Molecular characterization of Caulerpa racemosa (Caulerpales, Chlorophyta) from Indonesia based on the Plastid tufA Gene

The green seaweed Caulerpa racemosa is a seaweed of high prospect that is being given emphasis by the Indonesian government. However, C. racemosa in Indonesia may include multiple species level-entity exhibiting morphological overlap and require molecular analysis for species identification. Molecular documentation of species richness of indigenous populations of C. racemosa is essential to underpin cultivar development and conservation of the species to avoid overharvesting. The present study aimed to determine the genetic diversity of C. racemosa and document the haplotype network of the specimens from four different locations (Bintan Island, Jepara, Takalar and Osi Island) using the chloroplast tufA gene. Twenty individuals from four areas were collected and amplified with the chloroplast-encoded gene tufA for species identification against publicly available data. The identification of C. racemosa based on the tufA gene showed that the species found in four locations were C. cylindracea (previously C. racemosa var. cylindracea), C. macra (previously C. racemosa var. macra), C. racemosa, and C. oligophylla (previously C. racemosa var. lamourouxii). This study records the existence of C. cylindracea in Takalar and Jepara, Indonesia for the first time. The most diverse C. racemosa species was in Osi Island, where the exploitation of this seaweed is very low. In contrast, the lowest number of C. racemosa varieties were found in Takalar, where exploitation is very high. There were only minor light variations of Caulerpa species in the tufA gene in four different sites with only four haplotypes found, and each haplotype corresponded to another species.