Parasite diversity and regional variation in invasive red lionfish Pterois volitans

The invasion of the red lionfish Pterois volitans in the western Atlantic has generated widespread concern due to its strong negative effects on native biodiversity. Nevertheless, information on the parasite assemblages associated with this invasive fish and their spatial variability remains scarce. Here, we examined 829 individuals of P. volitans collected from 50 coral reef sites in the Mexican Caribbean (MXC) and one in the southern Gulf of Mexico (SGMX). Across these sites, 27 parasite taxa were recorded (27 in the MXC and 8 in the SGMX), most of which were host-generalist species. Among them, five constitute new geographical records and 21 represent new host records. Trematodes were the dominant group in both locations. Overall, parasite richness ranged from 1–15 species/site, and mean intensity from 1–5.6 individuals/host. The higher parasite richness in P. volitans from the MXC and SGMX, compared with locations in its native range, suggests its integration into western Atlantic parasite networks, surpassing the initial ‘enemy release’ stage. A similarity analysis indicated that the MXC parasite assemblage was more closely related to those from the southern and southwestern Gulf of Mexico than those from the northern Gulf of Mexico, Cayman Islands, Bahamas, and Puerto Rico, likely reflecting environmental differences, geographic distances and variation in prey composition (potential intermediate hosts). At the local scale, variation among MXC sites was associated with spatial distance and the heterogeneous distribution of adjacent habitats. These findings highlight the rapid incorporation of P. volitans into local ecological interactions and its potential influence on parasite transmission dynamics in western Atlantic reef ecosystems.