Chrysaora achlyos Martin, Gershwin, Burnett, Cargo & Bloom, 1997

Morandini, André C. & Marques, Antonio C., 2010, Revision of the genus Chrysaora Péron & Lesueur, 1810 (Cnidaria: Scyphozoa) 2464, Zootaxa 2464, pp. 1-97 : 9-11

Chrysaora achlyos Martin, Gershwin, Burnett, Cargo & Bloom, 1997

( Figures 2 –8, 71, 84)

Chrysaora sp. ; Larson 1990: 549 (mention, tab. 1), 552 (mention) [south of California – USA]. Larson & Arneson 1990: 130 (mention), 131 (Tab. 1) [California – USA]. Kuck & Martin 1990: 48–49 (comments occurrence, association with fish) [Baja California – Mexico]. Martin & Kuck 1991: 89–93, 97–99 (mention), 93–96 (association with Pycnogonida, Crustacea Amphipoda, Mysidacea, Brachyura , and fish), fig. 1 (medusa swimming), fig. 2 (medusae swarm), fig. 3 (crab on exumbrella), tab. 1 (list of medusa sightings) [southern California – USA; Baja California – Mexico].

Chrysaora achlyos Martin, Gershwin, Burnett, Cargo & Bloom 1997: 9–11 (original description), figs 1–2 (medusa), fig. 3 (nematocysts) [Long Beach, Venice Beach, California – USA]. Wrobel & Mills 1998: 102, 103 (mention). Radwan, Gershwin & Burnett 2000: 1581–1591 (nematocysts toxicity), figs 1a–b (nematocysts) [California – USA]. Schaadt, Yasukochi, Gershwin & Wrobel 2001: 290–292 (life cycle), figs 1, 4, 8–9 (medusa), fig. 2 (gonads), fig. 3 (primary polyps), figs 5, 10 (strobilating polyps), figs 6–7 (ephyra) [San Diego, Los Angeles, California – USA]. Purcell & Arai 2001: 35 (tab. 4). Gershwin & Collins 2002: 128 (mention), 129 (tab. 1), 130 (mention), 131 (mention, presence of quadralinga), 132 (mention), 133 (mention), 134 (mention), 139 (mention), 142 (mention, key), fig. 1a (quadralinga), fig. 2 (phylogeny). Widmer 2008b: 78, tab. 4 (ephyrae characters). Arai 2009: 243, 244 (podocysts). Hamner & Dawson 2009: 170, 181 (mention)

Type specimens. HOLOTYPE: CMA 89.28 .1 (~ 30 cm in diameter, 28.vii.1989, female preserved in 4% formaldehyde solution in seawater, Long Beach, California – USA, on water surface, near Desmond Bridge, T. Deckel col.) . Paratypes: LACM 89 - 206.1 (medusa) [not seen] , LACM 89 - 205.1 (medusa) [not seen] , LACM 89 - 26.1 (medusa) [not seen] .

Examined material. Holotype; CASIZ 107783 (~ 35 cm in diameter, 25.xi.1966, ethanol 75%, 39º22’N 123º41’W, Fort Bragg , Mendocino, California – USA), CASIZ 167588 (~ 35 cm in diameter, female, 12.vii.1999, 4% formaldehyde solution in seawater, 39º22’N 123º41’W, La Jolla, San Diego, California – USA); LACM not-numbered (~ 36 cm in diameter, 17.vii.1999, 4% formaldehyde solution in seawater, Solana Beach, La Jolla, California – USA].

Type locality. Long Beach, southern California – USA.

Distribution. Eastern North Pacific Ocean (from southern California to Mexico) ( Fig. 71).

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

Holotype description. Specimen in poor condition, with umbrella only remaining. Umbrella hemispherical, ~ 25 cm in diameter. Exumbrellar surface smooth, transparent (maybe due to preservation). Mesoglea rigid, ~ 1.5 cm thick centrally, thinner at edge. Marginal lappets 4 per octant (2 rhopalar and 2 tentacular), squared with rounded border; with canals of gastrovascular system; rhopalar lappets slightly smaller than tentacular ones. Rhopalia 8, without ocelli, in deep clefts; exumbrellar sensory pit deep. Tentacle clefts of same octant of similar depth (aligned). Tentacles 24 (3 per octant) (only basal part observed). Subumbrellar musculature not distinguishable. Brachial disc circular, but with 4 evident corners, grooved. Pillars evident, 2 cm wide, delimiting corners of brachial disc. Subgenital ostia triangular with rounded margin, 5 cm in diameter. Oral arms absent, but thick base present. Central stomach circular, marginal region limited by insertion of radial septa. Stomach pouches 16, width uniform at basal part; tentacular pouches enlarged distally. Radial septa thin, with rounded 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. Gastric filaments not observed. Quadralinga present, with one lobe. Gonads not observed.

Description of other specimens and additional data – Medusa: medusae up to 1 m diameter ( Fig. 2); umbrella hemispherical, but flatter in younger specimens (Fig. 3). Exumbrella finely granulated (small papillae); colouration varied, from dark purple to almost black, younger specimens dark orange (in captivity) ( Figs 2 –4). Mesoglea rigid, thicker centrally. Marginal lappets (in adults) square with rounded margins, 4 per octant, with canals of gastrovascular system; rhopalar lappets slightly smaller than tentacular ones; margin of rhopalar lappets overlapping (“closed rhopalium” condition); rounded in younger specimens (~ 6 cm in diameter) but already with some canals. Rhopalia 8, without ocelli, in deep clefts; exumbrellar sensory pit deep. Tentacle clefts of same octant aligned. Tentacles 24 (adults), 3 per octant (the primary tentacle central) (Fig. 5); 3–4 times longer than umbrellar diameter; whitish to pale pink. Radial and circular musculature not discernible. Brachial disc circular, grooved in larger specimens. Pillars evident. Quadralinga present, with 1 lobe (Fig. 6). Subgenital ostia rounded to triangular, 1/10 th umbrellar diameter. Oral arms up to 6 m in length, V-shaped, with frilled free edges, spirally coiled ( Fig. 2). Central stomach circular; margin limited by insertion of radial septa. Stomach pouches 16, width uniform at basal part; tentacular pouches enlarged at 1/5 th of distal part. 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. 5). Gastric filaments in 4 interradial fields. Gonads encircling gastric filaments, forming semi-circular ring, heavily folded. Planula: no available data. Scyphistoma (Fig. 8): conical to goblet-shaped, up to 3.3 mm in height; oral disc 2.1 mm wide; tentacles typically 16 tentacles (14–18), length 3 times polyp height; mouth cruciform, with prominent lips elevated in relation to oral disc; gastric septa 4; whitish. Podocysts: trapezoid, 0.4–0.8 mm wide; yellowishbrown. Strobila: polydisc (more than 20 ephyrae), reddish, strobilation lasting almost 15 days. Ephyra (Fig. 7): typically with 8 arms (lobes); marginal lappets 16, pointed; rhopalia 8, with white concretions; 1.3 mm diameter after release; reddish; with a nematocyst concentration on each side of rhopalia (on the lappets). Cnidome ( Fig. 84): Specimen CASIZ 107783, medusa tentacles with large holotrichous O-isorhizas [n=3; 17.6– 18.6 x 13.7–17.6 µm (mean = 17.97 x 15.03 µm)]; small holotrichous a-isorhizas [n=10; 4.9–6.8 x 2.9–3.9 µm (mean = 6.17 x 3.82 µm)]; holotrichous A-isorhizas [n=7; 15.6–22.5 x 6.8–9.8 µm (mean = 20.72 x 8.26 µm)]; heterotrichous microbasic rhopaloids [n=10; 13.7–15.6 x 9.8–10.7 µm (mean = 14.60 x 10.19 µm)]. Specimen CASIZ 167588, medusa tentacles with large holotrichous O-isorhizas [n=10; 17.6–20.5 x 14.7–16.6 µm (mean = 19.50 x 15.88 µm)]; small holotrichous a-isorhizas [n=10; 4.9–6.8 x 1.9–3.9 µm (mean = 5.29 x 3.03 µm)]; holotrichous A-isorhizas [n=10; 14.7–17.6 x 8.8–10.7 µm (mean = 15.88 x 9.41 µm)]; heterotrichous microbasic rhopaloids [n=10; 10.7–13.7 x 5.8–7.8 µm (mean = 11.76 x 6.76 µm)].

Systematic remarks. Chrysaora achlyos can be distinguished from the other Pacific North-American species of the genus by the presence of quadralinga and 3 tentacles per octant. Additionally, the species apparently is restricted to warmer southern waters of California ( Wrobel & Mills 1998). The species is indistinguishable morphologically from Chrysaora plocamia (southeastern Pacific Ocean and southwestern Atlantic Ocean). We adopted a conservative position in relation to the distinction of these two species based on the arguments given by Stiasny (1937), Larson (1990) and Martin et al. (1997), that the colouration of the two species is different. Lighter colour forms noted in C. plocamia (photographic records from Chile) have not been recorded for C. achlyos .

Biological data. Although this species has been exhibited in public aquaria in the USA, detailed data are lacking concerning its development. The life cycle was described by Schaadt et al. (2001).

Etymology. achlyos : due to the dark colouration of the species and infrequent appearance, derived from the Greek achlyos (= mist, darkness, obscurity) ( Brown 1956; Martin et al. 1997).