Ophiothrix (Ophiothrix) savignyi ( Müller & Troschel, 1842 )

Fatemi, Yaser & Stöhr, Sabine, 2019, Annotated species list of Ophiuroidea (Echinodermata) from the Persian Gulf and Gulf of Oman, with new records, Zootaxa 4711 (1), pp. 77-106 : 86-87

Ophiothrix (Ophiothrix) savignyi ( Müller & Troschel, 1842)

Fig. 5

Ophionyx savignyi Müller & Troschel, 1842: 117 .

Material examined: Persian Gulf, Iran, Bustaneh, intertidal, on gorgonians ( Subergorgia suberosa (Pallas, 1766) , hand collected Yaser Fatemi, 30 spms, 4.5 mm to 7.2 mm dd [SMNH-178933].

Habitat: Subtidal rock, subtidal sand, mixed subtidal rock and sand, subtidal mud, Coral reef, Artificial structure, sand tidal flat, rock tidal flat, rock and sand beach, 0–33 m ( Mortensen 1940; Clark & Bowen 1949; Price 1981, 1983; Jones 1986; present study) ( Fig. 2B ).

Persian Gulf and Gulf of Oman: Kuwait, Bahrain, Chiruyeh (6), Kish Island (7), Jubail (19), Abu Ali (20), Jinna Island (21), Al Juraid Island (22), Ras Tanura (24), Tarut Bay (25), Dammam Channel (26), Stiffe’s Bank (28), As Saffaniyah (32), Bustaneh (34) (ibid.).

Indian Ocean: Tanzania ( Ludwig 1899), Mascarene Basin and Red Sea ( Clark & Rowe 1971), Chagos Isl. ( Clark & Taylor 1971), Madagascar ( Cherbonnier & Guille 1978), Kenya ( Humphreys 1981).

Remarks: Ophiothrix savignyi is a smaller species with a disc diameter less than 10 mm ( Cherbonnier & Guille 1978) and arms about five times the disc diameter long ( Price 1983). Price (1983) remarked on the extremely variable coloration of this species, and our samples seem to confirm this observation. Live animals collected by the present study are brown, uniform or with lighter spots on the disc and irregular white patches or bands along the arms ( Fig. 5A, F, G ). There is a median line along each arm, which may be pale cream ( Fig. 5G ) or bright red ( Fig. 5A, F ). It is often bordered by two thin dark lines ( Fig. 5E ) but these may be absent, and then the median red line may be wider ( Fig. 5A ). In alcohol, the animals turn blue to dark purple and the red line turns white ( Fig. 5B, D, G, K, L ). They have longer (> 1 mm), rod-like, slightly serrated spines on the dorsal disc and shorter trifid stumps (<0.2 mm) in variable density ( Fig. 5E ). The dorsal arm plates are barely wider than long, rhombic and with a median ridge that extends slightly beyond the distal border.

This is the only species of Ophiothrix that has so far been reported from the Persian Gulf and Gulf of Oman. It is extremely similar to Ophiothrix ciliaris ( Lamarck 1816) , of which Koehler (1922) figured several specimens (under the younger synonym Ophiothrix stelligera Lyman, 1874 ) with variable color pattern that showed longitudinal lines on the arms as in Ophiothrix savignyi . Clark (1938) remarked for O. ciliaris that the median line is always white on the distal arm in animals with red or dark lines. In our specimens, the lines do not change color along the length of the arms. Both species also share a variable disc covering with predominantly trifid stumps, sometimes mixed with long spines ( Koehler 1922; Mortensen 1926). A distinguishing character may be the shape of the ventral arm plates, which have a strongly concave distal edge in Ophiothrix savignyi but are straight in O. ciliaris ( Clark & Rowe 1971) . This is visible in O. ciliaris on pl. 53, figs 3, 6 and pl. 54, fig. 6 in Koehler (1922) and in Ophiothrix savignyi on pl. VI fig. 6 in Cherbonnier & Guille (1978), but was not considered an important character by those authors, probably because none of them compared O. ciliaris to Ophiothrix savignyi . Indeed, we have not been able to find a taxonomic study that compared these two species, despite their striking similarity. In addition, Ophiothrix savignyi usually has minute thorns on the dorsal arm plates ( Clark & Rowe 1971; Guille & Wolff 1984), which may however be absent ( Price 1983). Our specimens lack these thorns but have concave ventral arm plates ( Fig. 4C ). Müller & Troschel (1842) described Ophiothrix savignyi (in genus Ophionyx ) as having keeled, almost rhombic dorsal arm plates and concave ventral arm plates Rückenschilder der Arme gekielt, von fast rhombischer Gestalt. Bauchschilder der Arme breiter als lang, am aboralen Rande ausgeschweift, am adoralen abgerundet. (p. 117). This description concurs with our specimens. The type locality of Ophiothrix savignyi was given as Egypt ( Müller & Troschel 1842), presumably Red Sea, not Mediterranean Sea, whereas Lamarck (1816) referred O. ciliaris to Australia. Considering the wide geographical distance between both species and the fact that the Indian Ocean specimens have been assigned to Ophiothrix savignyi by all previous authors, we place our specimens in that species. It is obvious that a taxonomic revision is needed and morphological characters alone may not provide a satisfying answer.

Attaran-Fariman et al. (2016) reported O. savignyi from the Gulf of Oman at Tis port, but the figured animal lacks long disc spines, has few or no disc stumps, dorsal arm plates that are about twice as wide as long and seem to be rugose. All of these characters and its size of about 15 mm dd suggest that it is Macrophiothrix hirsuta cheneyi instead. Records of Ophiothrix savignyi from the Andaman and Nicobar Islands by Sadhukhan et al. (2012) are based on a misidentified hexamerous Ophiothela , possibly O. danae (likewise all other records in that publication are based on misidentifications).

Figures

FIGURE 2. Habitats at the sites where brittle stars were collected by the present study (see Table 1). A, Bandar Lengeh, B, Bustaneh, C, Chabahar Bay (Hotel Lipar), D, Chabahar Bay (University coast), E, Chabahar Bay (Tis), F, Qeshm Island.

FIGURE 4. Live photos of Ophiocomella sexradia [SMNH-178932], Persian Gulf, Qeshm Island. A, dorsal aspect, B, ventral aspect, C, dorsal disc, D, oral frame, E, dorsal arm, F, ventral arm.

FIGURE 5. Color morphs of Ophiothrix savignyi [SMNH-178933], Persian Gulf, Bustaneh. A, live photo, dorsal aspect, note the wide red line along the arms and the absence of dark border lines, B–E, same animal, preserved in ethanol, the brown disc is grey-blue, the red line is white, B, dorsal aspect, C, ventral aspect, D, dorsal arm, E, disc spines, F, live photo, dorsal aspect, along arms a narrower red line with thin dark borders, G, H, same animal, preserved in ethanol, the brown disc has changed to dark blue, the red line has turned white, G, dorsal aspect, H, dorsal arm, I, J, live photos, brown animal with white line along arms, bordered by thin blue lines, I, dorsal aspect, J, ventral aspect, K, L, same animal preserved in ethanol, brown has turned to blue.