Chrysaora, Lesueur Peron & Lesueur, 1810

Morandini, André C. & Marques, Antonio C., 2010, Revision of the genus Chrysaora Péron & Lesueur, 1810 (Cnidaria: Scyphozoa) 2464, Zootaxa 2464, pp. 1-97 : 74-75

Key to species of Chrysaora and related genera

The key was constructed to include valid species and nomina dubia of the genus Chrysaora , and excluding C. caliparea . It applies only to the medusa stage, and generally to specimens approaching 10 cm in diameter or larger. Some species developing more than 24 tentacles are difficult to identify from external morphology. A study of the cnidome may help in some cases (see above), but observations on life cycles are extremely relevant (especially for differing C. lactea from C. quinquecirrha ).

1 Pelagiid medusae (gastrovascular cavity without canals) with 8 rhopalia................................................................... 2

- Pelagiid medusae with 16 rhopalia ..................................................................................................... Genus Sanderia

2 Pelagiid medusae with 8 tentacles .............................................................................................................................. 3

- Pelagiid medusae with more than 8 tentacles .............................................................................................................. 4

3. Pelagiid medusae with 16 marginal lappets ........................................................................................... Genus Pelagia

- Pelagiid medusae with 32 marginal lappets (sometimes resembling 16, but with a thin membrane in the cleft between ......................................................................................................................................... Chrysaora colorata

4 Septa straight centripetally, then thinning and widening centrifugally (“Pacific” pattern, see Figs 1, 5 12, 15, 26, 49, 54, and 61) .................................................................................................................................................................. 5

- Septa straight centripetally, then widening centrifugally (“Atlantic” pattern, see Figs 22, 32, 41, and 65) .............. 10

5 Marginal lappets with gastrovascular canals ............................................................................................................... 6

- Marginal lappets without gastrovascular canals ......................................................................................................... 8

6 Medusae without quadralinga .................................................................................................... Chrysaora melanaster

- Medusae with quadralinga (see Figs 6, 16, and 62) .................................................................................................... 7

7 Tentacles with holotrichous O-isorhizas 19.6–26.4 x 16.6–23.5 µm; holotrichous A-isorhizas 13.7–18.6 x 5.8–10.7 µm; geographical range in the South Pacific and South Atlantic Oceans; generally lighter exumbrella with darker pattern ........................................................................................................................................... Chrysaora plocamia

- Tentacles with holotrichous O-isorhizas 17.6–20.5 x 13.7–17.6 µm; holotrichous A-isorhizas 14.7–22.5 x 6.8–10.7 µm; geographical range in the North Pacific Ocean, darker exumbrella......................................... Chrysaora achlyos

8 Medusae with 24 tentacles; chestnut colouration, with faint stripes on exumbrella .................. Chrysaora fuscescens

- Medusae with more than 24 tentacles; colouration varied, but with distinct stripes on exumbrella ........................... 9

9 Tentacles with holotrichous O-isorhizas 13.7–29.4 x 12.7–24.5 µm; geographical range in the China Sea, Philippines, and Indonesia....................................................................................................................... Chrysaora chinensis

- Tentacles with holotrichous O-isorhizas 8.8–9.8 x 6.8–7.8 µm; geographical range around Japan............................... ......................................................................................................................................................... Chrysaora pacifica

10 Mature specimens with 24 tentacles ........................................................................................................................... 11

- Mature specimens generally with 40 tentacles ......................................................................................................... 12

11 Mature specimens hermaphroditic (with egg sacs on the gastrovascular cavity ....................... Chrysaora hysoscella

- Mature specimens with separate sexes............................................................................................. Chrysaora kynthia

12 In each octant, a crescentic row of vacuoles at the base of the central tentacle ............................ Chrysaora wurlerra

- In each octant, base of the central tentacle without vacuoles .................................................................................. 13

13 In specimens with 40 tentacles, development as 2-3-1-3-2 ............................................................. Chrysaora lactea

- In specimens with 40 tentacles, development as 3-2-1-2-3 ...................................................................................... 14

14 Medusae occurring in the Atlantic Ocean ................................................................................................................... 15

- Medusae occurring in Australia................................................................................................ Chrysaora pentastoma

15 Medusae occurring on the east coast of USA...................................................................... Chrysaora quinquecirrha

- Medusae occurring on the west coast of Africa ............................................................................... Chrysaora fulgida