Systematic revision of the red algal genus Yonagunia (Halymeniaceae, Rhodophyta) from Taiwan, including the description of two new species

ABSTRACT

Among the eight species of Yonagunia described in the Indo-Pacific region, five species have been reported from Taiwan. In this study, we re-examined additional herbarium specimens which were morphologically similar to the other Taiwanese species of Yonagunia. Two new species of Yonagunia (Y. robusta sp. nov. and Y. stipitata sp. nov.) were identified based on rbcL sequence analyses, and their vegetative and reproductive structures were documented in detail. Yonagunia robusta is the largest species (up to 13 cm high) found in Taiwan and superficially resembles a previously described species, Y. palmata from northern Taiwan, but the thallus size is much larger and the branches are coarser in Y. robusta. Young plants of Y. stipitata may be confused with Y. maillardii, a species widely distributed in the Indo-Pacific, but the thallus branches are much thinner and numerous reproductive branchlets are formed in clusters in fertile Y. stipitata. Yonagunia robusta is widely distributed from northern to south-eastern Taiwan, whereas Y. stipitata is restricted to Orchid Island, a remote small island off the south-east of Taiwan. The species diversity (seven out of 10 described species) of Yonagunia is high in Taiwan and it is speculated that some more cryptic species will be found from the Indo-Pacific by using a combination of DNA sequence data and morphological observations.

HIGHLIGHTS

Ten species of Yonagunia have been described from the Indo-Pacific. Seven out of 10 species of Yonagunia are found in Taiwan. Cryptic species of Yonagunia will be found in the Indo-Pacific.

Acknowledgements

We thank Y.-S. Chiou for helping with DNA sequencing and our diving partners H.J. Hsueh, L.C. Liu and T.B. Shiau for collecting the specimens used in this study.

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplementary information

The following supplementary material is accessible via the Supplementary Content tab on the article’s online page at https://doi.org/10.1080/09670262.2022.2029950.

Supplementary table S1: Information of the species used in the rbcL sequence analyses.

Author contributions

C.Rodríguez-Prieto: morphological investigation, drafting and editing manuscript; Y.-C.Chuang: morphological investigation and analysis of molecular data; S.-M.Lin: original concept, morphological investigation and analysis of molecular data, drafting and editing manuscript.

Additional information

Funding

This project was mainly supported by Ministry of Science and Technology grants (Taiwan) (NSC 97-2621-B-019 -003 -MY3, NSC 102-2621-B-019 -001~MOST 104-2621-B-019-001) and partial support from Haiken Algal Foundation (107G28902) to S.-M. Lin.