Eudendrium simplex Pieper, 1884

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 : 36

Eudendrium simplex Pieper, 1884

Fig. 23 A–D

See Schuchert (2008b) for a complete synonymy.

Material examined. HCUS-S 0 28 (Hydrozoa Collection, University of Salento—fauna of the Salento Peninsula).

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

Hydroid. Hydrorhiza simple as creeping; colonies erect, small, up to 12 mm high; ramified stolons; hydrocaulus monosiphonic, unbranched or sparsely branched, perisarc annulated on origins of hydrocladia and at other irregular intervals; hydranths on annulated or corrugated pedicel; 16–27 filiform tentacles in one whorl. Gonophores as fixed sporosacs, on hydranths which conserve the tentacles, “females” (hermaphroditic) 2–5 per blastostyle, with curved and unbranched spadix, containing one egg and one or more masses of spermatogenic cells at summit between spadix and superficial ectoderm; males 1–4 per blastostyle, unreduced, 1–2 chambered, with no terminal nematocyst button.

Cnidome. Holotrichous macrobasic euryteles (17x 7.5 to 23.5x10.5 µm) arranged in two whorls, one at the hypostome and the other one at the basal half of the hydranth; shaft long (8–10 times length of capsule) spirally coiled around the big axis, swollen distally to about double the width when discharged, armed with spirally arranged barbs; small heterotrichous microbasic euryteles (6.6x2.5 to 7.2 x 3 mm) on tentacles and ectoderm.

Habitat type. Occurs in shallow waters, to 15 m, mostly on Posidonia oceanica ( Gili & García-Rubies 1985; Boero & Fresi 1986; Schuchert 2008b).

Substrate. Posidonia oceanica , Halimeda tuna , Cystoseira spp., other hydroids, barnacles, sponges.

Seasonality. Always present in the Mediterranean Sea ( Boero & Fresi 1986; De Vito 2006; this study).

Reproductive period. In the western Mediterranean Sea, fertile colonies occur in summer ( Boero & Fresi 1986), April–November ( Gili & García-Rubies 1985; Schuchert 2008b).

Distribution. Mediterranean (see Marques et al. 2000a; Bouillon et al. 2004; Gravili et al. 2008a; Schuchert 2008b).

Records in Salento. Frequent but never abundant in the following localities: La Rotonda ( Presicce 1991); Porto Cesareo ( Faucci & Boero 2000); Otranto (De Vito 2006; Gravili 2006; Gravili et al. 2008a; Piraino et al., 2013; this study).

Remarks. The records from South Africa are uncertain ( Millard & Bouillon 1974; Millard 1975 as E. motzkossowskae ). If present, the hermaphroditic sporosacs allow a certain identification of this species ( Schuchert 2008b).

References. Motz-Kossowska (1905) as E. simplex ; Picard (1958a), Millard & Bouillon (1974), Millard (1975), Boero (1981a, b), Boero et al. (1985), Boero & Fresi (1986), Gili (1986), Llobet et al. (1986, 1991), García- Rubies (1987), Llobet i Nidal (1987), Marinopoulos (1990, 1992), Medel & López-González (1996), Piraino et al. (1999), Faucci & Boero (2000) all as E. motzkossowskae ; Marques et al. (2000a), Peña Cantero & García Carrascosa (2002), Bouillon et al. (2004), De Vito (2006), Gravili (2006), Gravili et al. (2008a), Schuchert (2008b), Morri et al. (2009), Piraino et al. (2013).

Figures

FIGURE 23. Eudendrium simplex: A, stem with two hydranths; B, blastostyle with male sporosacs; C, blastostyle (gonozooid) with developing female sporosacs and two encaupsuled embryos attached to pedicel (B, C same scale bar); D, undischarged nematocysts: microbasic and macrobasic euryteles (drawn by C. G. Di Camillo). Scale bars: A, 0.5 mm; B, C, 0.1 mm; D, 10 µm.