The identity of Eucheuma perplexum (Solieriaceae, Gigartinales) and its distinction from Eucheuma serra as exemplified by a proposed new epitype

ABSTRACT

Eucheuma perplexum is based on specimens from Patotsu, Taiwan. This species is morphologically difficult to distinguish from other eucheumatoids that exhibit a broad range of habit forms, particularly Betaphycus gelatinus, Eucheuma denticulatum, and E. serra. Here, the Philippine and topotype specimens of E. perplexum have been examined, their distinguishing morphological features highlighted, and their phylogenetic relationships inferred from several gene sequences. Our results showed that E. perplexum is distinct from B. gelatinus and is a sister species to E. denticulatum and E. serra. Confusion also existed in a rather nebulous species circumscription of E. serra. We therefore conducted morphological and molecular taxonomic studies of conspecific specimens from Lord Howe Island, Australia. From the variety of forms there with identical DNA profiles, we propose to nominate an epitype that closely resembles Kylin’s illustration of the Mauritian holotype.

KEYWORDS:

• Carrageenophytes
• COI-5P
• cox2-3 spacer
• Lord Howe Island
• Molecular phylogeny
• Philippines
• rbcL
• Taiwan

ACKNOWLEDGEMENTS

We are grateful to Gary Saunders for providing us sequence data of Lord Howe Island E. serra. Thanks are due to Zenaida Agngarayngay and the late James Calaoagan who introduced R.V. Dumilag to sites of E. perplexum in Ilocos Norte, Philippines. S.-M Lin acknowledges Li-Chia Liu for field and laboratory assistance. G.T. Kraft thanks his many research collaborators of over 40 years’ study at Lord Howe Island, the first World-Heritage site to be declared in Australia, particularly to John A. Lewis, Christopher E. O’Brien, Drs Robert W. Ricker, John M. Huisman, Paul W. Gabrielson, Alan J.K. Millar, Gary W. Saunders, and Michael D. Guiry. We also thank our two referees, Wilson Freshwater and David Garbary, for improving the manuscript.

SUPPLEMENTARY MATERIAL

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Additional information

Funding

This research was funded by the Department of Science and Technology, Philippine Council for Agriculture, Aquatic, and Natural Resources Research and Development under the Accelerated Science and Technology Human Resource Development Program awarded to R.V. Dumilag and in part by the Ministry of Science and Technology (Taiwan) grants (NSC 102-2628-B-019-002-MY3 and MOST 104-2621-B-019-001) to S.-M. Lin. G. T. Kraft’s studies at Lord Howe Island have been underwritten by the Australian Biological Research Study, Canberra, and the School of Biosciences, University of Melbourne.