Fig. 4 A–C
See Schuchert (2007) for a complete synonymy.
Material examined. HCUS-S 0 0 4 (Hydrozoa Collection, University of Salento—fauna of the Salento Peninsula).
Description (after Stechow 1919; Millard 1975; Schuchert 2001 a, 2007, 2012):
Hydroid. Hydrorhiza as reticulate stolons from which stems arise, covered with perisarc; colony erect, up to a maximum height of 25 mm; hydrocauli monosiphonic, unbranched or irregularly branched, increasing in diameter from base to distal end, covered with thick perisarc (wrinkled especially at base) variably continued or not on hydranth body as pseudohydrotheca; hydrocladia branching at acute angles from stem; hydranths fusiform, terminal on hydrocaulus or hydrocladia; hypostome conical; with one whorl of 10–16 filiform tentacles; pseudohydrotheca, when present, usually short, only covering basal part of the hydranth; gonophores borne on blastostyles arising on stem or on hydrorhiza as modified polyps without mouth or tentacles but with a long and extensile hypostome with cnidocysts; colonies dioecious. Colour: perisarc brown.
Swimming gonophores: as sporosacs, in a dense cluster below hypostome, ciliated with 2 basal tentacles; females containing 2 eggs.
Cnidome. Large microbasic euryteles, only on tip of blastostyles; smaller microbasic euryteles; desmonemes, only on tentacles on gastrozooids.
Habitat type and substrate. Occurring on mollusc shells (Murex, Cerithium vulgatum), usually in depths of 5–300 m (Motz-Kossowska 1905; Stechow 1919).
Seasonality. Spring-autumn in the Mediterranean Sea (Stechow 1919; Schuchert 2007).
Reproductive period. Summer and autumn (Schuchert 2007).
Distribution. North Atlantic from Arctic to the Mediterranean (Sars 1874; Hincks 1868; Allman 1872; Hartlaub 1894; Motz-Kossowska 1905; Jäderholm 1909; Robson 1914; Broch 1916; Schuchert 2001 a, 2007; Vervoort 1946, 1985; Leloup 1947; Picard 1958 a; Naumov 1969; Rees & Rowe 1969; Christiansen 1972; Medel & López-González 1996; Calder 2003; Bouillon et al. 2004); also recorded from South Africa (Millard 1975).
Records in Salento. Rare at Otranto (Ventura 2011).
Remarks. For a reliable identification of Dicoryne species, either released sporosacs or female sporosacs on the gonozooid must be examined (Schuchert 2001 a, 2007).
References. Motz-Kossowska (1905), Broch (1916) as Bougainvillia conferta; Stechow (1919), Millard (1975), Altuna (1994), Medel & López-González (1996), Schuchert (2001 a, 2007, 2012), Bouillon et al. (2004).