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 ( 2001 a) 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. 2008 a).

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. 2008 a; 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 ( 1980 b), 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. ( 2008 a), 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.