Cassiopea frondosa

Cassiopea frondosa (Pallas, 1774) Distribution See Fig. 3, Mendoza-Becerril et al. (2025). Notes This species is the most morphologically distinctive member of the genus, readily identified by the presence of 12 rhopalia and by its oral appendages, which are flattened and leaf-shaped (Mayer 1910); this diagnostic character is visible in the citizen-science record shown in Fig. 2 d. These characters distinguish C. frondosa from other Cassiopea species reported from the Mexican Caribbean, which lack flattened, leaf-shaped appendages, show greater variation in appendage colour and shape and typically possess around 16 rhopalia. Previous records by Collado et al. (1988) and subsequent studies reporting this species in the Mexican Caribbean were likely correct, based on these same traits. The presence of C. frondosa in the Mexican Caribbean is, therefore, accepted as valid and the name is retained in this checklist (Fig. 2 d).