J Syst Evol

• Research Articles •    

Phylogeny and biogeography of Calamagrostis (Poaceae: Pooideae: Poeae: Agrostidinae), description of a new genus, Condilorachia (Calothecinae), and expansion of Greeneochloa and Pentapogon (Echinopogoninae)

Paul M. Peterson1*, Robert J. Soreng1, Konstantin Romaschenko1, Patricia Barberá2, Alejandro Quintanar3, Carlos Aedo4, and Jeffery M. Saarela5   

  1. 1Department of Botany, National Museum of Natural History, Smithsonian Institution, Washington DC 20013-7012, USA

    2Department of Africa and Madagascar, Missouri Botanical Garden, 4344 Shaw Blvd., St. Louis, MO 63110-2291, USA

    3Herbarium MA, Unidad de Herbarios, Real Jardín Botánico, Consejo Superior de Investigaciones Cientificas, 28014, Madrid, Spain

    4Department of Biodiversity and Conservation, Real Jardín Botánico, Consejo Superior de Investigaciones Cientificas, 28014, Madrid, Spain

    5Beaty Centre for Species Discovery and Botany Section, Research and Collections, Canadian Museum of Nature, Ottawa, Ontario KIP 6P4, Canada

  • Received:2021-07-31 Accepted:2021-12-09 Online:2021-12-11

Abstract: To investigate the evolutionary relationships and biogeographical history among the species of Calamagrostis and other members of subtribes Agrostidinae, Calothecinae, Echinopogoninae, and Paramochloinae, we generated a phylogeny based on DNA sequences from one nuclear ribosomal (ITS) and three plastid regions (rpl32-trnL spacer, rps16-trnK spacer, and rps16 intron). Based on our phylogeny, we identified seven species groups (clades) within Calamagrostis: the Meridionalis group comprises two species from Central and South America, the Americana group comprises species from North America, the Deyeuxia and Epigeios groups comprise species from Eurasia, the Orientalis group comprises species from East Asia, the Purpurea group comprises species from Eurasia and North America, and the Calamagrostis group comprises species from Eurasia and North America. We hypothesize that Calamagrostis originated in North America with the primary split of the Meridionalis group, followed by split between the autochthonous Americana group and two future Eurasian branches encompassing all the remaining groups, which possibly dispersed into Eurasia independently. The molecular data suggest that hybridization and genomic introgression played a prominent role in the evolutionary history of Calamagrostis. We propose a new genus, Condilorachia, segregated from Trisetum s.l., with three species from South America for which we propose new combinations: Condilorachia bulbosaCondilorachia brasiliensis, and Condilorachia juergensii; a new combination in Greeneochloa, Greeneochloa expansa; and the subsumption of Dichelachne into Pentapogon with 20 new combinations: Pentapogon avenoidesPentapogon brassiiPentapogon chaseianus, Pentapogon crinita, Pentapogon densus, Pentapogon frigidus, Pentapogon gunnianus, Pentapogon hirtella, Pentapogon inaequiglumis, Pentapogon lautumia, Pentapogon micrantha, Pentapogon parva, Pentapogon quadrisetus, Pentapogon rara, Pentapogon robusta, Pentapogon scaberulus, Pentapogon sclerophyllus, Pentapogon suizanensis, Pentapogon sieberiana, and Pentapogon validus. We provide a diagnosis, description, and a key to the species of Condilorachia.

Key words: Calamagrostis, Dichelachne, grasses, Greeneochloa, ITS, molecular systematics, Pentapogon, plastid sequences, Taxonomy