Eirene menoni Kramp, 1953

Buecher, Emmanuelle, Goy, Jacqueline, J, Mark & Gibbons, 2005, Hydromedusae of the Agulhas Current, African Invertebrates 46, pp. 27-69 : 54-55

Eirene menoni Kramp, 1953

Eirene menoni: Kramp 1953: 286 , pl. 2, fig. 6; 1961: 189; 1968: 90, fig. 242.

Description: Ten specimens from five stations. Hemispherical, domed umbrella, slightly taller than broad, without apical projection; up to 10 mm in diameter. Exumbrella surface smooth. Mesoglea thick, thinning to margin. Velum narrow. Peripheral canal and up to six radial canals present, radial canals narrow, with smooth margin, unbranched, extending from umbrella margin across underside of bell and along gastric peduncle to manubrium; without centripetal canals. With up to 30 tentacles connected to peripheral canal, arising from swollen bulbs on umbrella margin. Tentacles generally short, slender, 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 short, not connected to radial canals by mesenteries. Mouth simple, with four slightly recurved, crenulated lips; gastric peduncle pronounced, narrow, with conical base. Statocysts closed, numerous. Without ocelli. Gonads linear, may be sinuous, variably extending along subumbrella surface of radial canals.

Material examined: H5053.

Comments: Eighteen species are currently considered to be valid (Bouillon & Boero 2000 b). Excluding the currently described material, three other species have been recorded from the west Indian Ocean, including E. ceylonensis Browne, 1905 (off Natal – Kramp 1965), E. palkensis Browne, 1905 (off Natal – Vanhöffen 1912) and E. hexanemalis (Goette, 1886) (Kramp 1965; Millard 1975; Bouillon 1978 b). A further four are known from elsewhere in the Indian Ocean: E. elliceana (Agassiz & Mayer, 1902) , E. kambara Agassiz & Mayer, 1899 , E. pyramidalis (L. Aggassiz, 1862) and E. tenuis (Browne, 1905) . Species of Eirene can be distinguished (with difficulty) on the shape and consistency of their umbrella, the size and shape of the gastric peduncle, and the number and length of the marginal tentacles and atentaculate marginal bulbs. The number and shape of oral lips can also be important, as can the presence/absence of excretory papillae/pores associated with tentacle bulbs. E. hexanemalis is identifiable by its somewhat flattened umbrella and the presence of up to six radial canals (and oral lips); the gastric peduncle is pronounced, thick, with conical base. It also has between 30–50 short tentacles that arise from large, swollen bulbs with excretory papillae. E. palkensis possesses three times as many atentaculate than tentaculate marginal bulbs, all of which have obvious excretory papillae. Specimens have up to 50 tentacles and the gonads extend along almost the entire length of the radial canals from the gastric peduncle. E. ceylonensis is characterised by its slender gastric peduncle and elongated gonads that extend from the manubrium to the umbrella margin. This species also has few atentaculate marginal bulbs, pronounced excretory papillae and more than 100 marginal tentacles.

Distribution: Widespread in tropical and subtropical waters of the Indo-West Pacific. Previously collected from along the coast of south-east Africa (Kramp 1965; Millard 1975). Neritic.