Molecular phylogeny of foliose Halymenia and Austroepiphloea (Halymeniaceae, Rhodophyta) from the Indo-Pacific, with the description of Halymenia taiwanensis sp. nov.

ABSTRACT

Many species of Halymenia from the Indo-Pacific have been described in the past decade, but their phylogenetic relationships are not well discussed. In this study, we inferred these relationships for the available species of Halymenia with an emphasis on the foliose species from the western Pacific Ocean and Western Australia based on rbcL and nuclear-encoded LSU rDNA sequence analyses. Our analyses show that most foliose Halymenia from the Indo-Pacific are clustered in a natural assemblage that also includes a new species (Halymenia taiwanensis sp. nov.) found in northern Taiwan, as well as the monospecific genus Austroepiphloea (single species A. bullosa) from Western Australia. The architecture of carpogonial branch (composed of a two-celled carpogonial branch and two orders of ampullar filaments, and a basal, nutritive cellular cluster) and auxiliary cell ampullae in Halymenia taiwanensis is similar to that found in the generitype H. floresii. We therefore propose the new combination Halymenia bullosa comb. nov. (basionym Schizymenia. bullosa), a species closely related to H. taiwanensis both genetically and morphologically. However, H. taiwanensis can be separated from H. bullosa by its thinner blades and surface bladelets, and by lacking a long cartilaginous stipe. Based on the rbcL phylogeny, most foliose Halymenia are seemingly more range-restricted than previously thought, except for a few species that are shown to have a wide distribution in the Western Pacific and Indian Oceans. In addition, H. dilatata, a species widely recorded in the Western Pacific Ocean, may include cryptic species and requires further investigation.

KEYWORDS:

• Australia
• Cystocarp development
• Halymenia bullosa comb. nov.
• Nuclear-encoded LSU rDNA
• rbcL
• Taiwan

ACKNOWLEDGEMENTS

We thank Y.-S. Chiou for helping with DNA sequencing and our diving partners H.J. Hsueh and L.C. Liu for collecting the specimens used in this study. John Parnell (TCD) kindly provided the image of TCD0011815 (Fig. 2).

DISCLOSURE STATEMENT

No potential conflict of interest was reported by the authors.

SUPPLEMENTARY MATERIAL

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Additional information

Funding

This work was mainly supported by Ministry of Science and Technology grants (Taiwan) [NSC 102-2621-B-019 −001~MOST 104-2621-B-019-001, MOST 110-2621-B-019-002] and partial support from Haiken Algal Foundation [107G28902 & 111G28902] was awarded to S.-M. Lin.