New branched Porolithon species (Corallinales,Rhodophyta) from the Great Barrier Reef,Coral Sea,and Lord Howe Island |
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| Authors: | So Young Jeong Paul W Gabrielson Jeffery R Hughey Andrew S Hoey Tae Oh Cho Muhammad A Abdul Wahab Guillermo Diaz-Pulido |
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| Institution: | 1. Australian Rivers Institute-Coast & Estuaries and Coastal and Marine Research Centre, School of Environment and Science, Nathan Campus, Griffith University, Nathan, Queensland, Australia;2. Biology Department and Herbarium, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA;3. Division of Mathematics, Science, and Engineering, Hartnell College, Salinas, California, USA;4. ARC Centre of Excellence for Coral Reef Studies and College of Science and Engineering, James Cook University, Townsville, Queensland, Australia;5. Department of Life Science, Chosun University, Gwangju, South Korea;6. Australian Institute of Marine Science, Townsville, Queensland, Australia;7. Coastal and Marine Research Centre, School of Environment and Science, Nathan Campus, Griffith University, Nathan, Queensland, Australia |
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| Abstract: | Porolithon is one of the most ecologically important genera of tropical and subtropical crustose (non-geniculate) coralline algae growing abundantly along the shallow margins of coral reefs and functioning to cement reef frameworks. Thalli of branched, fruticose Porolithon specimens from the Indo-Pacific Ocean traditionally have been called P. gardineri, while massive, columnar forms have been called P. craspedium. Sequence comparisons of the rbcL gene both from type specimens of P. gardineri and P. craspedium and from field-collected specimens demonstrate that neither species is present in east Australia and instead resolve into four unique genetic lineages. Porolithon howensis sp. nov. forms columnar protuberances and loosely attached margins and occurs predominantly at Lord Howe Island; P. lobulatum sp. nov. has fruticose to clavate forms and free margins that are lobed and occurs in the Coral Sea and on the Great Barrier Reef (GBR); P. parvulum sp. nov. has short (<2 cm), unbranched protuberances and attached margins and is restricted to the central and southern GBR; and P. pinnaculum sp. nov. has a mountain-like, columnar morphology and occurs on oceanic Coral Sea reefs. A rbcL gene sequence of the isotype of P. castellum demonstrates it is a different species from other columnar species. In addition to the diagnostic rbcL and psbA marker sequences, the four new species may be distinguished by a combination of features including thallus growth form, margin shape (attached or unattached), and medullary system (coaxial or plumose). Porolithon species, because of their ecological importance and sensitivity to ocean acidification, need urgent documentation of their taxonomic diversity. |
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| Keywords: | crustose coralline algae morpho-anatomy non-geniculate coralline algae phylogeny Porolithon castellum Porolithon craspedium Porolithon gardineri psbA rbcL taxonomy type specimen sequencing |
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