Chrysaora lactea Eschscholtz, 1829

Morandini, André C., Da, Fábio L., Silveira & Cornelius, Paul F. S., 2006, Redescription of Chrysaora lactea Eschscholtz, 1829 (Cnidaria, Scyphozoa) from the Brazilian coast, with designation of a neotype, Zootaxa 1135, pp. 29-48 : 31-36

Chrysaora lactea Eschscholtz, 1829

( Figures 1–13 )

Chrysaora lactea Eschscholtz, 1829: 81 –82, Pl. VII fig. 3. Dactylometra lactea: L. Agassiz, 1862: 126 .

Chrysaora hysoscella: Vannucci, 1954: 123 –126, Pl. VI figs 1–2. Chrysaora quinquecirrha: Goy, 1979: 291 .

non Chrysaora hysoscella (Linnaeus, 1767) .

non Chrysaora quinquecirrha (Desor, 1848) .

TYPE MATERIAL. MZUSP 897 (NEOTYPE SPECIMEN): São Sebastião, São Paulo state, Brazil, 17.xi.1998, on water surface, near oil terminal, J.M. Oliveira col., 1 female specimen preserved in 4% formaldehyde solution in sea water.

EXAMINED MATERIAL (see details in Appendix). MNHN Inv. M. 1715 (as C.

hysoscella ), 1716 (as C. quinquecirrha ); MNRJ 181, 182, 961, 1027, 1028, 1030, 1032, 1033, 1034, 1035, 1221, 1361, 1668, 1673, 1674, 1675, 1676, 1677, 1678, 1681, 1694, 1941, 2791, 2793, 2794, 3237; MZUSP 340, 341, 342, 361, 362, 363, 364, 365, 474, 764, 778, 791, 797, 799, 802, 803, 804, 807, 809, 811, 822, 824, 825, 826, 828, 829, 830, 1125, 1126, 1127, 1129, 1130, 1133, 1150, 1151, 1152, 1153, 1154, 1155, 1156, 1157, 1158, 1161, 1164, 1175, 1182, 1187, 1188, 1189, 1190, 1192, 1230, 1241, 1258, 1260, 1261, 1265, 1266, 1267, 1271, 1275, 1277, 1283, 1287, 1288, 1289, 1290, 1297, 1298, 1300, 1303, 1304, 1305, 1308, 1311, 1312, 1313, 1314; NHM 1997.998, 1997.999, 1997.1000, 1997.1001; ZMH C11673, ZMH C11674.

TYPE LOCALITY. Guanabara Bay, Rio de Janeiro, Brazil.

DISTRIBUTION. Western Atlantic, from Jamaica to the northern coast of Argentina. DIAGNOSIS. Live and preserved medusae average 6–11 cm in diameter (maximum recorded size 25 cm in diameter). Coloration: exumbrella background usually milkywhite, some specimens with small brown spots on exumbrella and oral arms, other specimens with a radial pattern of brownish triangles. Mature specimens varied in tentacle number, 3–5 tentacles per octant, the central one being the primary, the two peripheral ones the secondaries, and in the gaps between the two tertiaries.

DESCRIPTION OF NEOTYPE SPECIMEN. Umbrella almost hemispherical, diameter 10 cm. Exumbrellar surface finely granulated ( Figure 2 ), transparent­whitish. Mesoglea flexible, about 1 cm thick on central portion, thinning towards margin. Marginal lappets round, sharper at tip, 6 per octant (2 rhopalar and 4 tentacular); rhopalar lappets slightly longer and broader than tentacular ones. Rhopalia 8, without ocelli, in deep clefts; exumbrellar sensory pit deep, blind­ended ( Figure 3 ). Tentacle clefts varied in depth ( Figures 2 and 4 ). Tentacles 40 (5 per octant), as long as bell diameter (longer in life); arranged as 2­3­1­3­2 (central primary, secondaries laterally and tertiaries in the spaces between them) ( Figure 4 ). Subumbrellar and tentacular musculature not discernible. Mouth­disc circular, but with four evident corners, grooved. Evident pillars, 2.5 cm wide, delimited by corners of insertion of manubrium. Subgenital ostia oval, 0.5 cm in diameter. Oral arms ca. 7 cm long, V­shaped in cross section, edges delicate and convoluted, distal portion slightly spiral, distal 1/3 with reduced V­shaped free edge in cross section ( Figure 5 ). Central stomach circular, marginal region limited by insertion of radial septa. Stomach pouches 16, width uniform centrally; tentacular pouches enlarged distally. Septa narrow, wider at proximal end (pear­shaped); outer 1/3 bending towards rhopalia (~ 45º) ending straight into the margin ( Figure 4 ), proximal region of the radial septa hard to see, due to enlarged mouth­disc. Gastric filaments in four interradial fields. Quadralinga absent. Gonads rimming gastric filaments, in semicircle, greatly folded; female.

VARIATION FROM NEOTYPE AND ADDITIONAL DATA. Medusa: Umbrella diameter up to 25 cm, almost hemispherical, flat in young specimens (0.5–3 cm), varied in preserved specimens. Some specimens with small irregular papillae on exumbrella and oral arms ( Figures 1 , 2 and 3 ). Coloration highly variable ( Figure 6 ), transparent­whitish background with irregularly distributed small reddish­brown spots (warts); completely whitish; milky white background with a radial pattern of brownish triangles and irregularly distributed small reddish­brown spots (papillae) (see also Morandini et al., 2005, fig. 8 for different colour patterns). Marginal lappets round, 2–6 per octant (young having 2 and reaching up to 6); rhopalar lappets slightly wider than tentacular. Rhopalia yellowish (in vivo). Tentacles up to 40 (5 per octant); arranged as 2nd­3rd­1st­3rd­2nd (central primary, secondaries laterally and tertiaries in the spaces between them). Pillars coloured in some specimens strongly reddish­brown or with irregularly distributed small reddish­brown spots. Colour of gonads variable: whitish, yellowish­brown to pale pink. Planula. Elongate, pear­shaped; 0.14–0.2 mm long, 0.06–0.09 mm wide; whitish.

Scyphistoma ( Figure 7 ). Conical to goblet­shaped, up to 2.2 mm high; oral disc up to 1.2 mm wide; tentacles of scyphistoma typically 16 (12–21), length up to 5 times polyp height; mouth cruciform, with prominent lips elevated from the oral disk; gastric septa 4; whitish to cream. Podocysts. Trapezoid, diameter 0.2–0.3 mm, height 0.08–0.1 mm; yellowish brown. Strobila ( Figure 8 ). Polydisc (2–10 ephyrae), whitish, lasts about 10 days. Ephyra ( Figure 9 ). Typically 8 arms (lobes); 16 pointed marginal lappets; 8 rhopalia, with light yellowish concretions; mouth cruciform; diameter 1 mm just after liberation; transparent; with one nematocyst cluster on each side of rhopalium. Cnidome ( Figure 10 ). Holotrichous isorhizae present in medusae (tentacles and gastric filaments), ephyrae, and polyps; birhopaloids type II (quoted formerly as heterotrichous microbasic euryteles) present in medusae (tentacles and gastric filaments) and polyps (detailed measurements are presented in Morandini et al., 2004, tab. 2).

SYSTEMATIC REMARKS. Some individuals remain in the three­tentacled stage for the entire adult life span. The majority of the specimens collected in estuarine areas of São Paulo state had three tentacles per octant (from the 175 specimens from estuarine areas, only 7 had more than 3 tentacles per octant — see Appendix).

DEVELOPMENT. Eight­tentacled medusa: in laboratory cultures, development of the first tentacles ( Figure 9 ) occurs when ephyrae are 0.3–0.4 cm wide, reaching up to 2 cm bell diameter. 24­tentacled medusa: specimens from the wild, 1.3 cm in diameter, already had the buds of secondary tentacles. In laboratory cultures, development of the secondary tentacles ( Figure 11 ) occurs in ephyrae 2–6 months after release from the strobila, when ephyrae range from 2.5–6 cm wide ( Figure 12 ). 40­tentacled medusa: some specimens already have the maximum number of tentacles (40), apparently not related to size or maturity (one specimen 10 cm in diameter already had 5 tentacles in every octant). The final pattern of arrangement of marginal tentacles in each octant is: a single long median, primary tentacle, then two secondary tentacles similar in size next to the rhopalia (edge of the gastric pouches), and finally two tertiary tentacles with one on each side between primary and secondaries, these being typically smaller. The development of the tertiary tentacles in the species occurs in the subumbrellar portion of the lappet between the primary and secondary tentacles, thus they develop on the subumbrella and the single lappet gradually ruptures to “be converted into” two separate lappets ( Figure 13 ). In a few specimens, averaged 6–11 cm in bell diameter, 6–7 tentacles per octant were noted. Therefore, there is no direct correlation between size and number of tentacles. The beginnings of the gonads appear in specimens from 4.5 to 6 cm in diameter. Maturation, i.e. gonad development, is not directly proportional to observed size, nor is maximum tentacle number per octant.

Figures

FIGURE 1. Side view of an adult medusa (bell diameter 12 cm) of Chrysaora lactea. Note the shape of the umbrella, the colour pattern, and only 3 tentacles per octant. Specimen photographed in an aquarium.

FIGURE 2. Diagrammatic exumbrellar view of adult medusa of Chrysaora lactea. Note the arrangement of the tentacles (5 per octant) and papillae on exumbrella.

FIGURE 3. Side view of a medusa (bell diameter 9 cm) of Chrysaora lactea (with 3 tentacles per octant). Note the papillae on the exumbrella and damaged mouth arms, the colour pattern, and the exumbrellar sensory pit on the left side. Specimen photographed by Dr Alvaro E. Migotto (CEBIMar­USP) in aquarium.

FIGURE 4. Diagrammatic subumbrellar view of a typical octant of an adult medusa of Chrysaora lactea. Note the shape of the tentacular pouches and arrangement of tentacles on the margin. Note also the pear­shaped inner margins of the radial septa (white). The dark portion represents the gastrovascular cavity.

FIGURE 5. Diagrammatic side view of an oral arm of an adult medusa of Chrysaora lactea. Note the V­section, frilled edge and spiral distal portion.

FIGURE 6. Exumbrellar view of some colour patterns observed in Chrysaora lactea. Scale = 10 cm.

FIGURE 7. Side view of a polyp of Chrysaora lactea. Height approximately 2 mm.

FIGURE 8. Side view of an advanced strobila of Chrysaora lactea, showing development of chain of ephyrae at different stages. Note that the tentacles of the polyp have already regenerated. Height approximately 1.5 mm.

FIGURE 9. Oral view of an ephyra of Chrysaora lactea, 1.8 mm in diameter, showing development of the primary tentacles on the subumbrellar portion near the margin.

FIGURE 10. Nematocyst complement of different stages in the life cycle of Chrysaora lactea. A – D: scyphistoma; E – H: ephyra; I – N: medusa (tentacle). A – B, E – F, G – H, K – L: undischarged and discharged holotrichous isorhizae; C – D, I – J, M – N: undischarged and discharged birhopaloids, type II (as heterotrichous microbasic euryteles in Morandini et al., 2004). I, K and M photographed in preserved specimen, all others in living ones. Scale = 15 µm.

FIGURE 11. Oral view of a young medusa of Chrysaora lactea reared in laboratory, showing development of the secondary tentacles (arrows) on the subumbrellar portion of the marginal lappets. Scale = 0.5 mm.

FIGURE 12. Side view of a young medusa (bell diameter 4 cm) of Chrysaora lactea. Note the length of the mouth arms (with some Artemia nauplii inside). Specimen reared in laboratory and photographed in aquarium.

FIGURE 13. Oral view of a young medusa of Chrysaora lactea reared in laboratory, showing developed tertiary tentacle (arrow) between primary (central) and secondary (lateral, closer to the rhopalium). Scale = 1.5 cm.