Halecium nanum Alder, 1859

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 : 92-93

Halecium nanum Alder, 1859

Fig. 64 A–C

See Cornelius (1995) for a complete synonymy.

Material examined. HCUS-S 0 71 (Hydrozoa Collection, University of Salento—fauna of the Salento Peninsula).

Description (based on our own observations; Calder 1991; Cornelius 1995):

Hydroid. Colonies erect; hydrocauli monosiphonic, up to 3 mm, unbranched or irregularly branched in several planes, sometimes dichotomously, internodes borne laterally at upper part of previous internode, narrowed, curved and with several basal annulations, distally smooth, without distinct nodes; primary hydrotheca at distal end of each internode, sessile, shallow, walls frequently thick and diverging, but not everted at the rim, secondary hydrothecae provided with hydrophores also basally annulated. Gonophores sac-shaped, borne on short pedicels arising on lateral apophysis to the hydrothecae, one side of gonotheca with 2 closely appressed tubes largely immersed in gonothecal wall and annulated, each topped by a hydrotheca provided with hydranth, opposite side of gonotheca convex.

Cnidome. Microbasic euryteles and mastigophores.

Habitat type. Shallow water species ( Boero & Fresi 1986; Calder 1991).

Substrate. Algae, Posidonia , barnacles.

Seasonality. April–December ( Boero & Fresi 1986); February (Puce et al. 2009; De Vito 2006; this study); April, August (De Vito 2006; this study) in the Mediterranean Sea.

Reproductive period. Unknown.

Distribution. Eastern and western Atlantic, Mediterranean, Pacific (Stechow 1925; Yamada 1959; Cornelius 1995; Medel & López-González 1996; Watson 1996; Medel et al. 1998; Medel & Vervoort 2000; Bouillon et al. 2004; Puce et al. 2009).

Records in Salento. Rare at: La Strea, Porto Cesareo ( Faucci & Boero 2000); Costa Merlata, Otranto ( Fraschetti et al. 2002); Grotta del Ciolo (Denitto et al. 2007; Moscatello & Belmonte 2007); Otranto (De Vito 2006; Gravili 2006; Gravili et al. 2008a; this study). Other Apulian records: Gargano ( Fraschetti et al. 2002).

Remarks. The colony somewhat resembles that of H. lankesteri (for details see Schuchert 2005b).

References. Schneider (1898), Motz-Kossowska (1911), Picard (1958a), Boero (1981a, b), Boero et al. (1985), Boero & Fresi (1986), Llobet et al. (1986), García-Rubies (1987), Medel & López-González (1996), Medel et al. (1998), Piraino et al. (1999), Faucci & Boero (2000), Medel & Vervoort (2000), Fraschetti et al. (2002), Bouillon et al. (2004), De Vito (2006), Gravili (2006), Denitto et al. (2007), Moscatello & Belmonte (2007), Gravili et al. (2008a), Puce et al. (2009).

Figures

FIGURE 64. Halecium nanum: A, part of colony; B, hydrotheca renovations and hydranth; C, female gonotheca (A, C redrawn and modified after Cornelius 1995 by C. G. Di Camillo; B drawn by F. Boero). Scale bars: A, B, 500 µm; C, 250 µm.