Combining the small South American genus Androtrichum into Cyperus (Cyperaceae)

Abstract

Background and aims – Molecular phylogenetic studies have provided a clearer understanding of the complex relationships within the family Cyperaceae. These studies have consistently shown that 12 allied genera are nested in the genus Cyperus. However, early Sanger sequencing-based phylogenies that included the two species of the small South American genus Androtrichum were inconclusive in placing this genus either as sister to Cyperus or as part of its early divergent lineages. A recent phylogenetic analysis however conclusively placed the two species of Androtrichum within the C3 Cyperus Grade. In this study, we investigate if the morphology and anatomy of Androtrichum species provide additional evidence for their placement in the genus Cyperus. In addition, we provide descriptions and distribution data for the species.Material and methods – Herbarium material from FLOR, FURB, GENT, ICN, and K has been studied. Samples of the culm and leaf were studied using histological methods. Taxonomic changes and typifications of names were performed according to the International Code of Nomenclature for algae, fungi, and plants. Key results – The morphology and the non-Kranz anatomy observed in the Androtrichum species confirm their placement among the other C3  Cyperus species. Androtrichum is combined into Cyperus. For one species, a combination in Cyperus is already available: Cyperus trigynus. For the other species, a new name in Cyperus is published: Cyperus byssaceus. Two typifications are established and morphological descriptions and distribution data are provided. Conclusion – By integrating recent molecular phylogenetic data with additional evidence from morphology and anatomy, Androtrichum is combined into Cyperus. As a result of this taxonomic change, a single monophyletic genus Cyperus is now recognised in the Cyperus Clade of tribe Cypereae.

Keywords

• anatomy
• Cypereae
• new name
• taxonomy