Ophiactis savignyi ( Mueller & Troschel, 1842)

Gondim, Anne I., Alonso, Carmen, Dias, Thelma L. P., Manso, Cynthia L. C. & Christoffersen, Martin L., 2013, A taxonomic guide to the brittle-stars (Echinodermata, Ophiuroidea) from the State of Paraiba continental shelf, Northeastern Brazil, ZooKeys 307, pp. 45-96 : 61

Ophiactis savignyi ( Mueller & Troschel, 1842) Figure 8 g–l

Description.

Six arms. Disk circular (dd = 1.3 mm). Covered by numerous imbricating scales. Some small spines on scales at margin of disk (Fig. 8g). Radial shields large, triangular, contiguous (Fig. 8g). Ventral interradus with some spines on the scales (Fig. 8h). Bursal slit enlarged. Oral shields oval (Fig. 8i). Adoral shields widened laterally. One oral papilla on each side of jaw angle (Fig. 8i). Apical papilla well developed. Dorsal arm plate wider than long, sometimes subdivided into two plates (Fig. 8j). Ventral arm plate octogonal. Six arm spines, with denticles along margin and at tip (Fig. 8l). Single tentacle scale semi-elliptical (Fig. 8l).

Distribution.

Cosmopolitan, in warm waters throughout the western Indo-Pacific, eastern Pacific, including Malpelo Island off western coast of Colombia, and both sides of the Atlantic, including Ascension island in the South Atlantic. Western Atlantic from South Carolina, Bermuda, Mexican Caribbean, Honduras, and Brazil ( Devaney 1974, Pawson 1978, Hendler et al. 1995, Durán-Gonzáles et al. 2005, Cohen-Rengifo et al. 2009). In Brazil from Amapá, Pará, Maranhão ( Albuquerque 1986), Ceará ( Lima-Verde 1969), Paraíba ( Gondim et al. 2008), Pernambuco ( Tommasi 1970), Alagoas ( Miranda et al. 2012), Bahia ( Alves and Cerqueira 2000), Abrolhos off southern Bahia ( Tommasi 1970), Rio de Janeiro ( Brito 1960), and São Paulo ( Tommasi 1970). Intertidal to 518 m. Found at 10 m in this study.

Remarks.

Species found in all reef zones, seagrass beds, mangroves, and in contaminated communities ( Hendler et al. 1995). According to Madsen (1970), Ophiactis savignyi is very polymorphic, resulting in a vast synonymy. Juveniles are frequently found in large densities inside sponges, possibly as commensals ( Hyman 1955). Cuénot (1948) considers this behavior a case of pseudocommensalism, due to its marked positive stereotropism. Young forms (up to 4 mm in disk diameter) reproduce by fissiparity, although Devaney (1974) found no indications of this reproductive mode, while large specimens may reproduce both sexually and asexually ( Tommasi 1970). Gondim et al. (2008) observed that they may live permanently in phytal communities, in which several life stages were found.