Mastigias undetermined

Mastigias sp. Distribution See Fig. 3 Fig. 4, Mendoza-Becerril et al. (2025). Notes The specimen examined shows the typical morphological characteristics of the genus Mastigias (Mayer 1910), including a hemispherical bell, absence of marginal tentacles and eight oral arms bearing three wing-like extensions along their length that terminate in club-shaped projections. In life, the medusa exhibited a light brown bell with conspicuous circular white spots. The specimen had a bell diameter of 10.5 cm. The individual was collected in Río Huache, Quintana Roo, Mexican Caribbean and is housed in ECOSUR, ZL (Table 1). Although species-level identification in this genus is difficult due to variation in colouration, exumbrellar patterning and body proportions (de Souza and Dawson (2018), our specimen was identified as Mastigias sp. 1. According to de Souza and Dawson (2018), jellyfish of this genus are naturally distributed across the tropical and subtropical Indo-Pacific, from the Fijian Islands to the western Indian Ocean and from Japan to Australia. However, non-native records have been reported in Hawaii (Eldredge and Smith 2001) and in the Caribbean and Gulf of Mexico (Bayha and Graham 2011, Bayha and Graham 2014). Molecular analyses using mitochondrial markers of specimens from Puerto Rico and Florida showed they are genetically closest to Mastigias sp. 1 from Indonesia (see Bayha and Graham (2011)). To date, Mastigias sp. 1 is the only lineage reported from the Caribbean Region and the record presented here represents the first and only confirmed occurrence of the genus in the Mexican Caribbean (Fig. 5 a).