Asterina, Nardo, 1834

Rowe, Frank & Richmond, Matthew, 2004, A preliminary account of the shallow-water echinoderms of Rodrigues, Mauritius, western Indian Ocean, Journal of Natural History 38 (23), pp. 3273-3314 : 3287-3290

‘ Asterina ’ sp. 2

Material. One specimen (five arms), Rivière Banane, in algae; one specimen

(six arms), Antonio’s Finger Reef, on dead coral, 9 m; four specimens (one with five arms, three with six arms), Antonio’s Finger Reef, off Grand Baie; one specimen (juvenile,?six arms), Passe Coco, under rubble, 6 m; one specimen (six arms), Trou Malabar, under rubble, 10 m; 10 specimens (five with five arms, five with six arms), Ile aux Fous, on coral and among coralline lumps.

Coloration. Predominantly red or with some cream/white mottling (see figure 5 ).

Comments. Of the 18 specimens examined from Rodrigues, seven have five arms and 11 have six arms. They range in size from the largest five-armed specimens with R ~ 7.5 mm, r ~ 3.6 mm (one arm is regenerating and measures approximately R ~ 4 mm) to the smallest, six-armed specimens with arm lengths ranging between R ~ 1.8 and R ~ 3.2 mm. The largest, five-armed specimen ( R ~ 7.5 mm) has two madreporites, though the madreporites have yet to be detected in the smaller specimens. The most consistent character exhibited by all these specimens is the occurrence of only a single sub-oral spine on each of the oral plates. In this character alone the Rodrigues specimens differ from all other described, fissiparous, tropical Indo-west Pacific species included in the genus ‘ Asterina ’ [i.e. burtoni (Gray, 1840) (with synonym wega (Perrier, 1869) ; anomala H. L. Clark, 1921 ; hexactis H. L. Clark, 1938 and coralicola Marsh, 1977] and we therefore do not consider the present specimens to be conspecific with the supposedly sympatric ‘ A. ’ burtoni (which we now doubt occurs in the local region).

On the basis of a specimen collected by one of us ( M.D. R.) from Zanzibar (recorded in Rowe and Richmond, 1997, 2002, under the mantle name of Asterina burtoni ) and some 24 specimens from Réunion sent to F. W. E. R. by Dr Chantal Conand (identified as Asterina burtoni ), we conclude that these specimens and the Rodrigues specimens are conspecific and thus that ‘ Asterina ’ sp. 2 occurs at least in the Mascarene Islands and on the east coast of Africa. Interestingly, the specimen from Zanzibar and seven specimens from Réunion have seven arms, a character not yet seen in specimens from Rodrigues. These specimens also differ in colour from the Rodrigues material in being more varied in colour and finely mottled ( C. Conand, personal communication).

Distribution. Rodrigues, Réunion, Zanzibar (East Africa); 0– 10 m.

Family ECHINASTERIDAE

Echinaster purpureus (Gray, 1840)

See: Clark and Rowe, 1971: 40 (distribution), 73 (key).

Material. Two specimens (R to 80 mm, r to 11.3 mm), Grand Baie, lagoon, low tide, common.

Coloration. Pale creamy pink or brown with fine, darker mottling.

Comments. Both specimens have sustained damage to one arm, which are showing signs of regeneration.

Distribution. Endemic to the Indian Ocean.

Class OPHIUROIDEA Family GORGONOCEPHALIDAE Astrocladus tonganus Doderlein, 1911 See : Clark and Rowe, 1971: 78 (distribution), 92 (key); Cherbonnier and Guille

1978: 14.

Material. One specimen (d.d. ~ 18 mm), Totor Reef (night-time, 19:00 h), 0.6 m, among coral. Two specimens deposited at the Shoals Rodrigues office.

Coloration. Live animals pale pink-yellow showing slight banding on main arms; entire animal becoming darker purple following collection, anaesthetization and preservation.

Comments. On the basis that the arm spines occur distally between the second and third fork of the arms and certainly immediately after the third fork, the specimen examined herein conforms satisfactorily to the genus Astrocladus and to A. tonganus according to both Clark and Rowe (1971: 92) and Cherbonnier and Guille (1978: 10–11). This new record thus confirms the latter’s first record of this otherwise south-western Pacific Ocean species in the western Indian Ocean at Madagascar. The more widespread species Astroboa clavata (Lyman, 1861; type locality Zanzibar) and A. nuda (Lyman, 1874; type locality Philippines), each of which have been recorded in the western Indian Ocean (see Clark and Rowe 1971: 78–79) are distinguished generically by the absence of arm spines before the fourth arm fork. Several specimens were observed at the collection site, but not collected.

Distribution. A new record for the Mascarene Islands, adding to the only other records for the species from Madagascar and Tonga.

Family OPHIOMYXIDAE

Ophiomyxa australis Lutken, 1869

See: Clark and Rowe, 1971: 78 (distribution), 92 (key); Cherbonnier and Guille, 1978: 18.

Material. One specimen (d.d. ~ 10 mm, a.l.:d.d. ~ ca 3:1), Rivière Banane, under rock (basalt), mid-upper shore, near beach.

Coloration. Disc uniformly orange-red, with small black dots; arms banded red and pink.

Comments. Only a single specimen was found.

Distribution. This distinctive species described from Bass Strait (between south-eastern mainland Australia and Tasmania) not only circumscribes Australia (see Rowe and Gates, 1995) but extends, more or less, throughout the Indowest Pacific region in shallow waters, but recorded to depths of over 1000 m! It is notably absent from Hawaii to the east and in the western extreme of the region, from the north-west Indian Ocean (Arabian coast, Arabian Gulf and Red Sea), including the west coast of India.

Family OPHIACTIDAE

Ophiactis savignyi Müller and Troschel, 1842

See: Clark and Rowe, 1971: 82 (distribution), 103 (key); Cherbonnier and Guille, 1978: 125.

Material. One specimen, Grand Baie, dead coral rock on spurs, 17–19 m; three specimens, Graviers; one specimen, Ile aux Fous, Blue Holes, among coral, 2 m.

Coloration. Live specimens pale green and dark green (almost black); disc pale pink with dark green mottling.

Comments. The five specimens exhibit an interesting range of morphological characters for which this polymorphic, tropicopolitan species is renowned (see Clark and Rowe, 1971; Cherbonnier and Guille, 1978). The specimens range in size with d.d. ~ 1.4–4.8 mm and a.l:d.d. ~ ca 2–2.5:1. The smallest specimen has a single, peg-like oral papilla and four proximal arm spines; two specimens, with d.d. ~ 2.4 mm and 4.4 mm, each have two oral papillae and six proximal arm spines. The remaining two specimens, with d.d. ~ 2.4 mm and 4.8 mm, each have three oral papillae—a condition noted for a specimen from the Mediterranean by Guille (1968). The smaller of these last two specimens has five proximal arm spines whereas the larger specimen has not only have seven arm spines, but the dorsal arm plates from about 5–17 are longitudinally divided, a condition not hitherto recorded for the species. There is little doubt that this small, fissiparous species, originally described from Red Sea specimens, would benefit from an investigation using molecular analysis, which should help unravel the relationship between O. savignyi (s. s.) and the host of subsequently described species currently considered conspecific with it.

Distribution. Tropicopolitan.

Family AMPHIURIDAE

Amphiodia (Amphiodia) dividua (Mortensen, 1933)

See: Clark and Rowe, 1971: 78 (distribution), 99 (key); Cherbonnier and Guille, 1978: 92; Sloan et al., 1979: 101.

Material. One specimen, Chaland Reef, among sediment.

Comments. This six-armed specimen accords well with the detailed description for the species given by Cherbonnier and Guille (1978).

Distribution. The type locality for the species is Mauritius; now known from Aldabra, Madagascar, Mauritius and Rodrigues.

Amphipholis squamata (D. Chiaje, 1829)

See: Clark and Rowe, 1971: 80 (distribution), 99 (key).

Material. Two specimens, Ile aux Fous, Blue Holes, in sand, 6 m; one specimen, Graviers , in sand in rock pool ; one specimen, Anse aux Anglais, sand/ stone sieving ; one specimen Coton Baie beach, rocks, near hotel ; six specimens, Petite Butte , among green alga Cladophoropsis , lower shore on calcareous rock ; four specimens, Trou Malabar , Mathurin Bay, semi-mobile sand subtidal in gully ; one specimen, Chaland Reef , in sediment .

Coloration. White.

Comments. Widely present among various habitats, the occurrence of this ubiquitous, yet small (v 3 cm), species on Rodrigues was to be expected.

Distribution. A new record for the Mascarene Islands.

Figures

FIGS 2–16. (2) Stephanometra indica (# RGS/Jeremy Neech). (3) Gomophia watsoni (# RGS/Jeremy Neech). (4) ‘Asterina’ sp. 1. (M. Richmond). (5) ‘Asterina’ sp. 2. (M. Richmond). (6) Ophiocoma brevipes (# RGS/Jeremy Neech). (7) Ophiocoma dentata (# RGS/Jeremy Neech). (8). Microcyphus maculatus (M. Richmond). (9) Bohadschia sp. 1 (M. Richmond). (10). Bohadschia sp. 2 (# RGS/Jeremy Neech). (11)?Bohadschia sp. 3 (# RGS/Jeremy Neech). (12) Holothuria impatiens s. s. (# RGS/Jeremy Neech). (13) Holothuria impatiens bicolor. (# RGS/Jeremy Neech). (14) Holothuria impatiens concolor. (# RGS/Jeremy Neech). (15) Psolidium ornatum (# RGS/Jeremy Neech). (16) Plesiocolochirus dispar (# RGS/Jeremy Neech).