Chrysaora plocamia ( Lesson, 1830 )

Morandini, André C. & Marques, Antonio C., 2010, Revision of the genus Chrysaora Péron & Lesueur, 1810 (Cnidaria: Scyphozoa) 2464, Zootaxa 2464, pp. 1-97 : 47-48

Chrysaora plocamia ( Lesson, 1830)

( Figures 57 –62, 81, 93)

Cyanea plocamia Lesson 1830: 116–118 (original description), Pl. XII fig. 1–2 (medusa) [ Peru]. Lesson 1843: 385–386 (description).

Stenoptycha plocamia: L. Agassiz 1862: 162 (mention).

Chrysaora plocamia: Haeckel 1880: 516 (description) [ Peru]. von Lendenfeld 1884: 269–270 (description) [ Peru]. Vanhöffen 1908: 39 (mention). Mayer 1910: 580 (synoptic table). Stiasny 1937: 273–283 (description), fig. 1 (medusa oral view), fig. 2 (umbrella margin), fig. 3 (rhopalium), figs 4–6 (umbrella margin) [ Chile]. Kramp 1952: 14–15 (description) [ Peru]. Vannucci 1954: 125 (commented that C. plocamia is identical to C. hysoscella ). Kramp 1955: 296 (mention). Kramp 1961: 327 (synonymy). O’Sullivan 1982: 29 (mention). Vinogradov & Semenova 1985: 140 (host of Hyperia curticephala ) [ Peru]. Larson 1990: 549 (mention, tab. 1), 552 (mention), fig. 1G (medusa) [ Peru, Chile]. Arai 1997: 210 (association), 225 (classification). Mianzan & Cornelius 1999: 538 (description), fig. 2.16 (distribution), figs 5.13a–b (medusa) [South Atlantic Ocean]. Gershwin & Collins 2002: 128 (mention), 129 (tab. 1), 130 (mention), 143 (key), fig. 2 (phylogeny). Vera, Kolbach, Zegpi, Vera & Lonza 2004: 234 (mention, accidents), fig. 3 (medusa) [ Chile] [non Chrysaora hysoscella ( Linnaeus, 1767) ].

? Chrysaora plocamia: Vanhöffen 1888: 14 (description), 23 (brief description), 49 (distribution) [Punta Arenas, Chile]. Segura-Puertas, Suárez-Morales & Celis 2003: 9 (list) [Gulf of Mexico].

Chrysaora blossevillei var. plocamia Mayer 1910: 581 (brief description) [non Chrysaora blossevillei Lesson, 1830 ].

Chrysaora hysoscella: Vannucci & Tundisi 1962: 209–210 (mention, distribution) [Ushuaia – Argentina].

? Chrysaora hysoscella: Vannucci & Tundisi 1962: 209–210 (mention, distribution) [Puerto Melchior – Antarctica].

Holotype specimen. Not available.

Examined material. MZUSP 1000 (~ 22 cm in diameter, 11.i.2006, 4% formaldehyde solution, Puerto Madryn - Argentina); NHM 1997.1002 (specimens ~10 and 12 cm in diameter, 27.xi.1981, 4% formaldehyde solution, Puerto Madryn – Argentina); NNM 5283 (~ 30 cm in diameter, iii.1937, 4% formaldehyde solution, Toxopila – Chile).

Type locality. coast of Peru.

Distribution. South Pacific Ocean ( Peru, Chile), South Atlantic Ocean ( Argentina) ( Fig. 81).

Diagnosis. Living medusa large, up to 100 cm in bell diameter (typically 50 cm); marginal lappets (adults) squared, up to 4 per octant, with small canals (projections of gastrovascular system); tentacles 24 (3 per octant, 2-1-2); quadralinga present, non-lobed; colouration (adults) dark purple to black, some specimens whitish.

Holotype specimen description. No holotype located, and no neotype designated.

Description of other specimens and additional data. Medusa: Umbrella diameter up to 100 cm (10–30 cm in measured specimens), almost hemispherical ( Figs 57 –58). Exumbrellar surface finely granulated; colouration varied, either transparent-whitish with irregular distributed brown-reddish spots; or completely whitish; or whitish with triangular streaks radially distributed ( Figs 57 –58, 60). Mesoglea flexible, thicker centrally. Marginal lappets wide, squared, 3 per octant; all lappets of similar size, rhopalar lappets not overlapping (“open rhopalia” condition). Rhopalia 8, without ocelli, in deep clefts; deep exumbrellar sensory pit. Tentacle clefts similar in depth. Tentacles 24 (3 per octant), primary tentacle central (Fig. 61). Musculature not distinguishable. Brachial disc circular, with four evident corners. Pillars evident, delimited by insertion corners of manubrium. Quadralinga present, non-lobed (Fig. 62). Subgenital ostia, small, rounded, ca. 1 / 10 of umbrellar diameter. Oral arms up to 6 times longer than umbrellar diameter, V-shaped, delicate and much convoluted, distal portion slightly spiraled ( Figs 57 –59). Central stomach circular, marginal region limited by insertion of radial septa. Stomach pouches 16, width uniform centrally; tentacular pouches enlarged distally. Radial septa thin; rounded at base; straight up to ¼ of margin, then making an “S” (first thinning tentacular pouch, then enlarging it); ending near tentacular base at rhopalar lappet (Fig. 61). Gastric filaments in four interradial fields. Gonads outlining gastric filaments, semicircular ring, greatly folded; colour whitish to pale pink. Cnidome ( Fig. 93): Specimen MZUSP 1000, medusa tentacles with holotrichous O-isorhizas [n=10; 19.6–22.5 x 17.6–20.5 µm (mean = 21.07 x 19.11 µm)]; holotrichous a-isorhizas [n=10; 3.9–6.8 x 2.9–3.9 µm (mean = 5.39 x 3.33 µm)]; holotrichous A-isorhizas [n=4; 14.7–18.6 x 7.8–10.7 µm (mean = 16.91 x 9.06 µm)]; heterotrichous microbasic rhopaloids [n=10; 9.8–11.7 x 5.8–6.8 µm (mean = 9.99 x 6.66 µm)]; Specimen NNM 5283, medusa tentacles with holotrichous O-isorhizas [n=10; 20.5–26.4 x 16.6–23.5 µm (mean = 23.62 x 20.58 µm)]; holotrichous a-isorhizas [n=10; 3.9–5.8 x 1.9–3.9 µm (mean = 5.19 x 2.94 µm)]; holotrichous A-isorhizas [n=5; 13.7–16.6 x 5.8–8.8 µm (mean = 14.9 x 7.45 µm)]; heterotrichous microbasic rhopaloids [n=10; 9.8–13.7 x 5.8–6.8 µm (mean = 11.56 x 6.37 µm)].

Systematic remarks. This species presents an uncommon distribution pattern, occurrung on both sides of southern South America, viz. eastern South Pacific ( Peru, Chile) ( Lesson 1830; Stiasny 1937; Kramp 1952) and western South Atlantic ( Argentina) ( Mianzan & Cornelius 1999). This pattern of distribution fits with oceanographic data and circulation noted by Acha et al. (2004) and known as the Patagonian cold estuarine zone, connecting the Pacific and Atlantic oceans. No difference has been noted in specimens from these areas either by previous authors ( Stiasny 1937) or by us. There is a doubtful record of the species in the Gulf of Mexico ( Segura-Puertas et al. 2003). The species shares some similarities with C. achlyos (number of tentacles and lappets, shape of radial septa, morphology of lappets, shape of oral arms, and presence of quadralinga), and the two are distinguished only by colour pattern. Life cycle and genetic data are needed to establish the relationship between the two supposed species. Two Atlantic species also have three tentacles per octant, the hermaphroditic C. hysoscella (eastern North Atlantic, Mediterranean and North Sea) ( Russell 1970), and C. plocamia (some records in southern Argentina) ( Mianzan & Cornelius 1999). Their geographical ranges are clearly discontinuous, however, and the species are easily differentiated based on morphology of the radial septa, which in C. plocamia has the same pattern found in the species of the Pacific Ocean.

Etimology. plocamia : from the Greek plokamís, ídos or plókamos, meaning “ring of hairs” in an obvious reference to the ring of tentacles; a common term in botanical jargon.