Gossea brachymera Bigelow

Nagata, Renato Mitsuo, Júnior, Miodeli Nogueira & Haddad, Maria Angélica, 2014, Faunistic survey of Hydromedusae (Cnidaria, Medusozoa) from the coast of Paraná State, Southern Brazil, Zootaxa 3768 (3), pp. 291-326 : 310

Gossea brachymera Bigelow

( Fig. 24–26 )

References consulted. Russell 1939: 707–710, figs 1–3. Kramp 1957: 42–45, fig. 8, pl. 5, figs 2–3. Kramp 1959a: 177, fig. 254. Kramp 1961: 225. Kramp 1968: 105, fig. 285. Bouillon 1978: fig. 12. Bouillon 1999: 432, fig. 3.135; Nogueira 2012: 14–15, figs 37–40.

Material. Municipality of Guaratuba (25°54’S; 48°23’W): 08/08/2003 — 68 specimens; 20/09/2003 — 15 specimens; 01/11/2003 — 1 specimen; 16/01/2004 — 1 specimen; 12/05/2004 — 2 specimens; 18/08/2004 — 5 specimens; (25º53’S; 48º32’W): 03/09/2006 — 54 specimens; 23/09/2006 — 17 specimens.

Reference specimens deposited. MZUSP 907, 4 specimens; MZUSP 908, 2 specimens.

World distribution. Northern Gulf of Mexico and Pacific coast of Mexico (Russell 1938; Segura-Puertas et al. 2003), Strait of Magellan ( Kramp 1957), Argentina ( Vannucci & Tundisi 1962; Genzano et al. 2008) and Brazil (Migotto et al. 2002).

Distribution in Brazil. From the state of Paraná to Rio Grande do Sul (Navas-Pereira 1981; Nogueira 2012; this study).

Description. Umbrella hemispherical, 5–20 mm in diameter, and 5–20 mm in height. Evident gastric peduncle, broad, pyramidal, which occupies about half the height of the subumbrellar cavity. Mouth with 4 perradial lips, well developed, provided with many nodules of nematocysts along its margin. Four radial canals, simple and obvious. Gonads wavy, over the canal from the base of the peduncle until near the circular canal, hanging on the distal portion ( Figs 24, 25 ). A total of 32 protuberances of different sizes on the umbrella margin. The 4 interradial and 4 perradial protuberances are the most developed; each has a developed tentacle, and by its side, a dwarf tentacle, and internally a closed statocyst ( Fig. 26 ). The 8 adradial protuberances are smaller, with only one developed tentacle. The other 16 protuberances, each with a developed tentacle interspersed with a dwarf tentacle. Dwarf tentacles solid, with a nematocyst button at the end, and several nematocyst rings along the length, except at the base.

Systematic remarks. Four species of the genus are considered valid ( Bouillon & Boero 2000; Schuchert 2013). Among them, G. brachymera is easily recognizable by the pattern of tentacles, the presence of a developed tentacle flanked by a dwarf in the inter- and perradial positions, and by the evident gastric peduncle. The specimens with well-developed gonads are larger than reported in most other studies: 4.5–7.5 mm (Russell 1938), 2–6 mm ( Vannucci & Tundisi 1962), except for those analyzed by Kramp (1957) from the Strait of Magellan, which also reached 2 cm in diameter. This medusa passes through considerable morphological changes during its growth; young specimens do not have the gastric peduncle, have fewer tentacles and the mesoglea is considerably thinner ( Nogueira 2012).

Figures

FIGURE 19 – 26. Eucheilota paradoxica Mayer: lateral view, radial canal with medusa bud (19); Clytia sp. Lamouroux: adult medusae with the base of the manubrium stretched, possible a sampling damage (20); adult medusae in oral view, linear gonads along radial canals (21), and a detail of the stretching of the base of manubrium (22); Obelia sp. Péron & Lesueur: oral view, specimen with 5 radial canals (23); Gossea brachymera Bigelow: adult medusae (24) detail of gonads (25), and marginal tentacles (26).