von Lendenfeld, 1884
A medium-sized medusa slightly flatter than a hemisphere when mature, brown with conspicuous white spots, mouth-arms large, bushy. Bell diameter to 50 cm, surface finely granular, shallowly grooved radially between lappets; jelly thick, firm but flexible, to ca. 50 mm. Subumbrella with numerous filaments, gastrula-stage embryos adhering between them. Subgenital ostia oval, more than twice width of pillars between. Marginal lappets typically in each octant 4 truncate or notched ones centrally, flanked on each side by two narrower pointed ones and a single rhopalar lappet on each side; the central lappets partly fused basally by membranous web. Rhopalia 8. Circular subumbrellar muscle fields interrupted over radial canals. Mouth-arms J-shaped, 8, 3-bladed, 2/3 longer than bell diameter; the 3 leaves bearing mouthlets, pinnately branched but shallowly; distally bearing blunt, tapering filaments, extensile up to length of mouth-arm. Stomach cross-shaped; radial canals 8, connected subdistally by circular canal; peripheral to circular canal, a finely anastomosed network connecting radial canals and extending into lappets; centripetally, a similar zone connecting with the 4 perradial radial canals and the stomach, but not with the interradial canals.
Coloration: jelly of umbrella clear except for many embedded yellowish-brown zooxanthellae sub-epidermally giving pale to mid-brown color to bell (? to greyish-blue), darkest peripherally; also many groups of minute refractive whitish bodies giving spotted appearance; mouthlet regions deep brown, filaments colorless.
Formerly probably just Indo-Pacific, spread to isolated North and South Atlantic localities by introductions, some persisting several years; several South American records.
Remark: Mastigias scintillae Soares Moreira (1961) is conspecific.
(Partly after Mayer, 1910).