Stylactaria fucicola (M. Sars, 1857)

Fig. 10 A–D

See Schuchert (2008a, 2013) for a complete synonymy.

Material examined. HCUS-S 0 11 and HCUS-S 0 12 (Hydrozoa Collection, University of Salento—fauna of the Salento Peninsula).

Description (based on our own observations; Stechow 1919, Schuchert 2008a both as Hydractinia fucicola):

Hydroid. Hydrorhiza encrusting, covered by naked coenosarc, with or without numerous spines; colonies stolonal, polymorphic with gastrozooids, gonozooids, and sometimes tentaculozooids; gastrozooids fusiform to cylindrical, up to 3 mm long, without perisarc collar at base; hypostome cylindrical; 6–12 tentacles; gonozooids usually smaller and more slender than gastrozooids, 4–8 tentacles and trumpet-shaped hypostome; colonies dioecious. Gonophores as fixed sporosacs, males spherical, females slightly flattened on both extremes, with 6– 12 eggs; both covered by numerous nematocysts, without radial canals or tentacle rudiments, spadix present. Colours: spine perisarc brown, hydranths orange or pink.

Cnidome. Microbasic euryteles of two size classes, desmonemes; both gastrozooids and gonozooids with a characteristic ring of large microbasic eurytele cnidocysts surrounding the hypostome above the tentacle whorl.

Habitat type. In the Mediterranean, S. fucicola occurs only in shallow waters (0–30 m) (Boero & Fresi, 1986; Schuchert 2008a).

Substrate. Algae, hydroids, barnacles, Posidonia leaves, sponges.

Seasonality. In the Ligurian Sea from January to August, November–December (Boero & Fresi 1986; Puce et al. 2009); in Salento waters from November to May (De Vito 2006; this study).

Reproductive period. In the Ligurian Sea (Boero & Fresi 1986; Puce et al. 2009), reproductive colonies occur in April, August; from February to April (De Vito 2006; this study) in Salento waters.

Distribution. Northeastern Atlantic, Mediterranean (Castric-Fey 1970; Medel & López-González 1996; Bouillon et al. 2004; Gravili et al. 2008a; Schuchert 2008a; Puce et al. 2009).

Records in Salento. Common at Porto Cesareo (Faucci & Boero 2000); Costa Merlata (Fraschetti et al. 2002; Gravili 2006; Gravili et al. 2008a); Otranto (De Vito 2006; Gravili 2006; Gravili et al. 2008a; Ventura, 2011; Piraino et al. 2013; this study); Torre Lapillo (Andreano 2007).

Remarks. The presence of spines depends on the substrate (Schuchert, 2008a). Miglietta & Cunningham (2012) referred this nominal species to Stylactaria. Boero et al. (1998) interpreted the evolutionary trend of medusa reduction of the hydractiniids as repeated episodes of heterochrony.

References. Motz-Kossowska (1905) as Hydractinia fucicola, Mayer (1910) as Stylactis fucicola, Stechow (1919) as H. fucicola, Picard (1952, 1958a) as Podocoryna fucicola, Castric-Fey (1970) as H. fucicola, Marinopoulos (1979) as P. fucicola, Gili et al. (1984) as Podocoryne fucicola, Boero & Fresi (1986) as Stylactis fucicola, Barangé & Gili (1987) as P. fucicola; Medel & López-González (1996), Bouillon et al. (1997), Faucci & Boero (2000), Fraschetti et al. (2002), Bouillon et al. (2004), De Vito (2006), Gravili (2006), Gravili et al. (2008a), Schuchert (2008a), Puce et al. (2009), Ventura (2011), Piraino et al. (2013) all as H. fucicola.