First Verified Record and Morpho-Ecological Characterization of Bunodosoma cavernatum (Cnidaria: Actiniaria) in Cartagena Bay, Colombian Caribbean

Bunodosoma cavernatum (Bosc, 1802) is a morphologically variable actinian species widely distributed in the Western Atlantic, yet poorly documented in Colombia. This study provides the first confirmed record of B. cavernatum in Cartagena Bay (Colombian Caribbean), extending its known distribution to a highly modified estuarine environment. The objectives were to (1) confirm the taxonomic identity of the species and characterize its external morphology, internal anatomy, histology and cnidome; (2) compare these traits with previously published Caribbean descriptions; (3) describe behavioral observations under controlled aquarium conditions; and (4) assess the abundance, microhabitat preferences and biological associations within the study area. Specimens were collected from shallow, sediment-rich substrates influenced by freshwater input from the Dique Channel. Diagnostic features were consistent with prior Caribbean descriptions. However, we report expanded cnidome size ranges and spirocysts in several tissues, not previously reported. Behavioral observations revealed rapid acclimation, consistent daily activity cycles, and sperm release associated with thermal variation (25–28 °C). Population density reached 32.2 individuals/m2, with an aggregated distribution around rocky or artificial substrates. These findings expand current knowledge of the ecological and reproductive plasticity of B. cavernatum in anthropogenically impacted tropical coastal ecosystems.