Molecular and morphological characterisation of Ulva chaugulii, U. paschima and U. ohnoi (Ulvophyceae) from the Persian Gulf, Iran

Abstract Species of Ulva are distributed worldwide in various aquatic habitats and their morphological characters change considerably in response to environmental conditions, which makes identification in this genus problematic. All Ulva species so far described from the Persian Gulf, Iran, have been identified by classical taxonomic methods. In this study, Ulva spp. collected from the Persian Gulf were identified by combined morphological and molecular methods. We sequenced the internal transcribed spacer ITS2 and the rbcL gene in 15 specimens, representing typical morphotypes of over 50 samples. Maximum likelihood, maximum parsimony and Bayesian inference (BI) phylogenetic reconstructions using ITS and rbcL revealed clades, which we identified as Ulva chaugulii, U. paschima and U. ohnoi. These three species have not been recorded from the Persian Gulf, Iran before. The morphology of U. chaugulii differed considerably from its species description, showing further evidence for extreme intraspecific variation in morphology in this cosmopolitan genus.