Ophiactis Lütken, 1856

Alitto, Renata A. S., Bueno, Maristela L., Guilherme, Pablo D. B., Domenico, Maikon Di, Christensen, Ana Beardsley & Borges, Michela, 2018, Shallow-water brittle stars (Echinodermata: Ophiuroidea) from Araçá Bay (Southeastern Brazil), with spatial distribution considerations, Zootaxa 4405 (1), pp. 1-66 : 49

Genus Ophiactis Lütken, 1856

Type taxon. Ophiactis savignyi ( Müller & Troschel, 1842) originally described as Ophiolepis savignyi .

Diagnosis. Circular, with scales dorsally and ventrally. Mouth angles small and narrow. One to four lateral oral papillae, usually one. Six arms, sometimes five or seven. One tentacle scale. Three to six arm spines, frequently denticulate ( Tommasi 1970; Albuquerque 1986).

Comments. Ophiactis differs from Hemipholis in that there are scales on both sides of the disc and three to six denticulate arm spines, whereas Hemipholis only has three, without denticles. Arms and disc are often observed to differ in size on the same individual ( Tommasi 1970; Manso et al. 2008), due to high rates of fission and regeneration ( Hendler et al. 1995). Ophiactis presently includes 51 species ( Stöhr et al. 2016), five of which have been recorded from Brazil ( Barboza & Borges 2012): O. brasiliensis Manso, 1988 , O. lymani Ljungman, 1872 , O. muelleri Lütken, 1856 , O. quinqueradia Ljungman, 1872 and O. savignyi ( Müller & Troschel, 1842) .