Mangrove-associated red algal species of the genus Caloglossa were collected from the estuarine waterbody during the low tide while adhering to pneumatophores, barks of mangrove trees and other solid substrates in the Sundarbans forest of Bangladesh in February and March (dry season), November and December (wet season), 2018. Anatomical structure, branching patterns, rhizoidal arrangements, apical cells, constriction at the node, midrib and reproductive traits were examined. In addition, only two species Caloglossa bengalensis and C. vieillardii reported in 1973, four new records for Bangladesh were found: C. adhaerens, C. beccarii, C. stipitata and C. leprieurii. While C. bengalensis was recorded from all sampling spots throughout the year, C. adhaerens was recorded during the wet season and only at the highest tidal zone where it receives more sun. C. beccarii occurred predominantly upstream away from the Bay of Bengal while C. stipitata seemed more common downstream. C. leprieurii was apparently rare and collected only in a few sites. However, C. vieillardii was not encountered during the study period. This study provided further evidence in documenting the rich diversity of epiphytic algae in the Sundarbans.