Amphinema dinema (Péron and Lesueur, 1810), Peron and Lesueur, 1810

Gravili, Cinzia, Vito, Doris De, Camillo, Cristina Gioia Di, Martell, Luis, Piraino, Stefano & Boero, Ferdinando, 2015, The non-Siphonophoran Hydrozoa (Cnidaria) of Salento, Italy with notes on their life-cycles: an illustrated guide, Zootaxa 3908 (1), pp. 1-187 : 44-45

Amphinema dinema (Péron and Lesueur, 1810)

Fig. 29 A, B

See Schuchert (2007) for a complete synonymy.

Material examined. HCUS-S 0 34 (Hydrozoa Collection, University of Salento—fauna of the Salento Peninsula)—polyp stage.

Description (based on our own observations; Rees & Russell 1937; Russell 1953; Schuchert 2007, 2012):

Hydroid. Hydrorhiza as creeping stolons; colony stolonal; hydrocaulus longer than hydranth, unbranched, covered by thin perisarc, often covered by detritus, extending to the base of the hydranth, distal perisarc margin indistinct, basal perisarc with or without annulations; hydranths fusiform, hypostome rounded-conical; with 8–14 amphicoronate filiform tentacles in one whorl; medusa buds ovoid to pyriform, enclosed in thin perisarc membrane, borne singly on short pedicel arising from hydrorhiza. Colour: hydranth bright orange-red.

Habitat type. Posidonia , depth range 0.5– 20 m ( Boero 1981a, b; Boero & Fresi 1986), and on several substrates.

Substrate. Eudendrium glomeratum (Hydrozoa) , Sertularella crassicaulis (Hydrozoa) , Cellaria fistulosa (Bryozoa) and dead colonies of Bryozoa, gorgonians, Posidonia rhizomes, algae, sponges, barnacles.

Seasonality. In the Mediterranean Sea from January to December ( Boero & Fresi 1986; this study).

Reproductive period. In the Tyrrhenian Sea ( Brinckmann-Voss 1987), fertile colonies occur from May to August.

Medusa. Adult. Bell slightly higher than wide, up to 4 mm wide and 6 mm high, mesoglea of uniform thickness besides top, with a large, conical, solid, apical projection; manubrium flask-shaped, cross-like in section, almost as long as bell cavity, emerald green in colour; mouth cruciform with 4 prominent, recurved lips; without mesenteries; 8 gonads in adradial pads with smooth surface; 2 large elongated conical basal bulbs, each with a very long tapering opposed marginal tentacle, violet, their proximal part intensively purple; 12–24 small marginal warts, without tentaculae; without ocelli.

Developmental stages. Newly liberated medusa spherical, no apical projection present, scattered nematocysts on exumbrella; manubrium cylindrical, about 1/3 of height of bell cavity, reddish orange; two opposite tentacular marginal bulbs, same in colour as manubrium, each with a long tentacle, at place of other tentacles only small marginal warts.

Cnidome. Microbasic euryteles, desmonemes (hydroid); only microbasic euryteles (medusa).

Distribution. Atlantic, Indo-Pacific, Mediterranean ( Motz-Kossowska 1905; Neppi & Stiasny 1913; Russell 1953; Vannucci 1957; Kramp 1961; Patriti 1970; Goy et al. 1991; Medel & López-González 1996; Schuchert 1996, 2007; Gravili et al. 2008a; Puce et al. 2009; Touzri et al. 2010).

Records in Salento. Rare at: Porto Cesareo, S.ta Caterina, Otranto (Ionian and Adriatic Apulian coast) ( Denitto 1996; Miglietta et al. 2000; this study).

Remarks. The life cycle of A. dinema has been investigated by Rittenhouse (1910), Rees & Russell (1937), Schuchert (1996), and in this study.

References. Schneider (1898), Motz-Kossowska (1905), Rees & Russell (1937), Russell (1953), Trégouboff & Rose (1957), Picard (1958a), Kramp (1959), Rossi (1961), Balduzzi et al. (1980), Boero (1981a, b), Boero & Fresi (1986), Medel & López-González (1996), Schuchert (1996), Miglietta et al. (2000), Bouillon et al. (2004), Benović et al. (2005), Gravili (2006), Schuchert (2007, 2012), Gravili et al. (2008a), Puce et al. (2009), Touzri et al. (2010).

Figures

FIGURE 29. Amphinema dinema: A, portion of a hydroid colony with medusa bud; B, medusa (A, B same scale bar) (drawn by C. G. Di Camillo). Scale bar: A. B, 4.0 mm