Dynamena disticha (Bosc, 1802)

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 : 128-129

Dynamena disticha (Bosc, 1802)

Fig. 91 A–D

See Medel & Vervoort (1998) for a complete synonymy.

Material examined. HCUS-S 0 98 (Hydrozoa Collection, University of Salento—fauna of the Salento Peninsula).

Description (based on our own observations; Medel et al. 1991; Peña Cantero & García Carrascosa 2002):

Hydroid. Hydrorhiza as tubular, branching stolons; colonies erect; hydrocauli monosiphonic, up to ca 30 mm, unbranched, axis base athecate, ending with an oblique node, remaining internodes thecate with distinct or indistinct transverse nodes, each with a pair of frontally placed, opposite hydrothecae; hydrotheca tubular, basal half parallel with axis, distal half curving outwards forming 45º with the axis, 1/2—2/3 of adcauline walls of each pair of hydrothecae touching frontally. Gonothecae almost spherical, with rounded transverse ridges and truncated distally, aperture circular on a short collar, operculum with one circular valve.

Cnidome. Microbasic mastigophores.

Habitat type. In the Mediterranean Dynamena disticha has been found from the tidal level to 60 m depth (García Carrascosa 1981; Boero & Fresi 1986; Roca 1986).

Substrate. Algae, leaves and rhizomes of Posidonia oceanica , rock, hydroids, polychaete tubes, bryozoans, other organisms such as sponges, cirripedes, molluscs, and holothurians.

Seasonality. January–December ( Boero & Fresi 1986; De Vito 2006; this study); January–February (Puce et al. 2009); April ( Stechow 1919); July ( Peña Cantero & García Carrascosa 2002); August ( Peña Cantero & García Carrascosa 2002; Galea 2007); May–December (Puce et al. 2009) in several localities of the Mediterranean Sea.

Reproductive period. February (Gili 1986), June (Gili 1986; Roca 1986), July ( Boero & Fresi 1986; Roca 1986), August and September ( Picard 1952; Boero & Fresi 1986; Puce et al. 2009), October and November ( Boero & Fresi 1986), July and August ( Peña Cantero & García Carrascosa 2002) in the western Mediterranean; June–September in Salento waters (De Vito 2006; this study).

Distribution. Circumglobal, in subtropical and tropical seas ( Marinopoulos 1979; Medel & López-González 1996; Medel & Vervoort 1998; Peña Cantero & García Carrascosa 2002; Bouillon et al. 2004; Soto Ãngel & Peña Cantero 2013).

Records in Salento. Common at: La Strea, Porto Cesareo ( Faucci & Boero 2000; Kubota & Gravili 2011); Il Chiapparo, Otranto (De Vito 2006; Gravili 2006; Gravili et al. 2008a; this study). Other Apulian records: coast of Bari ( Marano & Vaccarella 1970).

Remarks For a complete discussion about the taxonomy of this variable species see Calder (1991).

References. Neppi (1917) as Disertasia cavolini ; Stechow (1919, 1923) as Dynamena densa ; Leloup (1934); Picard (1952), Riedl (1959) as Dynamena cavolinii ; Rossi (1961), Marano & Vaccarella (1970), Morri (1979c, 1980b), Boero (1981a, b, 1985), García Carrascosa (1981), Boero & Fresi (1986), Gili (1986), Roca (1986), Medel et al. (1991), El-Beshbeeshy (1995), Medel & López-González (1996), Migotto (1996), Medel & Vervoort (1998), Piraino et al. (1999), Faucci & Boero (2000), Peña Cantero & García Carrascosa (2002), Bouillon et al. (2004), De Vito (2006), Gravili (2006), Galea (2007), Gravili et al. (2008a), Puce et al. (2009); Brahim et al. (2010)? as D. cavolinii ; Kubota & Gravili (2011).

Figures

FIGURE 91. Dynamena disticha: A, hydrothecae; B, variability of the hydrothecae; C, gonotheca (A, B, C same scale bar); D, nematocysts (drawn by F. Boero). Scale bars: A, B, C, 0.5 mm; D, 20 µm.