Ectopleura dumortierii (Van Beneden, 1844)

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 : 60-62

Ectopleura dumortierii (Van Beneden, 1844)

Fig. 41 A, B

See Schuchert (2010) for a complete synonymy.

Material examined. HCUS-S 0 46 (Hydrozoa Collection, University of Salento—fauna of the Salento Peninsula)—polyp stage.

Description (based on our own observations; Brinckmann-Voss 1970: Petersen 1990; Schuchert 2010, 2012): Hydroid. Solitary polyps; hydrocaulus up to 100 mm high, unbranched or slightly branched, ending in a terminal hydranth and increasing in width from base to distal end, hydrocaulus endoderm with up to 4 longitudinal ridges, covered by irregularly annulated perisarc until proximal end of hydranth; hydranth flask-shaped, neck region with gland cells forming an indistinct collar; hypostome rounded; with 14–25 rather short, rounded, oral filiform tentacles in one whorl, bases of tentacles not adnate to hypostome; one whorl of up to 30 long, aboral, semifiliform tentacles; medusa buds carried on 8–12 blastostyles, blastostyles initially short and Y-shaped, later longer and with several short sidebranches, buds of all developmental stages in dense clusters at ends of sidebranches and on main trunk of blastostyle; 8 longitudinal nematocyst tracks visible on advanced buds, arising in pairs from 4 equally developed marginal bulbs. Colours: perisarc may be horn-coloured or yellowish, hydranth body pink, blastostyles conspicuously red.

Habitat type. Shallow littoral (depth range: 0–20, also until to 65 m) (Schuchert 2010).

Substrate. Several substrates such as stones, other hydroids, shells, and bryozoans.

Seasonality. All year (for a review see Bouillon et al. 2004); in Salento waters in April, July (De Vito 2006; this study).

Reproductive period. In the Tyrrhenian Sea ( Brinckmann-Voss 1970, 1987), Ectopleura dumortierii occurs in winter months; from January to December in Salento waters (De Vito 2006; this study).

Medusa. Adult. Umbrella nearly spherical, 2–3 mm high, mesoglea very thick, especially in apical region, apical canal sometimes present; exumbrella with 4 pairs of cnidocyst tracks; manubrium spherical at base, tapering towards mouth, very large, extensile; mouth simple, tube-like, with band of fine spots around centre of stomach, circle of pigment around base of stomach near junction of radial canals, mouth rim with cnidocysts; gonads completely surrounding manubrium, leaving mouth area free; females produce only one or more usually 2 large, opposite eggs at one time, development through a pro-actinula and actinula stage; velum fairly broad; 4 perradial bulbs, each marginal bulb with one tentacle with prominent round cnidocyst clusters on abaxial surface. Colours: tentacle bulbs brownish or yellow, mouth orange or crimson, with band of fine red spots around centre of stomach, and brownish or yellow circle of pigment around base of stomach near junction of radial canals.

Developmental stages. Newly released medusa similar to mature one, only smaller, fine apical canal present or not, no gonads present, with 4 short tentacles with small terminal knobs and, sometimes, also one indistinct abaxial nematocyst cluster.

Cnidome. Stenoteles, desmonemes, spherical heterotrichous anisorhizas, microbasic mastigophores.

Distribution. Atlantic, Indo-Pacific, Mediterranean ( Stechow 1923; Russell 1953, 1957; Teissier 1965; Brinckmann-Voss 1970; Petersen 1990; Goy et al. 1991; Benović & Lučić 1996; Medel & López-González 1996; Bouillon et al. 2004; Gravili et al. 2008a; Schuchert 2010).

Records in Salento. Rare at Otranto (Apulia) (De Vito 2006; Gravili 2006; Gravili et al. 2008a; this study), S.ta Caterina, Taranto (S. Piraino unpublished observations).

Remarks. Petersen (1990) reviewed all Ectopleura species known from the polyp stage and also described several new species. Only the hydroid stage and the new born medusa were seen in the present study.

References. Stechow (1923), Russell (1953), Trégouboff & Rose (1957), Picard (1958a), Kramp (1959, 1961), Brinckmann-Voss (1970), Goy (1973), Schmidt & Benović (1979), Gili (1986), Benović & Bender (1987), Goy et al. (1988, 1990, 1991), Petersen (1990), Medel & López-González (1996), Migotto (1996), Bouillon et al. (2004), Touzri et al. (2004), De Vito (2006), Gravili (2006), Gravili et al. (2008a), Schuchert (2010, 2012).

Figures

FIGURE 41. Ectopleura dumortierii: A, hydranth; B, mature medusa (A, B same scale bar) (drawn by C. G. Di Camillo). Scale bars: A, B, 2.0 mm.