Hydromedusae (Cnidaria: Hydrozoa) from the coastal lagoon of Bocas de Dzilam, Yucatá

Background. Hydrozoan populations have an important role on the dynamic of the coastal ecosystems. However, the studies on hydromedusae in coastal lagoons from the Yucatan State are scarce. Goals. This study focuses on describe the specimens from the first taxonomic list of hydromedusae in a coastal lagoon of the State of Yucatan. Methods. Samples were obtained through circular surface trawls using a zooplankton net in the coastal lagoon of Bocas de Dzilam. Six sampling stations were established inside the lagoon and eight outside, in adjacent zones to the mouth of the lagoon. The collected hydromedusae were fixed in a 4% formalin solution and identified with specialized literature. Results. Nine hydromedusae, divided in 3 orders and 8 families were identified, from which Hydractinia carica constitutes a new record for the Gulf of Mexico; the descriptions and images of the specimens are presented in the paper. Conclusions. These results set a basis to start to understand the composition of hydromedusae in coastal lagoons of Yucatan and continue researching about this complex group. However, further research efforts are required in coastal environments of the peninsula, in order to better understand its composition and richness.