Hebella scandens (Bale, 1888)

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 : 106-107

Hebella scandens (Bale, 1888)

Fig. 75 A–C

See Boero et al. (1997a) for a complete synonymy.

Material examined. HCUS-S 0 82 (Hydrozoa Collection, University of Salento—fauna of the Salento Peninsula)—polyp stage.

Description (based on our own observations; Boero et al. 1997a):

Hydroid. Colonies stolonal; hydranths with 12–16 tentacles; hydrothecae asymmetrical, with perisarcal diaphragm, with smooth to slightly corrugated walls, flared margin, mostly oblique but bent 90° when growing over host hydrothecae, pedicels short, smooth or annulated. Gonothecae asymmetrical, with undulated walls, truncated distally, tapering toward base, operculum with 4 opercular flaps, bigger than hydrothecae, on short pedicels, containing up to 4 medusa buds.

Habitat type and substrate. Littoral and shelf species found from the tidal level to 120 m depth (García Carrascosa 1981; Templado et al. 1986).

Substrate. Algae, epizootic on other hydroids, especially Sertulariidae , sponges, bryozoans, other organisms.

Seasonality. May, September ( Llobet i Nadal 1987) in the Western Mediterranean; January, February, April–July, November–December (for a review see Bouillon et al. 2004); just March (De Vito 2006; this study) in Salento waters.

Reproductive period. No references of fertile material from the Mediterranean.

Medusa. Newly released medusa. Bell deep-campanulate, mesoglea thicker at apex, exumbrella evenly covered by nematocysts; manubrium short; mouth with 4 small lips; 4 radial canals; 2 big tentacular bulbs and 6 smaller atentaculate bulbs, 2 perradial and 4 interradial ones; with an adaxial ocellus on each marginal bulb.

Cnidome. Microbasic mastigophores.

Distribution. Atlantic, Indo-Pacific, Mediterranean ( Medel & López-González 1996; Boero et al. 1997a; Bouillon et al. 2004; Gravili et al. 2008a).

Records in Salento. Rare at Otranto (De Vito 2006; Gravili 2006; Gravili et al. 2008a; this study).

Remarks. The hydrothecae can be almost symmetrical, or sharply asymmetrical, according to their position on the sertulariid hosts (for more details see Boero et al. 1997a). Gonothecae and medusae not seen in the present study.

References. Picard (1951a, 1958a), Millard (1957), Vervoort (1959), Rossi (1961, 1971), Millard & Bouillon (1973), Schmidt (1973), Sarà et al. (1978), Marinopoulos (1979, 1983), García Carrascosa (1981), Isasi (1985), Gili (1986), Roca (1986), Llobet i Nadal (1987), Calder (1991), Llobet et al. (1991), Vervoort (1993), Altuna (1994), Medel & López-González (1996) as Hebellopsis ; Migotto (1996), Altuna (1996), Boero et al. (1997a), Peña Cantero & García Carrascosa (2002), Bouillon et al. (2004), De Vito (2006), Gravili (2006), Gravili et al. (2008a).

Figures

FIGURE 75. Hebella scandens: A, straight hydrotheca and twisted one; B, portion of fertile colony growing on a sertulariid; C, juvenile medusa (modified after Boero et al. 1997 a). Scale bars: A, B, 0.5 mm; C, 1.0 mm.