerites, deposited in the Hong Kong Marine Caves Expedition Collection in the Natural History Museum, London. The single specimen was collected from Conic Island Cave, Hong Kong, on 22 October 2002 by P.A. Hodgson. No paratypes.

Diagnosis

Small, dome-shaped, orange colonies, 18 to 22 mm in diameter and, 15 mm in height. Dimorphic polyps are both yellow and white. Autozooids are large with long bodies. Siphoozooids are smaller. No sclerites in the polyps.

Description

The holotype of 40 mm × 20 mm is a combination of two orange, dome-shaped colonies linked by a, 5 mm spreading holdfast. The stalk is inconspicuous as the polyparium arises close to the holdfast. The two colonies are 18 and 22 mm in diameter and 17 and 15 mm in height. Because of the similar size of the two attaching colonies, it is impossible to distinguish the mother and daughter. That is, the specimen is close to its natural maximum size which is, 20 mm. Autozooids are 1.5 mm in diameter, yellow while retracted. Polyps long slender, white with a yellow base when extended. Siphonozooids are 0.5 mm when retracted. No polyp sclerites. All the sclerites are orange in water and densely distributed throughout the surface and interior of the colony. Sclerites from polyparium ( Figures 2 A–J) and stalk ( Figures 2 K–O) are variable. Polyparium sclerites composed of robust barrels with six-, seven- and eight-radiates, some appearing as double stars with elongated median waists. A transverse continuous groove appears on the waist of some sclerites ( Figures 2G, H ). One of the stalk sclerite types is cruciform with two central radiates perpendicular to the plane of the crucifix ( Figures 2K, L ). This shape is unique among species of Paraminabea . Others are robust, barrel-shaped with six-, seven- and eight-radiates and. Sclerite size, 0.05 to 0.09 mm in length.

Remarks

There are eight described species of Paraminabea . These are P. acronocephala ( Williams, 1992) , P. aldersladei ( Williams, 1992) , P. arborea Williams & Alderslade, 1999 , P. cosmarioides ( Williams, 1992) , P. goslineri ( Williams, 1992) , P. indica ( Thomson & Henderson, 1905) , P. kosiensis ( Williams, 1992) and P. robusta (Utonomi & Imahara, 1976) . The new species is distinguishable from all other Paraminabea species by its growth form, colony colour and sclerite shape. Paraminabea aldersladei , P. arborea , P. cosmarioidea , P. indica P. kosiensis and P. robusta have a digitiform growth form ( Williams 1992:4, Fig. 1 ; Williams and Alderslade 1999:346, Fig. 5A). Paraminabea arborea and P. indica may appear branched ( Williams and Alderslade 1999:346, 353, Fig. 5A, 10). Although P. acronocepala and P. goslineri both have a similar dome-shaped growth form and size range (3–20 mm) to the new species, the former has red retracted polyps whereas the latter is lemon yellow throughout the colony ( Williams 1992). In general, sclerite tuberculation in the other species are more thorny and robust than in the new species. The new species has cruciform sclerites with six radiates. This type of sclerite is absent in other species. Sclerite shape in the new species is different from that of P. cosmarioidea which has small, densely packed tuberculations. Paraminabea kosiensis has elongate spindles and P. robusta has large, robust tuberculations ( Williams 1992:11, 12, Fig. 7, 15).

Distribution

This uncommon genus is restricted to darker areas such as caves and overhangs at depths of, 10 m. It is distributed in the Indian Ocean from East Africa , Madagascar, Seychelles, Maldives and Sri Lanka to South East Asia including Hong Kong, the Philippines, Micronesia, Indonesia and the Indo Pacific , New Guinea, the Great Barrier Reef and localities in the South Pacific such as the

Solomon Islands and Fiji ( Fabricius and Alderslade 2001). The genus is a new record for Hong Kong.

Etymology

This is the first new species of Paraminabea recorded from Hong Kong and is thus named after the locality.

Figures

Figure 1. Living specimens of soft corals belonging to the Nephtheidae, Nidaliidae and Alcyoniidae. A, Scleronephthya pustulosa; B, Scleronephthya sp.; C, a dark red variety of Dendronephthya gigantea; D, a light pink variety of Dendronephthya gigantea; E, Nephthea chabrolii; F, Nephthyigorgia annectens; G, Paraminabea hongkongensis sp. nov. Scale bar52 cm.

Figure 2. Paraminabea hongkongensis sp. nov. Scanning electron micrographs of scletrites. A–E, polyparium sclerites. F–O, stalk sclerites. J and N are top views of the stalk sclerites.