Zygocanna buitendijki Stiasny, 1928

Buecher, Emmanuelle, Goy, Jacqueline, J, Mark & Gibbons, 2005, Hydromedusae of the Agulhas Current, African Invertebrates 46, pp. 27-69 : 53

Zygocanna buitendijki Stiasny, 1928

Zygocanna buitendijki: Stiasny 1928: 218–224 , figs 5, 6; Kramp 1961: 210; 1968: 101, fig. 275.

Description: Six immature specimens from single station. Umbrella as flattened hemisphere, much broader than tall, without apical projection; 1.9 mm in diameter. Exumbrella surface with numerous, relatively indistinct radiating ribs; without gelatinous papillae. Mesoglea thickened centrally, thinning to margin. Velum narrow. Peripheral canal and 16 radial canals present, latter narrow, with smooth margin; much branched; without centripetal canals. With 16 tentacles connected to peripheral canal, arising from small heart-shaped bulbs on umbrella margin. Tentacles of similar size, long, hollow, unbranched, filiform. Without small rudimentary bulbs or secondary tentacles.All marginal bulbs without either lateral extensions or keel, excretory papillae present. Lateral and marginal cirri absent. Manubrium up to 1/2 umbrella width, broad and flat, not extending to velum, not connected to radial canals by mesenteries. Mouth simple, circular, without lips; gastric peduncle absent. Statocysts closed, numerous. Without ocelli. When mature, gonads extending along distal portion of radial canals, but not reaching peripheral canal.

Material examined: H5051.

Comments: Although species of Zygocanna appear to be largely confined to the Indo-Pacific, only one other has been recorded from the region – Z. vagans Bigelow, 1912 , off the Cape of Good Hope (Kramp 1957, 1965). Species can be differentiated by the number of ribs or papillar rows on the exumbrella surface, the number of radial canals and their degree of branching. The present material lacked marginal bulbs (as Bouillon 1984: 25), but is clearly recognisable by the small number of marginal tentacles and large number of radial canals.

Distribution: Indo-Malayan area. This is the first record from the west Indian Ocean, though it has been recorded along the coast of India (see records in Kramp 1961). Neritic.