Plumularia setacea (Linnaeus, 1758)

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 : 127-128

Plumularia setacea (Linnaeus, 1758)

Fig. 90 A–D

See Medel & Vervoort (1995) and Schuchert (2001a) for a complete synonymy.

Material examined. HCUS-S 0 97 (Hydrozoa Collection, University of Salento—fauna of the Salento Peninsula).

Description (based on our own observations; Ramil & Vervoort 1992; Cornelius 1995; Medel & Vervoort 1995):

Hydroid. Hydrorhiza tubular, variably ramified in accordance to the substrate; colonies erect, pinnate; hydrocauli monosiphonic, unbranched, but occasionally branched, up to ca 60 mm, divided into internodes by transverse nodes, each segment bearing a basal and a distal nematotheca, the last one almost in the axil of a lateral apophysis; hydrocladia alternate, borne on stem apophyses, in the same plane, heteromerously segmented by transverse nodes into hydrothecate and non-hydrothecate internodes; hydrothecate internodes with one hydrotheca and 3 nematothecae, one inferior median one and 2 latero-superior ones, non-hydrothecate segments with one frontal nematotheca, usually with one perisarcal septum above and below it, septum also may occur basally on hydrothecate internodes; first hydrocladial internode athecate and shorter; hydrothecae cup-shaped, entirely adnate, rim even, aperture slightly tilted downwards; nematothecae all two-chambered, conical, basal chamber longer, apical one wider, with adcauline embayment. Gonothecae of both sexes on the same stem or not, typically in a continuous line towards the base of stem, female ones elongated, fusiform, smooth, narrower distally with a more or less developed tubular neck, with narrow and circular apical aperture, male ones narrower and smaller than females, less attenuate above, tapering to a minute orifice. Colours: stem pale to dark horn (dark brown in some old colonies).

Cnidome. Microbasic mastigophores.

Habitat type. Eurybathic species, in the Mediterranean Sea found from the tidal level to about 400 m depth ( Broch 1933; García Carrascosa 1981; Boero & Fresi 1986; Roca 1986; Ramil & Vervoort 1992).

Substrate. Recorded on other hydroids, sponges, barnacles, Posidonia , algae, mollusc shells, bryozoans, other organisms, and biogenic banks.

Seasonality. January–March ( Llobet i Nadal 1987; Llobet et al. 1991; Puce et al. 2009), April ( Llobet i Nadal 1987; Llobet et al. 1991), July ( Llobet i Nadal 1987; Llobet et al. 1991; Brahim et al. 2010), August ( Boero & Fresi 1986; Brahim et al. 2010), and November ( Boero & Fresi 1986) in the several localities of the Mediterranean Sea; all year in Salento waters (De Vito 2006; this study).

Reproductive period. February ( Ramil 1988), March ( Stechow 1923; Puce et al. 2009), May ( Stechow 1919; Rossi 1961), June ( Picard 1955; Morri & Bianchi 1999), August and September ( Picard 1952) in the several localities of the Mediterranean Sea; October–May (De Vito 2006; this study) in Salento waters.

Distribution. Cosmopolitan ( Millard 1975; Cornelius & Ryland 1990; Medel & Vervoort 1995; Ramil et al. 1998; Bouillon et al. 2004; Gravili et al. 2008a).

Records in Salento. Common at: La Strea, Porto Cesareo ( Presicce 1991; Denitto 1996; Faucci & Boero 2000); Montagna Spaccata, Torre S. Emiliano, Ponte del Ciolo ( Presicce 1991); Otranto ( Denitto 1996; Miglietta et al. 2000; Fraschetti et al. 2002; De Vito 2006; Gravili 2006; Andreano 2007; Gravili et al. 2008a; Stabili et al. 2008; Ventura 2011; Piraino et al. 2013; this study); Costa Merlata ( Fraschetti et al. 2002; Andreano 2007); Il Chiapparo (C. Gravili unpublished observations).

Remarks. For more details about the variability of this species see Ramil & Vervoort (1992).

References. Broch (1912, 1933), Stechow (1919, 1923), Billard (1926), Leloup (1934), Rossi (1950, 1961, 1971), Picard (1952, 1958a), Riedl (1959, 1970, 1991), Schmidt (1973), Hughes (1975), Chas & Rodriguez (1977), García-Corrales et al. (1978), Morri (1980b), García Carrascosa (1981), Isasi (1985), Boero & Fresi (1986), Gili (1986), Roca (1986), Llobet i Nidal (1987), Ramil (1988), Llobet et al. (1991), Ramil & Vervoort (1992), Alvarez Claudio (1993), Altuna (1994), Medel & Vervoort (1995), Medel & López-González (1996), Morri & Bianchi (1999), Morri et al. (1999), Piraino et al. (1999), Faucci & Boero (2000), Miglietta et al. (2000), Ansín Agís et al. (2001), Fraschetti et al. (2002), Peña Cantero & García Carrascosa (2002), Bouillon et al. (2004), De Vito (2006), Gravili (2006), Gravili et al. (2008a), Morri et al. (2009), Puce et al. (2009), Brahim et al. (2010), Bianchi et al. (2011), Ventura (2011), Piraino et al. (2013).

Figures

FIGURE 90. Plumularia setacea: A, general view of a colony; B, parts of stem showing origins of hydrocladia and gonothecae; C, detail of hydrocladium; D, gonotheca (A, B drawn by L. Basso; C, D drawn by C. G. Di Camillo). Scale bars: B, D, 500 µm; C, 250 µm.