Ectopleura dumortieri (Van Beneden)

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 : 300-301

Ectopleura dumortieri (Van Beneden)

( Fig. 10 )

References consulted. Russell 1953: 76–79, fig. 33 A– D. Kramp 1961: 34. Bouillon 1999: 420, fig. 3.68. Tronolone 2001: 80–83, fig. 19. Bouillon et al. 2004: 105, fig. 55, G– J. Tronolone 2007: 53–54, fig. 2.20; Nogueira 2012, fig. 7.

Material. Municipality of Pontal do Paraná, Balneário de Praia de Leste: (25º44’15”S – 48º21’60”W): 01/12/ 1997 — 1 specimen; (25º46’32”S – 48º12’15”W): 01/12/1997 — 2 specimens; (25º42’65”S – 48º27’85”W): 22/12/ 1997 — 3 specimens; (25º46’32”S – 48º12’15”W): 22/12/1997 — 1 specimen; (25º48’10”S – 48º04’90”W): 22/12/ 1997 — 1 specimen; (25º48’10”S – 48º04’90”W): 20/02/1998 — 2 specimens; (25º48’10”S – 48º04’90”W): 31/03/ 1998 — 5 specimens; (25º42’65”S – 48º27’85”W): 22/04/1998 — 1 specimen; (25º42’65”S – 48º27’85”W): 24/06/ 1998 — 1 specimen; (25º42’65”S – 48º27’85”W): 20/08/1998 — 5 specimens; (25º46’32”S – 48º12’15”W): 02/10/ 1998 — 32 specimens; (25º48’10”S – 48º04’90”W): 02/10/1998 — 6 specimens.

Reference specimens deposited. Dzoo-Cn 239, 5 specimens. MZUSP 1490, 3 specimens. MZUSP 1498, 1 specimen.

World distribution. In the three great oceans, mainly in tropical and subtropical regions, and extending toward cooler regions north and south ( Kramp 1961; Santhakumari et al. 1997; Ballard & Myers 2000; Bouillon et al. 2004). In the western Atlantic, from New England ( USA) to Panama ( Kramp 1961; Miglietta et al. 2008), and Brazil (Migotto et al. 2002).

Distribution in Brazil. From the state of Rio de Janeiro to Rio Grande do Sul (Migotto et al. 2002).

Description. Umbrella almost spherical, 0.25–0.9 mm in diameter. Thick mesoglea with an apical thickening. Specimens very wrinkled and contracted, with mean size (0.5 mm height) smaller than the sizes mentioned by Bouillon (1999) and Russell (1953) (2–3 mm). Short apical canal in a few individuals. Four radial canals and circular canal. Exumbrella with eight longitudinal cnidocyst rows, arranged in four pairs, extending from the tentacular bulbs to the apex (sometimes not reaching the apex). Manubrium long, extending to the umbrella margin ( Fig. 10 ), or exceeding it. Simple and tubular mouth, armed with cnidocysts. In contracted specimens the manubrium almost fills the subumbrellar cavity. Gonads surrounding the manubrium, leaving the mouth free. Four brown tentacular bulbs. Very extendable tentacles, with clusters of cnidocysts on abaxial surface ( Fig.10 ). Tentacles usually coiled to each other.

Systematic remarks. Schuchert (2013) listed 31 species in the genus. However, most of the nominal species have been described only by part of their life cycle, such as the hydroid, newly released medusae, or adults ( Bouillon & Boero 2000). Rearing experiments are thus necessary to elucidate the life cycles of the species ( Bouillon & Boero 2000). Genetic studies also have the potential to clarify species by linking different life-cycle stages ( Miranda et al. 2010). Only two species from the South Atlantic and Brazil known to produce medusae ( Bouillon 1999; Migotto et al. 2002). E. dumortieri can easily be distinguished from E. obypa Migotto & Marques by the presence of four tentacles in the first and only two in the second ( Migotto & Marques 1999). Russell (1953) commented that E. dumortieri slightly differentiates in the course of its development, and that newly released medusae are about 1 mm in height. In Brazil, specimens studied by Vannucci (1957) and Tronolone (2001), slightly larger than 1 mm, already had well-developed gonads, similar to the animals found in this study.

Biological data. The species was more abundant in the winter months, especially August 1998. Migotto (1996) described the life cycle of populations from the Brazilian coast. The polyp is known in Paranaguá ( Altvater 2009), Cananéia ( Vannucci 1963), and São Sebastião ( Migotto 1996). The medusa is euryhaline, occurring in estuaries such as Cananéia ( Vannucci 1957, 1963), Paranaguá (R. Nagata pers. obs.), and São Francisco do Sul ( Nogueira 2012).

Figures

FIGURE 10 – 13. Ectopleura dumortieri (Van Beneden): lateral view (10); Aequorea forskalea Péron & Lesueur: umbrellar margin, disposition of marginal tentacules and radial canals (11) and tentacular bulb (12). Rhacostoma atlanticum L. Agassiz: oral view, rows of gelatinous papillae between radial canals, one radial canal branching (13).