Eudendrium armatum Tichomiroff, 1887

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 : 24-25

Eudendrium armatum Tichomiroff, 1887

Fig. 14 A–E

See Schuchert (2008b) for a complete synonymy.

Material examined. HCUS-S 0 16 and HCUS-S 0 17 (Hydrozoa Collection, University of Salento—fauna of the Salento Peninsula).

Description (based on our own observations; Marinopoulos, 1992; Marques et al., 2000a, b; Schuchert, 2008b):

Hydroid. Hydrorhiza rhizocaulomic; colonies erect, up to 65 mm high; hydrocaulus polysiphonic and branched, perisarc with several groups of annuli elsewhere; hydrocladia more or less alternate but not in the same plane, ringed basally and with several annulations at the base of renovated portions; hydranths typical of the genus; hypostome flared; with approximately 24 tentacles, proximal portion of tentacles devoid of nematocysts, the density of which gradually increases towards distal end where they form untidy bands; nematophores irregularly distributed throughout the colony, naked, large and thin, each borne on a pedicel. Gonophores as fixed sporosacs; females with unbranched spadix, males with 2–3 chambers. Colours: perisarc of the stem brown to yellowish (in younger parts).

Cnidome. Heterotrichous microbasic euryteles (5x 3 to 6 x 4 mm) on tentacles and ectoderm, also the same type (8x 4 to 9 x4.5 µm) on the hypostome, the hydranth and on the hydrocaulus; butt thin.

Habitat type. Very abundant in small caves and crevices, from 1 to 40 m, generally on rocks ( Picard 1951a; Riedl 1966; Marinopoulos 1979, 1992; Boero & Fresi 1986; Gili 1986; Balduzzi et al. 1995; Morri & Bianchi 1999; Morri et al. 1999; Piraino et al. 1999; Marques et al. 2000a, b; Puce et al. 2009).

Substrate. Concretions, massive sponges ( Ircinia , Petrosia ), algae ( Corallina , Peyssonnelia , Halimeda tuna ).

Seasonality. In the Ligurian Sea ( Boero & Fresi 1986; Puce et al. 2009) in January, July March, December; in Salento waters (De Vito 2006; this study) in February, September–October.

Reproductive period. February–March, and from July to October ( Boero & Fresi 1986; Marques et al. 2000a; De Vito 2006; this study).

Distribution. Mediterranean endemic ( Marques et al. 2000a, b; Bouillon et al. 2004; Gravili et al. 2008a; Schuchert 2008b; Soto Ãngel & Peña Cantero 2013).

Records in Salento. Common at Otranto, on overhangs and cave entrances (De Vito 2006; Gravili 2006; Gravili et al. 2008a; this study).

Remarks. Colony form very similar to that of E. rameum (Pallas) whose Mediterranean records might often be referred to E. armatum .

References. Picard (1951a, 1958a), Gili (1986), Boero & Fresi (1986), Marinopoulos (1979, 1990, 1992), Medel & López-González (1996), Balduzzi et al. (1995), Morri & Bianchi (1999), Morri et al. (1999), Piraino et al. (1999), Marques et al. (2000a, b), Bouillon et al. (2004), Puce et al. (2005a, 2009), De Vito (2006), Gravili (2006), Gravili et al. (2008a), Schuchert (2008b).

Figures

FIGURE 14. Eudendrium armatum: A, general view of a colony; B, portion of a colony with nematophore; C, hydranth; D, mature male blastostyle; E, nematocysts (A, B, C, D drawn by C. G. Di Camillo; E drawn by F. Boero). Scale bars: A, 1.0 cm; B, 0.5 mm; C, D, 0.2 mm; E, 10 µm.