Hybocodon unicus ( Browne, 1902 )

Buecher, Emmanuelle, Goy, Jacqueline, J, Mark & Gibbons, 2005, Hydromedusae of the Agulhas Current, African Invertebrates 46, pp. 27-69 : 49

Hybocodon unicus ( Browne, 1902)

Amphicodon unicus: Browne 1902: 276 .

Hybocodon unicus: Kramp 1961: 44 ; 1968: 13, fig. 20.

Description:Two specimens from two stations. Bell-shaped umbrella, taller than broad, with indistinct apical projection; up to 2 mm in height. Umbrella margin slightly oblique. Exumbrella surface smooth, with irregularly scattered cnidocyst tracks. Mesoglea thinning laterally. Velum broad. Peripheral canal and four narrow radial canals present, latter with smooth margin; with neither centripetal nor apical canals. With four perradial marginal bulbs; three minute and rudimentary, fourth surrounded by cnidocyst swellings; latter bulb forming base of single tentacle. Tentacle long, typically coiled, hollow, unbranched, filiform. Manubrium cylindrical, not extending beyond velum, not connected to radial canals by mesenteries. Mouth simple, circular, without lips; on short gastric peduncle. Without ocelli on bulb of marginal tentacles. Gonads simple, entirely encircling manubrium for much of length.

Material examined: H5043, H5044.

Comments: Five free-living medusae are recognised as valid by Bouillon and Boero (2000 b), though aside from the present material, none are known from the west Indian Ocean. Species can be separated on the distribution and number of cnidocyst tracks on the exumbrella, the number and structure of marginal tentacles and the relative size and shape of the manubrium.

Distribution: Widespread and scattered in Indian and south-west Atlantic oceans. This is the first record from the west Indian Ocean, though previously recovered from India ( Ganapati & Nagabhushanam 1958). Neritic.