Porpita porpita Linnaeus 1758
Creators: name: Gravili, Cinzia
name: Vito, Doris De
name: Camillo, Cristina Gioia Di
name: Martell, Luis
name: Piraino, Stefano
name: Boero, Ferdinando
Publisher: name: Zenodo
Year: 2015
Subjects: Biodiversity
Taxonomy
Animalia
Cnidaria
Hydrozoa
Anthoathecata
Porpitidae
Porpita
Porpita porpita

description: 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.
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Porpita porpita occurs in May, June, September–October (Lo Bianco 1909; Tregouboff & Rose 1957); July–August (F. Boero unpublished observations).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).
description: Published as part of 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, pp. 1-187 in Zootaxa 3908 (1) on pages 64-66, DOI: 10.11646/zootaxa.3908.1.1, http://zenodo.org/record/242729