Blackfordia virginica Mayer, 1910

Buecher, Emmanuelle, Goy, Jacqueline, J, Mark & Gibbons, 2005, Hydromedusae of the Agulhas Current, African Invertebrates 46, pp. 27-69 : 54

Blackfordia virginica Mayer, 1910

Blackfordia virginica: Mayer 1910: 277 , pl. 36, figs 3–5; Kramp 1961: 181; 1968: 85, fig. 228.

Description: Single specimen. Domed umbrella, slightly taller than broad, without apical projection; 4 mm in diameter. Exumbrella surface smooth. Mesoglea thick, thinning to margin. Velum narrow. Peripheral canal and four radial canals present, latter narrow, with smooth margin and unbranched; without centripetal canals. With approx. 100 tentacles connected to peripheral canal, arising from small bulbs on umbrella margin. Endoderm of tentacles extend inwards to mesoglea at margin. Tentacles of similar size, long, hollow, unbranched, filiform. With no atentaculate marginal bulbs. All marginal bulbs without keel, and with neither excretory pores nor excretory papillae. Lateral and marginal cirri absent. Manubrium narrow, short, not extending to velum, not connected to radial canals by mesenteries. Mouth simple, circular, with four slightly recurved, crenulated lips; gastric peduncle absent. Statocysts closed, one between each marginal tentacle. Without ocelli. Gonads linear, sinuous, completely surround radial canals, rarely extending more than half radial canal length.

Material examined: H5052.

Comments: Three named species are recognised by Bouillon and Boero (2000 b). They differ in the distribution of their gonads, and in the number and structure of their statocysts. The other two species have not, to date, been recovered from the Indian Ocean.

Distribution: Widespread in temperate and subtropical waters, including coastal Brazil ( Paranaguá 1963), Mediterranean Sea and Black Sea. A known invasive species into North America ( Mills & Rees 2000) and India ( Carlton 1985). This is the first record from the west Indian Ocean. Neritic.