Clytia paulensis (Vanhöffen, 1910), Vanhoffen, 1910

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 : 148-149

Clytia paulensis (Vanhöffen, 1910)

Fig. 105 A–E

See Peña Cantero & García Carrascosa (2002) for a complete synonymy.

Material examined. HCUS-S 112p and HCUS-S 112m (Hydrozoa Collection, University of Salento—fauna of the Salento Peninsula)—polyp and medusa stages.

Description (based on our own observations; Stechow 1923; Ramil & Vervoort 1992; Cornelius 1995):

Hydroid. Hydrorhiza thin, as creeping stolon system; colony stolonal; pedicels arising at irregular intervals, erect and delicate, ringed basally and below hydrothecae (sometimes also centrally), usually unbranched, each supporting one hydrotheca; hydranth provided with 16–22 tentacles; hydrotheca cylindrical, deep, with a thin diaphragm at base, rim with 7–11 cusps usually bicuspidate and rounded. Gonothecae cylindrical, tapering gradually below and slightly above, smooth, borne on stolon on short and ringed pedicels.

Habitat type. Littoral and shelf species found from the tidal level to 250 m depth ( Stechow 1923; Marinopoulos 1981; Boero & Fresi 1986).

Substrate. Several other hydroid species, some bryozoans, shells of various invertebrates, stones, algae, rhizomes and leaves of Posidonia oceanica .

Seasonality. September–April ( Boero and Fresi, 1986), and February–June, August–December (De Vito 2006; Puce et al. 2009; this study) in several localities of the Mediterranean.

Reproductive period April (Gili 1986; C. Gravili unpublished observations), May ( Stechow 1923; C. Gravili unpublished observations), and July, August ( Peña Cantero & García Carrascosa 2002; C. Gravili unpublished observations) in the Mediterranean Sea.

Medusa. Adult. Fourteen-day-old medusa with umbrella flat, diameter about 4 mm, mesoglea fairly thin; manubrium quadrate, with small base, as long as the subumbrellar cavity; gonads oval on each radial canal, near manubrium; 24 marginal bulbs and tentacles; 1–2 statocysts between two adjacent bulbs. Colours: manubrium, gonads and marginal bulbs transparent.

Developmental stages. Newly released medusa with umbrella almost spherical, diameter about 1 mm, mesoglea thin; manubrium quadrate, ½ of length of subumbrellar cavity; mouth with 4 simple lips; 4 radial canals; 8 marginal bulbs (four reduced); 4 tentacles; 8 statocysts (C. Gravili unpublished observations). Nine-day-old medusa with umbrella hemispherical (diameter about 2 mm); mesoglea thin; manubrium quadrate, ½ of length of subumbrellar cavity; mouth with 4 simple lips; 4 radial canals; 4 small gonads on each radial canal near manubrium; 16 bulbs (8 tentaculated); 1–2 statocysts between two adjacent bulbs.

Cnidome. Microbasic mastigophores.

Distribution. Cosmopolitan ( Millard 1975; Ramil & Vervoort 1992; Cornelius 1995; Medel & López- González 1996; Bouillon et al. 2004; Gravili et al. 2008a; Soto Ãngel & Peña Cantero 2013).

Records in Salento. Rare at: Grotta del Ciolo (Denitto et al. 2007; Moscatello & Belmonte 2007); Otranto (De Vito 2006; Gravili 2006; Gravili et al. 2008a; Ventura 2011; Piraino et al. 2013; this study); Il Chiapparo (C. Gravili unpublished observations).

Remarks. The whole life cycle is described for the first time in the present study.

References. Stechow (1919, 1923), Leloup (1934), Picard (1951a, 1955, 1958 a), Riedl (1959), Fey (1970), Marinopoulos (1979), Boero (1981a, b, 1985), García Carrascosa (1981), Boero et al. (1985), Isasi (1985), Boero & Fresi (1986), Gili (1986), Ramil (1988), Ramil & Vervoort (1992), Altuna (1994), Medel & López-González (1996), Piraino et al. (1999), Medel & Vervoort (2000), Peña Cantero & García Carrascosa (2002), Bouillon et al. (2004), De Vito (2006), Gravili (2006), Denitto et al. (2007), Moscatello & Belmonte (2007), Gravili et al. (2008a), Puce et al. (2009), Ventura (2011), Piraino et al. (2013).

Figures

FIGURE 105. Clytia paulensis: A, detail of a part of colony; B, detail of hydrotheca; C, gonotheca; D, newly liberated medusa; E, adult medusa (A, B drawn by C. G. Di Camillo; C, D, E drawn by A. Gennari). Scale bars: A, B, 250 µm; C, 500 µm; D, 1.0 mm; E, 2.0 mm.