Proboscidactyla ornata (McCrady)

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 : 297-299

Proboscidactyla ornata (McCrady)

( Fig. 7–8 )

References consulted. Vannucci 1957: 67–70. Kramp 1959a: 178, fig. 255. Kramp 1961: 235. Kramp 1962: 343– 347. Brinckmann & Vannucci 1965: 362–363. Goy 1979: 283, fig. 24. Correia 1983: 125, fig. 41. Bouillon 1999: 432, fig. 3.140. Tronolone 2001: 70–74, figs 17 A– E. Tronolone 2007: 51–52, figs 2.18–2.19.

Material. Municipality of Pontal do Paraná, Balneário de Praia de Leste (25º42’65”S – 48º27’85”W): 22/12/ 1997 — 5 specimens; (25º48’10”S – 48º04’90”W): 22/12/1997 — 4 specimens; (25º50’25”S – 47º55’80”W): 22/12/ 1997 —11 espécies; (25º44’15”S – 48º21’60”W): 23/01/1998 — 2 specimens; (25º46’32”S – 48º12’15”W): 23/01/ 1998 — 6 specimens; (25º50’25”S – 47º55’80”W): 23/01/1998 — 1 specimen; (25º46’32”S – 48º12’15”W): 20/02/ 1998 — 4 specimens; (25º42’65”S – 48º27’85”W): 22/04/1998 — 1 specimen: (25º44’15”S – 48º21’60”W): 16/07/ 1998 — 2 specimens; (25º50’25”S – 47º55’80”W): 25/11/1998 — 2 specimens; (25º42’65”S – 48º27’85”W): 22/01/ 1999 — 3 specimens: (25º46’32”S – 48º12’15”W): 22/01/1999 — 5 specimens; (25º48’10”S – 48º04’90”W): 24/02/ 1999 — 1 specimen; (25º46’32”S – 48º12’15”W): 24/03/1999 — 3 specimens; (25º48’10”S – 48º04’90”W): 24/03/ 1999 — 1 specimen; (25º50’25”S – 47º55’80”W): 24/03/1999 — 1 specimen.

Reference specimens deposited. Dzoo-Cn 236, 8 specimens. MZUSP 1501, 3 specimens. MZUSP 1487, 1 specimen. MZUSP 1513, 4 specimens. MZUSP 1502, 1 specimen. MZUSP 1492, 3 specimens. MZUSP 1504, 3 specimens.

World distribution. Cosmopolitan in tropical waters ( Kramp 1961). Atlantic Ocean: from New England ( USA) to Bahamas, Brazil, and West Africa. Pacific Ocean: Acapulco ( Mexico), China, and Japan. Mediterranean Sea. Indian Ocean: Maldives, India, Australia ( Kramp 1961; Bouillon et al. 2004; Kawamura & Kubota 2008).

Distribution in Brazil. Coast of Alagoas and Bahia states ( Goy 1979) and from the state of Rio Grande do Sul to Rio de Janeiro ( Thiel 1938; Vannucci 1957; Vannucci 1963; Moreira 1973; Goy 1979; Navas-Pereira 1981; Correia 1983; Tronolone 2001, 2007; Nogueira 2012).

Description. Umbrella hemispherical, 0.5–3.75 mm in diameter. Apical region with thickening of mesoglea. Base of manubrium with four gastric pouches, mouth with four lips. Medusa buds emerging on the basis of gastric pouches over the radial canals. Most specimens examined measured 0.5–1.5 mm in diameter, with 4–12 marginal tentacles, and medusa buds. The largest individual, 3.75 mm in diameter, had 16 tentacles and medusa buds, and was therefore sexually immature. Four primary radial canals, branching into 8 or more, rarely up to 20 terminal branches, in the same number of tentacles. The ramifications of radial canals can be observed only in wellpreserved specimens. Interradial clusters of cnidocysts on exumbrella connected to the margin through a hollow canal ( Fig. 8 ). Without statocysts and ocelli. Tentacular bulbs orange to brown, hollow marginal tentacles. Specimens badly damaged, still preserving the medusa buds. The general shape, coloration of tentacles and tentacular bulbs, as well as clusters of cnidocysts in the exumbrella generally are conserved and are important for identification.

Systematic remarks. Of the nine valid species of the genus ( Schuchert 2013), four occur in the South Atlantic ( Bouillon 1999) and only P. ornata in Brazil (Migotto et al. 2002). P. ornata is smaller than the other three species of the South Atlantic and differs from P. mutabilis (Browne) and P. stellata (Forbes) by having only four gastric pouches and four primary radial canals; and from P. menoni Pagès, Bouillon & Gili by having a smaller number of tentacles and terminal branches of the canals (usually 16–20 and a maximum of 45 in P. ornata and up to 60 in P. menoni ) (Kramp 1952, 1966; Pagès et al. 1992; Bouillon 1999). In Japan, medusae of P. o r n a t a with more than four tentacles, similar to those described here, are rare, and almost all the individuals found in nature are immature ( Kawamura & Kubota 2008), as also observed here. Our specimens were similar to the recently released individuals described by Tronolone (2001) and smaller than those found by Vannucci (1957), who described their specimens as being 1.1–5 mm in diameter and with 16–20 tentacles.

Biological data. Hydroids of the family Proboscidactylidae are very specialized morphologically and in their environmental requirements. They have bilateral symmetry, with only two filiform tentacles emerging below the constriction of the hypostome, and are epizoic on sabellid polychaete tubes ( Brinckmann & Vannucci 1965). Kramp (1962: 343–345, figs 7–9) described a well-developed polyp grown at the base of the stomach of one P. ornata medusa.

Figures

FIGURE 6 – 9. Turritopsis nutricula McCrady: lateral view (6); Proboscidactyla ornata (McCrady): oral view of medusae with buds on the basis of gastric pouch (7) and cluster of nematocysts on umbrellar margin (8); Corymorpha gracilis (Brooks): adult medusae, Dzoo-Cn 246 (9).