So Young Jeong1, Paul W. Gabrielson2, Guillermo Diaz-Pulido1
1Australian Rivers Institute-Coast & Estuaries, and Coastal and Marine Research Centre, School of Environment and Science, Nathan Campus, Griffith University, Australia
2Biology Department and Herbarium, Coker Hall CB 3280, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27599-3280, USA
Porolithon is a major reef building coralline genus in the shallow tropical to subtropical coral reefs. Porolithon species provide important ecosystem functions such as cementing and consolidating reef frameworks, providing food and habitat for a range of reef organisms, and facilitating settlement of coral larvae and other invertebrates. Thereby, discovering and documenting the taxonomic diversity of Porolithon species is vital to improve our understanding their ecological roles and overall marine biodiversity. In recent years, DNA sequencing studies focusing on this genus have unravelled several striking cases of cryptic diversity. In the largest coral reef ecosystem of the world, the Great Barrier Reef (GBR, Australia), however, no detailed taxonomic studies have been undertaken. The aim of this study was to document the diversity and distribution of Porolithon species using molecular and morpho-anatomical data. The molecular analyses using psbA and rbcL genes revealed extensive cryptic diversity with at least 30 Porolithon species occurring in the GBR and adjacent coral reef regions. Our study emphasises the importance of detailed observations of specimens in situ (e.g., documenting coloration with a photographic record) coupled with genetic sequencing of the specimens. Our study indicates considerable speciation of this algal genus in tropical and subtropical waters.