The non-Siphonophoran Hydrozoa (Cnidaria) of Salento, Italy with notes on their life-cycles: an illustrated guide Author Gravili, Cinzia Author Vito, Doris De Author Camillo, Cristina Gioia Di Author Martell, Luis Author Piraino, Stefano Author Boero, Ferdinando text Zootaxa 2015 3908 1 1 187 journal article 42365 10.11646/zootaxa.3908.1.1 6f1d1977-6b97-4789-828c-76ed250cf1ae 1175-5326 242729 D6AD2B49-170B-4D9C-84AA-DBE0FEEAD8BE Porpita porpita (Linnaeus, 1758) Fig. 44 A–C See Schuchert (1996) for a complete synonymy. Material examined. HCUS-S 0 49 (Hydrozoa Collection, University of Salento—fauna of the Salento Peninsula)—medusa stage. Description (based on our own observations; Vanhoeffen 1906; Brinckmann-Voss 1970 ; Bouillon 1984a ; Calder 1988 ; Pagès et al. 1992 ; Schuchert 1996 ): Hydroid. Floating polymorphic colony, up to 30 mm diameter but mostly smaller, with disk-shaped mantle and internal float: margin soft and flexible, central region firm, slightly convex and with a central pore and numerous stigmata, mantle with radiating endoderm canals, internal chitinous float consisting of a series of concentric chambers, with a disk-shaped reservoir of cnidocysts between float and central gastrozooid, under surface with one large central gastrozooid, a median circle of gastro-gonozooids, and a peripheral circle of dactylozooids; gastrozooid central, short and broad, with a terminal mouth, without tentacles or prominent cnidocyst clusters; dactylozooids with a distal whorl of 4 capitate tentacles and a varying number of short, small capitate tentacles in 3 vertical rows on hydranth body; gastro-gonozooids clavate, lacking tentacles but with prominent cnidocyst clusters scattered over body, medusae buds developing near base in clusters. Colours: colony dark blue coloured. FIGURE 44. Porpita porpita : A , colony (seen from above); B , mature colony (lateral view); C , medusa ( A and B same scale bar) (A, C redrawn and modified after Schuchert 1996, B after Pagès et al . 1992 by A. Gennari). Scale bars: A, B, 10 mm; C, 2.0 mm. Habitat type . Colony floating on water surface ( Vanhöffen 1906 ; Calder 1988 ). Seasonality. In the Mediterranean Sea, Porpita porpita occurs in May, June, September–October ( Lo Bianco 1909 ; Tregouboff & Rose 1957 ); July–August (F. Boero unpublished observations). Reproductive period. Colonies usually bear small medusa buds throughout the period of presence on the water surface. Medusa. Adult. Umbrella rather conical, up to 2 mm diameter and 2.5 mm high; exumbrella with 8 perradial tracks of nematocysts, only one capsule wide; manubrium conical with octagonal base, length one-third of subumbrellar cavity; mouth circular; 8 radial canals with zooxanthellae, circular canal present; gonads normally in 4 perradial masses on manubrium, but 3–8 gonads may be present; 8 little-developed marginal bulbs, short exumbrellar cnidocyst tracks above each bulb; 2 opposite marginal capitate tentacles; without ocelli. Developmental stages. Newly released medusae with bell-shaped umbrella, slightly higher (height 0.3 mm) than wide; 4 exumbrellar rows of nematocysts; manubrium very short; 4 broad radial canals, with zooxanthellae on gastrodermis; circular canal missing; tentacles lacking. Cnidome. Atrichous isorhizas, haplonemes, and three types of stenoteles (polyp); stenoteles and telotrichous macrobasic euryteles (medusa). Distribution. Atlantic, Indo-Pacific, Mediterranean ( Moser 1925 ; Totton 1954 ; Brinckmann-Voss 1970 ; Daniel 1976 ; Bouillon 1984a ; Pagès et al. 1992 ; Schuchert 1996 ; Bouillon et al. 2004; Gravili et al. 2008a ). Records in Salento. Common and moderately frequent along the Ionian and Adriatic Apulian coasts: Tricase Porto, Torre dell’Orso, Roca, San Foca, (Gravili 2006; Gravili et al . 2008a ; F. Boero unpublished observations). Remarks. Gonothecae and medusae not seen in the present study. The adult medusae of Porpita porpita are not known from the Mediterranean; they have been described only from Papua New Guinea ( Bouillon 1984a ). References. Brinckmann-Voss (1970 , 1987 ), Bouillon (1984a) , Pagès et al. (1992) , Medel & López-González (1996) , Gravili (2006), Gravili et al . (2008a) .