Olindias phosphorica (Delle Chiaje, 1841)

Fig. 114 A, B

See Kramp (1961) for a complete synonymy.

Material examined. HCUS-S 124 (Hydrozoa Collection, University of Salento—fauna of the Salento Peninsula)—medusa stage.

Description (based on our own observations; Delle Chiaje 1841 and Mayer 1910 both as Oceania phosphorica; Kramp 1959):

Hydroid. Solitary polyps, small, enclosed in a cylindrical or irregularly curved hydrothecae covering more than half hydranth length, much longer than the polyp itself; mouth distal surrounded by large cnidocysts; without tentacles.

Medusa. Umbrella almost hemispherical, 40–60 mm wide, mesoglea fairly thick; with 4 straight radial canals, 11–19 centripetal canals per quadrant; gonads variable in size, on sides of the radial canals and bearing characteristic papilliform processes; with 2 tentacle types: 30–60 primary tentacles, issuing above bell margin, with distal adhesive pads and batteries of nematocysts in transverse clasps; 100–120 secondary tentacles on bell margin, without adhesive pads; 100–170 marginal clubs; usually 2 statocysts at base of each primary tentacle. Colours: mesoglea transparent, radial canals reddish, tentacles blue to burgundy.

Cnidome Microbasic euryteles (hydroid); atrichous isorhizas, microbasic mastigophores and microbasic euryteles (medusa)

Seasonality. June–November (see Bouillon et al. 2004); June–October in Salento waters (this study).

Reproductive period. Since the polyp of O. phosphorica has not been found in nature, we have no reliable information on the reproductive period of this species.

Distribution. Atlantic and Mediterranean (Bouillon et al. 2004).

Records in Salento. S. Foca, Porto Badisco, Campomarino, Vernole, S. Cataldo, Otranto, Nardò, Manduria, Porto Cesareo, Torre dell’Orso, Melendugno, Gallipoli, Torre Lapillo, Torre Specchia Ruggeri (this study); coast of Salento (De Donno et al. 2014).

Remarks. The polyp stage of this species has not been found in the field yet. It was described by Weill (1936) from laboratory observations and very little is known about its behavior and ecological traits. O. phosphorica shows a peculiar feeding behavior in which, after a period of rest on the bottom, the medusa starts pulsating vigorously and rises to the surface, only to let itself sink again with the tentacles expanded in order to capture planktonic organisms.

References. Delle Chiaje (1841), Graeffe (1884) and Lo Bianco (1909) as Olindias mülleri; Mayer (1910), Babic (1913c), Neppi & Stiasny (1913), Neppi (1919), Caziot (1921), Zirpolo (1932) as O. mülleri, Picard (1951c, 1952, 1955), Micallef & Evans (1968), Rossi (1971), Goy (1973), Berdar & Cavallaro (1980), Brinckmann-Voss (1987), Riedl (1991), Medel & López-González (1996), Bouillon et al. (2004), Touzri et al. (2004a, b), Zakaria (2004), De Donno et al. (2014).