Quite an oddity: new worldwide records of Renouxia (Rhodogorgonales, Rhodophyta), including R. marerubra sp. nov.

The gelatinous, calciferous red alga Renouxia antillana was described in 1995 based on material from Guadeloupe, French West Indies, and accommodated in a new family and order (Rhodogorgonaceae, Rhodogorgonales) along with the genus Rhodogorgon from Belize and Caribbean Panama. For more than 20 years, Renouxia has remained monotypic, with rare reports in the Caribbean and the Indo-Pacific (from Reunion Island to French Polynesia). DNA-based analyses of recently collected Renouxia specimens from Egypt showed that they are not conspecific with the Caribbean R. antillana and are described as R. marerubra sp. nov. Uncorrected p-distances between the Red Sea specimens and the generitype were 8.0% for COI, 6.5-7.3% for rbcL and 3.1% for UPA. Morphological and anatomical features are also presented for the newly described species and compared to its congener, with the first documented report of monoecism in the Rhodogorgonales. Besides the new record of Renouxia from the Red Sea, the geographic distribution of the genus is here extended with additional records from Sri Lanka, Indonesia, as well as the islands of Guam and Kosrae in the Western Pacific. The UPA phylogeny suggests that these new distribution records may also represent undescribed species, with representatives in two distinct genetic groups.