Abstract

The red seaweed Chondracanthus chamissoi shows high morphological variability. Initially, three species were identified based on the width of the main axis of their blades. Later, all of them were included in a single species with two morphological groups. Recently, quantitative studies demonstrated the existence of two forms in C. chamissoi: f. lessonii and f. chauvinii. It was also shown that these two forms occur in sympatry, growing side by side. These forms were not associated with either a life cycle phase or the sex of the blades. This study aimed to determine whether the two forms could represent different species. We evaluated the forms' taxonomic position using COI and rbcL markers, including samples from three localities in southern Chile. All specimens shared a single rbcL haplotype, whereas the two COI haplotypes differed by four base pairs and were present in blades of both forms and life cycle phases. The two morphological types correspond to intraspecific forms. This species is of commercial importance, and its main market is aimed at human consumption with a marked preference for f. lessonii.