Gracilaria khanjanapajiae sp. nov. (Gracilariales, Rhodophyta) from the Andaman coast of Thailand

Taxonomy and diversity of the Gracilariaceae has been increasingly investigated by using integrated morphological and genetic approaches. The Indo-Pacific is likely a hotspot for diversity of these macroalgae. Collections of flattened Gracilaria samples from Natai beach, Andaman coast of Thailand, were morphologically and genetically analysed. Our results clearly indicated the presence of a new species, G. khanjanapajiae sp. nov., in Thailand. In comparison to other known Indo-Pacific flattened species, G. khanjanapajiae can be distinguished by its dentate blade margin, deep spermatangial conceptacles (verrucosa-type) and numerous lateral and basal nutritive filaments within mature cystocarps. This new species resembles G. srilankia in having similar branching pattern and male reproductive structures, but differs in blade margin features. Phylogenetically, G. khanjanapajiae was more closely related to G. spinulosa from Taiwan than other Thai and Indian Ocean species. This present study highlights the continuing discovery of Gracilaria diversity and distribution in the tropical Indo-Pacific.