Nemertesia ramosa Lamarck 1816

Nemertesia ramosa (Lamarck, 1816)

Fig. 89 A–E

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

Material examined. HCUS-S 0 96 (Hydrozoa Collection, University of Salento—fauna of the Salento Peninsula).

Description (after Ramil & Vervoort 1992; Cornelius 1995; Medel & Vervoort 1995):

Hydroid. Hydrorhiza as strongly intertwined mat of many ramified tubes; colonies erect, well developed; hydrocauli large, polysiphonic, branched, up to about 200 mm high, one of the tubes of greater diameter, giving rise to hydrocladia in the monosiphonic and weakly polysiphonic parts and divided into internodes by transverse nodes, with hydrocladia-bearing apophyses at nodes, in opposite pairs in younger parts of the axis, in verticils of 3–10 in the older ones, verticils of succeeding pairs alternate, apophyses with a mamelon on the upper surface and several nematothecae (up to 7), coenosarc of main stem in several tubes, perisarc very thick, contrary to the thin perisarc of the hydrocladia; hydrocladia separated into thecate internodes by means of transverse nodes, each with one hydrotheca and 4 nematothecae, one median inferior, 2 lateral ones and one median superior one at the distal part of the segment; hydrothecae small, cup-shaped, entirely adnate, rim even, aperture at right angle with the axis; nematothecae all two-chambered, conical, basal chamber longer than apical one, chamber shorter, with a wide adcauline embayment. Male and female gonothecae similar, ovoid, obliquely truncated distally with a subterminal and oval aperture, narrower basally, with a short pedicel, male gonotheca with large circular, slightly oblique aperture, female gonotheca larger, aperture more or less oval, more oblique than in male gonotheca, both sexes insert on apophyses. Colours: coenosarc yellow-buff; hydrocladia colourless; male gonothecal contents white, female orange.

Cnidome. Microbasic mastigophores.

Habitat type. Muddy and sandy bottoms, it has been found from 5 to about 500 m depth (Gili 1986; Ramil & Vervoort 1992).

Substrate. Coralline shoals, hydroids, carapace of Decapoda of the genus Pisa, anthozoans or directly attached in mud or to rocks, shells of bivalves on non-living substrata, both biotic (remains of organism) and abiotic (pebbles).

Seasonality. August–September (Bianchi et al. 1993a) in the Tyrrhenian Sea; June, July, October–March (Bouillon et al. 2004); January (Galea 2007) in the western Mediterranean; September (Mastrototaro et al. 2010) in Salento waters.

Reproductive period. January (Roca 1986), February (Stechow 1919), July (Picard 1955; Peña Cantero & García Carrascosa 2002), December (Roca 1986) in the western Mediterranean; September (Mastrototaro et al. 2010) in Salento waters.

Distribution. Widely distributed in the eastern Atlantic and Mediterranean (Ramil & Vervoort 1992; Medel & Vervoort 1995; Ramil et al. 1998; Schuchert 2001a; Bouillon et al. 2004; Fanelli et al. 2013).

Records in Salento. Rare at S. Maria di Leuca (Mastrototaro et al. 2010). Other Apulian records: Northern coast (Marano et al. 1991).

Remarks. Juvenile Nemertesia ramosa resembles N. norvegica with which it may have been confounded quite often; indeed, their microscopical structure is also very similar (for more details see Schuchert 2001a).

References. Carus (1884), Lo Bianco (1909), Neppi (1921), Stechow (1919), Broch (1933), Leloup (1934), Picard (1958a), Rossi (1971), García Carrascosa (1981), Roca (1986), García-Carrascosa et al. (1987) as N. disticha; Ramil (1988), Marano et al. (1991), Morri et al. (1991), Ramil & Vervoort (1992), Álvarez Claudio (1993), Medel & Vervoort (1995), Medel & López-González (1996), Piraino et al. (1999), Ansín Agís et al. (2001), Peña Cantero & García Carrascosa (2002), Bouillon et al. (2004), Galea (2007), Mastrototaro et al. (2010).