Three sampling surveys were carried out, by SCUBA diving, in the Algarve (southern Portugal) in December 2007. A total of 57 species of gymnolaemate Bryozoa were identified. Of these, eight species were new to science (Mollia cristinae sp. nov., Hippoporina teresae sp. nov., Schizoporella spinosa sp. nov., Fenestrulina inesae sp. nov., Celleporina derungsi sp. nov., Dentiporella saldanhai sp. nov., Rhynchozoon celestinoi sp. nov. and Rhynchozoon rosae sp. nov.). Another 16 species are cited for the first time in Portuguese waters; of these, Stephanollona contracta is cited for the first time in European continental waters. Reference material deposited in several collections was also revised, and lectotypes and paralectotypes were selected for Mollia multijuncta and Dentiporella sardonica, species subjected to diverse interpretations. In addition Rhynchozoon revelatus was found to be a junior synonym of D. sardonica. The species collected in the study area reflect the existence of Lusitanian, Mauretanian and Mediterranean influences; the latter influence is of interest as the Mediterranean species found were previously considered endemic to the Mediterranean Sea and are usually found in shallow waters. Finally, a large degree of intracolonial variability was observed in some of the species studied, especially in Stephanollona armata, which may be taken into account in studies of the geographical variability and differentiation of cryptic species.