Amphinema australis (Mayer, 1900)

Buecher, Emmanuelle, Goy, Jacqueline, J, Mark & Gibbons, 2005, Hydromedusae of the Agulhas Current, African Invertebrates 46, pp. 27-69 : 41

Amphinema australis (Mayer, 1900)

Stomotoca australis: Mayer 1900 b: 32 , pl. 1, fig. 2.

Amphinema australis: Kramp 1961: 92 ; 1968: 42, fig. 107.

Description: Two specimens from two stations. Essentially bell-shaped umbrella, as broad as tall but with pronounced, solid apical projection; up to 3.3 mm in height. Exumbrella surface smooth. Mesoglea thickened apically. Velum broad. Peripheral canal and four broad radial canals present; no centripetal canals or mesenteries. Two opposite perradial tentacles arising from umbrella margin, long, hollow. Secondary tentacles absent but 4–5 marginal warts present, 1–2 per quadrant. Manubrium urn-shaped, extending to half bell depth. Mouth simple, with four prominent, recurved lips; without gastric peduncle. With orange-red ocelli at base of tentacles and warts. Gonads interradial, folded, not extending along radial canals.

Material examined: H5017.

Comments: Ten recognised species (Bouillon & Boero 2000 b), of which three have been described previously from this region (Kramp 1961). Species can generally be distinguished by the number of secondary tentacles or marginal warts and the shape of the manubrium, as well as by the presence, and colour, of ocelli. The distribution of the gonads can also be important. The species that is not described here, but which has been recovered from the west Indian Ocean previously (Bouillon 1978 b) is A. dinema ( Péron & Lesueur, 1810) , and it can readily distinguished by the fact that it has 14–24 marginal warts (3–6 per quadrant), a flask-shaped manubrium that is cruciform in section, and lacks ocelli. A. rugosum (Mayer, 1900) has been collected off the Seychelles (Bouillon 1978 b).

Distribution: Widely distributed in tropical and subtropical waters of the Atlantic and Pacific oceans. This is the first record from the west Indian Ocean. Neritic.