Clytia spp.

(Figs 20–22)

References consulted. Vannucci & Ribeiro 1955: 68–81, figs 1–8. Kramp 1961: 164 (as Phialidium). Pagès et al. 1992: 32–34, figs 35–36. Bouillon 1999: 430, figs 3.124–3.128. Lindner & Migotto 2002: figs 3–5. Bouillon et al. 2004: 193–196. Bouillon et al. 2006: 415–417, fig. 192. Lindner et al. 2011: 23–30, fig. 3.

Material. Municipality of Pontal do Paraná, Balneário de Praia de Leste (25º44’15”S – 48º21’60”W): 01/12/ 1997 — 2 specimens; (25º42’65”S – 48º27’85”W): 22/12/1997 — 5 specimens; (25º48’10”S – 48º04’90”W): 22/12/ 1997 — 1 specimen; (25º50’25”S – 47º55’80”W): 22/12/1997 — 2 specimens; (25º42’65”S – 48º27’85”W): 23/01/ 1998 — 4 specimens; (25º44’15”S – 48º21’60”W): 23/01/1998 — 14 specimens; (25º44’15”S – 48º21’60”W): 23/01/ 1998 — 3 specimens; (25º46’32”S – 48º12’15”W): 20/02/1998 — 4 specimens; (25º48’10”S – 48º04’90”W): 16/07/ 1998 — 22 specimens; (25º50’25”S – 47º55’80”W): 16/07/1998 — 1 specimen;(25º44’15”S – 48º21’60”W): 20/08/ 1998 — 19 specimens; (25º42’65”S – 48º27’85”W): 20/08/1998 — 15 specimens; (25º44’15”S – 48º21’60”W): 28/10/ 1998 — 1 specimen; (25º48’10”S – 48º04’90”W): 28/10/1998 — 26 specimens; (25º42’65”S – 48º27’85”W): 22/01/ 1999 — 2 specimens; (25º46’32”S – 48º12’15”W): 22/01/1999 — 1 specimen.

Reference specimens deposited. Mzusp 1524, 2 specimens, MZUSP 1500, 19 specimens, MZUSP 1511, 3 specimens. Dzoo-Cn 237, 3 specimens.

Distribution: Some species are considered cosmopolitan, such as Clytia linearis and Clytia hemisphaerica (Bouillon 1999; Lindner & Migotto 2002), but this can be attributed to the non-recognition of different, morphologically similar species (Lindner et al. 2011). Clytia Lamouroux polyps and jellyfish are common in coastal environments, and are found from the intertidal to 1000 m depth.

Distribution in Brazil. Along the entire coast (Migotto et al. 2002; Mesquita et al. 2006).

Description. Umbrella discoidal, 0.25–10 mm in diameter, slightly higher in smaller specimens and well flattened in larger ones. Velum and mesoglea thin. Short manubrium, with a square base, and without peduncle. Some medusae with the base of the manubrium stretched in varying degrees, resembling a short peduncle, possibly damage from the net-collections (Figs 20 and 22). Mouth with 4 simple lips, crenulated in larger specimens. 4 radial canals; only 2 specimens (<2%) with 5 canals and 5 manubrium lips. Medusae less than 4 mm in diameter, with gonads oval to slightly elongated on the distal third of the radial canals. The largest specimens (> 4 mm), with linear gonads along the distal ¾ of radial canals, with large oocytes (Fig. 21). Tentacular bulbs of the same size, conical, slightly elongated, with the same shape as in living specimens. No marginal cirri, tentacles hollow. Specimens less than 1 mm in diameter (<10% of total) with four marginal tentacles; 1–3 mm in diameter (~ 60% of the total) usually with eight tentacles; 3–4.5 mm in diameter (~ 20% of total) with 16 tentacles; and larger than 4.5 mm (~ 10% of total), with 24–32 marginal tentacles. Variable number of statocysts, specimens less than 2.5 mm usually with one or rarely two large statocysts between bulbs; the largest individuals usually have two statocysts.

Systematic remarks. Medusae of Clytia are easily identified among the Campanulariidae, by the typical umbrella, without gastric peduncle, hollow tentacles, and no marginal cirri or rudimentary bulbs (Bouillon et al. 2004). Individuals with the base of the manubrium stretched can be misidentified as species with a short peduncle, such as Eutonina scintilans (Bigelow). This kind of damage may occur when the animals become stuck in the mesh. Few species of Clytia are identifiable based on morphological characters of the medusae [e.g., Clytia linearis (Thornely)]. Characters such as the size, shape and position of the gonads and the number of tentacles and statocysts may have great morphological plasticity in some species, and a wide range of variation (Lindner & Migotto 2002; Bouillon et al. 2004). In the western South Atlantic, 8 species of Clytia have been found (Migotto et al. 2002; Lindner & Migotto 2002). Most mature specimens described here, with about 16 tentacles and 3 mm in diameter, resemble the description of Clytia noliformes (McCrady), which has no distinguishing characters in the medusa stage (Lindner & Migotto 2002). Other specimens, larger than 4 mm, with more than 16 tentacles, thin mesoglea, linear gonads, and often more than one statocyst between tentacular bulbs, resemble Clytia hemisphaerica (Linnaeus). The life cycle and cnidome of these species should be examined, and molecular studies should be conducted. A taxonomic revision is needed to resolve problems within the genus (Lindner et al. 2011).

Biological data. Clytia hemisphaerica may be the first hydromedusa to have its DNA completely sequenced (Houliston et al. 2011). The species is easy to obtain, cultivate, and manipulate, and has become a model among the Medusozoa, for studies on the evolution of regulatory mechanisms of cellular development and body plan (Houliston et al. 2011).