No abstract

Genera and species of the tribes Rhipileae and Rhipiliopsideae are abundant in most coral reef ecosystems worldwide. However, the group has been largely overlooked, and very little genetic data is available to accurately assess its diversity, phylogenetic relationships, and geographic distribution. Our study provided an in‐depth reassessment of tribes Rhipileae and Rhipiliopsideae based on a species‐rich dataset and the combination of molecular species delimitation, multilocus phylogenetic analyses (tufA, rbcL, and 18S rDNA), and morpho‐anatomic observations. Our results revealed an unexpected diversity of 38 morphologically validated species hypotheses, including 20 new species, two of which are described in this paper and one resurrected species (Rhipilia diaphana). Based on our phylogenetic results we proposed to redefine the genera Rhipilia and Rhipiliopsis and described two new genera, Kraftalia gen. nov. (Rhipileae) and Rhipiliospina gen. nov. (Rhipiliopsideae). Finally, we validated Rhipiliella Kraft and included it in the tribe Rhipileae. Although Rhipilia and Rhipiliopsis have a pantropical distribution, none of the species studied here appeared cosmopolitan; instead, they have restricted distributions.

Udoteaceae is a morphologically diverse family of the order Bryopsidales. Despite being very widespread geographically, this family is little known compared to the closely related Halimedaceae or Caulerpaceae. Using the most extensive Udoteaceae collection to date and a multilocus genetic dataset (tufA, rbcL and 18S rDNA), we reassessed the species diversity of the family, as well as the phylogenetic relationships, the diagnostic morpho-anatomical characters and evolutionary history of its genera, toward a proposed taxonomic revision. Our approach included a combination of molecular and morphological criteria, including species delimitation methods, phylogenetic reconstruction and mapping of trait evolution. We successfully delimited 62 species hypotheses, of which 29 were assigned (existing) species names and 13 represent putative new species. Our results also led us to revise the genera Udotea s.s., Rhipidosiphon s.s. and Chlorodesmis s.s., to validate the genus Rhipidodesmis and to propose three new genera: Glaukea gen. nov., Ventalia gen. nov., and Udoteopsis gen. nov. We also identified two large species complexes, which we refer to as the "Penicillus-Rhipidosiphon-Rhipocephalus-Udotea complex" and the "Poropsis-Penicillus-Rhipidodesmis complex". Using a time-calibrated phylogeny, we estimated the origin of the family Udoteaceae at Late Triassic (ca 216 Ma), whereas most of the genera originated during Paleogene.Our morphological inference results indicated that the thallus of the Udoteaceae ancestor was likely entirely corticated and calcified, composed of a creeping axis with a multisiphonous stipe and a pluristromatic flabellate frond. The frond shape, cortication and calcification are still symplesiomorphies for most extant Udoteaceae genera and represent useful diagnostic characters.