Filellum serpens Hassall 1848

Filellum serpens (Hassall, 1848)

Fig. 80 A–C

See Schuchert (2001a) for a complete synonymy.

Material examined. HCUS-S 0 87 and HCUS-S 0 88 (Hydrozoa Collection, University of Salento—fauna of the Salento Peninsula).

Description (based on our own observations; Schuchert 2001a):

Hydroid. Hydrorhiza as irregularly branched stolons; colonies stolonal; hydranths with conical hypostome; with 8–12 amphicoronate tentacles; hydrothecae tubular, at irregular intervals, sessile, basal part (1/4–2/3) adnate to hydrorhiza, distal part curving upwards from the stolons, adnate portion smooth, rim even, usually everted, several hydrothecal renovations frequent. Colonies hermaphroditic. Gonothecae as fixed sporosacs, clustered into coppiniae, with simple curved accessory tubes, between gonothecae, irregularly shaped, not branching, either curving horizontally in middle and overarching gonothecae like dense canopy or nearly straight, giving coppinia a spiny appearance; embryos develop in acrocysts.

Cnidome. Microbasic mastigophores.

Habitat type. Coastal waters on hard bottom (depth range: 0.5– 50 m) (Boero & Fresi 1986; Schuchert 2001a; Peña Cantero & García Carrascosa 2002).

Substrate. Mostly on other hydroids, Posidonia, algae, bryozoans, sponges.

Seasonality. August (Stechow 1919); August–April (Boero & Fresi 1986); January–December (Llobet i Nidal 1987; Llobet et al. 1991; De Vito 2006; this study) in the Mediterranean Sea.

Reproductive period. February (Boero & Fresi 1986) in the Ligurian Sea; September (De Vito 2006; this study) in Salento waters.

Distribution. Cosmopolitan (Medel & López-González 1996; Schuchert 2001a; Peña Cantero & García Carrascosa 2002; Bouillon et al. 2004; Gravili et al. 2008a).

Records in Salento. Common at: Torre dell'Inserraglio, S.ta Caterina (Presicce 1991); Otranto (De Vito 2006; Gravili 2006; Gravili et al. 2008a; this study).

Remarks. For a recent discussion of the genus and its species see Marques et al. (2011).

References: Stechow (1919), Broch (1933), Picard (1951a, 1958a), Rossi (1961), Boero (1981a, b), Gili (1982, 1986), Boero & Fresi (1986), Llobet et al. (1986, 1991), Llobet i Nidal (1987), García-Carrascosa et al. (1987), Roca et al. (1991), Medel & López-González (1996), Peña Cantero et al. (1998), Schuchert (2001a), Peña Cantero & García Carrascosa (2002), Bouillon et al. (2004), De Vito (2006), Gravili (2006), Gravili et al. (2008a), Puce et al. (2009), Marques et al. (2011).