Ophiactis savignyi

Boissin, Emilie, Hoareau, Thierry B., Paulay, Gustav & Bruggemann, J. Henrich, 2016, Shallow-water reef ophiuroids (Echinodermata: Ophiuroidea) of Réunion (Mascarene Islands), with biogeographic considerations, Zootaxa 4098 (2), pp. 273-297 : 278

Ophiactis savignyi MÜLLER & TROSCHEL, 1842

(UF-6463, Fig. 2 d, GU480578 )

Material. 2 spms, St. 2; 4 spms, St. 5

Remarks. max DD in Reunion Island: 2.62 mm ( Stöhr et al. 2008). The specimens have six arms, two distal oral papillae and the dorsal arm plates are elliptical with a small median distal lobe. Radial shields are large and their length is about half the radius. There are five to six spines on the proximal segments then four spines along the rest of the arm. The colouration is variegated green and white. O. savignyi is common among algae, in coral crevices, and sponges. Specimens from St. 2 were found on the coral Stylocoeniella guentheri , while those from St. 5 were found in the sponge Spheciospongia . All specimens show evidence of fissiparity, a common mode of asexual reproduction for this species. Ophiactis savignyi shows limited genetic differentiation in mtDNA within the Indo-Pacific and is best considered a single species ( Roy & Sponer 2002).

Abundance: 3.

Distribution. Known from the Atlantic and the Indo-Pacific; previously recorded from Réunion ( Guille & Ribes 1981; Stöhr et al. 2008) and Rodrigues ( Rowe & Richmond 2004).

Ophiactis picteti ( DE LORIOL, 1893) (REU-3733)

Material. 1 spm, St. 7

Remarks. A five-armed species, much bigger (DD: 8 mm) than O. savignyi (max DD in Reunion island: 2.62 mm, Stöhr et al. 2008), with two distal oral papillae and six arm spines along the length of the arm. The overall colouration is pale brown. Among the 11 shallow IWP Ophiactis species, only four have two oral papillae. The colouration, size of the adoral shields and length of the arms (~ 6DD), of our specimen are consistent with O. picteti . The specimen was found in a crevice of the fire coral Millepora platyphylla . Abundance: 1.

Distribution. Described from the Amboina ( Moluccas, de Loriol 1893b), it has also been recorded from Mozambique ( Balinsky 1957); Aldabra ( Sloan et al. 1979) and Madagascar ( Cherbonnier & Guille 1978). This is a first record for Réunion and the Mascarene Islands.

Figures

FIGURE 2. Pictures of species encountered in Réunion Island waters. Pictures were taken of freshly collected specimens except when indicated. Photo credit: BIOTAS.