New distributional record of <i>Stephanolepis diaspros</i> (Teleostei: Monacanthidae) in the eastern Indian Ocean

A specimen of the reticulated leatherjacket, Stephanolepis diaspros Fraser-Brunner, 1940, primarily distributed in the Red Sea and Mediterranean Sea, was recorded for the first time from the southeast coast of Bangladesh. This represents the first confirmed occurrence of the species in the eastern Indian Ocean. Species identification was verified through an integrative taxonomic approach combining morphological examination, radiographic imaging and mitochondrial cytochrome c oxidase subunit I (COX1) gene sequencing. Distinctive scale patterns were observed on different parts of the body; notably, the presence of cycloid scales associated with bristles was documented as a novel diagnostic feature. Both morphometric and genetic analyses demonstrated a high similarity to previously described S. diaspros specimens, with minimal intraspecific genetic divergence (0.16%-0.33%) relative to Mediterranean populations. This new distribution record extends the known biogeographical range of S. diaspros, suggesting potential ecological plasticity and long-distance dispersal in response to environmental changes.