Sertularella polyzonias Linnaeus 1758

Sertularella polyzonias (Linnaeus, 1758)

Fig. 96 A–D

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

Material examined. HCUS-S 103 (Hydrozoa Collection, University of Salento—fauna of the Salento Peninsula).

Description (based on our own observations; Ramil & Vervoort 1992; Ramil et al. 1992; Medel & Vervoort 1998; Schuchert 2001a):

Hydroid. Hydrorhiza as tubular, ramified stolons of varied thickness; colonies erect, sometimes flexuous; hydrocaulus up to ca 70 mm, monosiphonic or polysiphonic basally, with mostly smooth perisarc, regularly segmented, nodes transverse to oblique, thecate internodes separated by oblique nodes alternatively directed to the left and the right; hydrocladia arranged irregularly, with some second and third order branching, similar in structure to hydrocaulus; hydrothecae lateral, alternate, in the same plane, tubular, swollen basally and narrowed distally, walls usually thin, aprox. 1/2 adcauline wall adnate, margin slightly tilted outwards or perpendicular to the axis of the hydrotheca, internal projections can be incidentally present. Gonothecae elongated, horizontally ridged, narrowed distally, with 2–4 (usually 4) distal cusps, female ones with acrocyst when brooding.

Cnidome. Microbasic mastigophores.

Habitat type. Found from 4 to 400 m depth (Broch 1933; Marinopoulos 1981; Boero & Fresi 1986).

Substrate. Algae, Zostera spp., Posidonia oceanica, other hydroids, coralligenous, polychaete tubes, and dead gorgonians.

Seasonality. November, December (Boero & Fresi 1986), January–May, November, December (Puce et al. 2009) in the Ligurian Sea; February, March, May (this study); almost always present (for a review see Bouillon et al. 2004).

Reproductive period. January (Puce et al. 2009), February and April (Broch 1933; Puce et al. 2009; this study), May (Medel et al. 1991), July and August (Peña Cantero & García Carrascosa 2002), August and September (Picard 1951b), November (Broch 1933; Boero & Fresi 1986; Puce et al. 2009), and December (Roca 1986; Puce et al. 2009) in several localities of the Mediterranean Sea.

Distribution. Cosmopolitan (Ramil et al. 1992; Cornelius 1995; Medel & López-González 1996; Medel & Vervoort 1998; Schuchert 2001a; Peña Cantero & García Carrascosa 2002; Bouillon et al. 2004; Gravili et al. 2008a).

Records in Salento. Rare in the following localities: La Strea, Torre dell'Inserraglio, Torre S. Emiliano, La Rotonda (Presicce 1991); Otranto (De Vito 2002; this study).

Remarks. The validity of this species has been questioned by Cornelius (1979), but Schuchert (2001a) considered S. polyzonias a valid species; for a discussion and distinction from S. gayi see Schuchert (2001a).

References. Babic (1910, 1921), Broch (1912, 1933), Stechow (1919), Neppi (1921), Leloup (1934), Rossi (1950), Picard (1951a, 1958a), Rossi (1971), Boero (1981a, b), García Carrascosa (1981), Boero & Fresi (1986), Llobet i Nadal (1987), Llobet et al. (1991), Marano et al. (1991), Medel et al. (1991), Ramil & Vervoort (1992), Ramil et al. (1992), Medel & López-González (1996), Medel & Vervoort (1998), Piraino et al. (1999), Schuchert (2001a), De Vito (2002), Peña Cantero & García Carrascosa (2002), Bouillon et al. (2004), Gravili (2006), Galea (2007), Gravili et al. (2008a), Morri et al. (2009), Puce et al. (2009).