Grateloupia huangiae (Halymeniaceae, Rhodophyta), a new species from Taiwan previously confused with Polyopes lancifolius, with emphasis on the development of the auxiliary-cell ampullae

Grateloupia huangiae S.-M. Lin & H.-Y. Hang sp. nov. was previously recorded as G. okamurae Yamada [currently recognized as Polyopes lancifolius (Harvey) Kawaguchi & H.W. Wang] in Taiwan. Molecular phylogenetic analysis shows that G. huangiae is unrelated to P. lancifolius but is closely related to Grateloupia taiwanensis S.-M. Lin & H.-Y. Liang. Although G. huangiae superficially resembles P. lancifolius in having a leafy thallus and short proliferations borne on the thallus surface, the structure of the auxiliary-cell ampulla is very different. The auxiliary-cell ampulla of G. huangiae is composed of three orders of unbranched filaments before diploidization, each of which is 11-13 cells long. The auxiliary cell is the first cell of the third-order ampullar filament, which is cut off from the first cell of the second-order ampullar filament. This type of auxiliary-cell ampulla is the same as that found in G. taiwanensis. On the other hand, P. lancifolius has a more complex auxiliary-cell ampulla in which the ampullar filaments may bear up to five to six orders of branches before diploidization. A detailed study of the development of auxiliary-cell ampullae before and after diploidization is needed in other species and genera within the Halymeniaceae to better delineate generic concepts in the family.