Eucheilota duodecimalis A. Agassiz

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 : 304

Eucheilota duodecimalis A. Agassiz

( Figs 15–16 )

References consulted. Mayer 1910: 283–284, fig. 152. Vannucci 1960: 395–396, fig. 1. Kramp 1961: 174. Bouillon 1999: 425, fig. 3.94. Tronolone 2001: 103–106, fig. 25. Tronolone 2007: 61–62, fig. 2.25. Nogueira 2012, fig. 9.

Material. Municipality of Pontal de Paraná, Balneário de Praia de Leste: (25º44’15”S – 48º21’60”W): 01/12/ 1997 — 1 specimen; 22/12/1997 — 1 specimen; 23/01/1998 — 10 specimens; 20/02/1998 — 13 specimens; 22/01/ 1999 — 1 specimen; 24/03/1999 — 1 specimen.

Reference specimens deposited. MZUSP 1514, 5 specimens, MZUSP 1488, 1 specimen, MZUSP 1499, 1 specimen. Dzoo-Cn 235, 6 specimens.

World distribution. Western Atlantic; from the northeast coast of the United States to southern Mexico ( Mayer 1910; Suárez-Morales et al. 1995), and Brazil (Migotto et al. 2002).

Distribution in Brazil. From the state of Rio de Janeiro to Rio Grande do Sul, in coastal regions and within bays (Navas-Pereira 1980; Migotto et al. 2002; Nogueira 2012).

Description. Umbrella higher than wide, 0.5–1.3 mm in diameter, shape of the umbrella almost always conserved. Manubrium bottleneck-shaped, short, less than ¼ of the umbrellar height. Tiny mouth lips, almost fused. Four radial canals, circular canal. Gonads in the distal portion of the radial canals, females with large oocytes. Specimens larger than 0.5 mm in diameter bearing gonads. Four tentacular bulbs, usually with a pair of lateral cirri ( Fig. 16 ), and eventually more. Tentacles and cirri in most animals destroyed. Three statocysts between adjacent bulbs. Large statocysts easily viewable if margin undamaged.

Systematic remarks. Currently 18 species are recognized in the genus ( Schuchert 2013); five have been found in the South Atlantic ( Bouillon 1999) and four of these in Brazil (Migotto et al. 2002). This species is easy to identify, being very distinct from the other three Eucheilota species of the southwestern Atlantic, because of: four tentacles; 12 statocysts arrangement; absence of rudimentary bulbs; and the typical shape and position of the gonads ( Fig. 15 ). Although all the descriptions mention a single pair of lateral cirri ( Mayer 1910; Kramp 1961; Bouillon 1999), individuals were observed with two pairs, similar to the description of Tronolone (2001). Kramp (1959b) noted that the number of cirri of Eucheilota spp. may frequently vary. Young individuals, characterized by the marginal cirri ( Vannucci 1960; Tronolone 2001), were not found.

Biological data. Typical species of coastal waters, euryhaline with a preference for warmer waters (>20ºC) ( Vannucci 1963; Navas-Pereira 1981).

Figures

FIGURE 14 – 18. Cirrholovenia tetranema Kramp: lateral view (14); Eucheilota duodecimalis A. Agassiz: oral view (15) and tencular bulb with a pair or lateral cirri view (16); Eucheilota maculata Hartlaub: umbrellar margin with a conical tentacular bulb, lateral cirri (arrow), and a rudmentary bulb (17), manubrium and mouth with four black spots on the interradial walls of the manubrium (18).