Molecular systematics of Jania species (Corallinales, Rhodophyta) from south-eastern Australia based on cox1 and psbA DNA sequence analyses

Abstract

Taxonomy of the calcified marine red macroalgal genus Jania (Corallinales, Rhodophyta) is traditionally built on the comparative analyses of vegetative and reproductive morpho-anatomical characters. However, Jania species often display high levels of morphological plasticity leading to frequent homoplasies. Cryptic speciation and the occurrence of overlapping diagnostic characters between some species often compromises species identification based on the type method. Molecular methods represent powerful tools to help test morphology-based classifications, delineate morphologically challenging species, and solve taxonomic quagmires. A recent morphology-based taxonomic study of the genus Jania, using the type-method and focusing on the south-eastern Australian flora, recognized five species and two varieties. To test this morphology-based assessment we performed dual-marker (cox1 and psbA) phylogenetic and species delineation analyses of selected south-eastern Australia Jania herbarium specimens. Our results confirmed the molecular distinction of Jania crassa, J. micrarthrodia, J. pedunculata, J. rosea, and J. sagittata in Australia. The highly polymorphic J. rosea represents a species-complex. A group of specimens identified as Jania rosea are Corallina berteroi, which represents another species-complex in the genus Corallina. Several potentially new species were also resolved. Molecular phylogenetic analyses of Jania species from other localities around Australia and the world, including type and topotype specimens, are called for. Also, the development of new primers and potentially new markers specifically designed to better amplify and sequence contemporary and historically significant Jania specimens deposited in herbaria are crucial to obtain greater phylogenetic support on deeper nodes and improved taxonomic certainty.