Advances in the phylogeny of the South American cool-season grass genus Chascolytrum (Poaceae, Pooideae): a new infrageneric classification

Abstract

Chascolytrum, as currently circumscribed, includes 22–23 South American species that were previously included in nine different genera (Chascolytrum, Briza, Poidium, Calotheca, Microbriza, Gymnachne, Rhombolytrum, Lombardochloa and Erianthecium). Due to the remarkable morphological diversity, the relationships in Chascolytrum s.l. have remained poorly understood, and no infrageneric classification could be proposed based on the latest molecular phylogenetic studies. In this study, we combined molecular (GBSSI, trnL-trnL-trnF and rps16 intron) and morphological characters to investigate the phylogenetic relationships in Chascolytrum s.l. Based on this, morphologically diagnosable clades were recognized as eight sections (Calotheca, Chascolytrum, Hildaea, Lombardochloa, Microbriza, Obovatae, Poidium and Tricholemma), of which three are new and three are monospecific. We describe each section and discuss the new infrageneric classification in comparison with the previous infrageneric classification proposed for the group under the genus Briza. A taxonomic key and images for most of the species in each section are provided. Last, the use of single-copy nuclear genes and morphological data for future phylogenetic reconstructions encompassing Chascolytrum is highlighted.

A comprehensive species sampling sheds light on the molecular phylogenetics of Calothecinae (Poaceae, Pooideae, Poeae): Evidence for a new subtribe and multiple genera within the Chascolytrum clade

“…was unresolved in the analyses of da Silva et al (2020a), whereas here it is sister to the remainder of clade B. Poidium, as accepted here, differs from generic circumscriptions proposed by Matthei (1975), Nicora & Rúgolo de Agrasar (1981), and Bayón (1998) and from the narrower circumscription of Chascolytrum sect. Poidium proposed by da Silva et al (2020a). Within Poidium , we include nine species and two varieties that da Silva et al (2020a) classified in C .…”

“…Poidium . The affinities of T. brasiliense with Chascolytrum species thus result in paraphyly of the latter genus as circumscribed by Essi et al (2017) and da Silva et al (2020a, 2020b). As the relationships among T. bulbosum and the two Chascolytrum clades are unresolved, it is unclear if T. bulbosum also contributes to paraphyly of Chascolytrum when circumscribed broadly.…”

“…Nicora & Rúgolo de Agrasar (1981) and Bayón (1998) divided the group into five genera ( Briza, Calotheca , Microbriza , Poidium , and Rhombolytrum ), some with different circumscriptions compared with Matthei′s (1975) treatment. Essi et al (2008) and da Silva et al (2020a) provided detailed summaries of these varying generic classifications.…”

Phylogenetic lineages and the role of hybridization as driving force of evolution in grass supertribe Poodae

“…Desv.) after inclusion of several segregate genera such as Erianthecium Parodi (type E. bulbosum Parodi), Rhombolytrum Link (type R. rhomboideum Link), Poidium Nees (P. uniolae (Nees) Matthei sampled) and others (Essi & al., 2017;Silva & al., 2020). Chascolytrum proved monophyletic in this study according to the nrDNA data (89/88/1.00; Fig.…”

“…Since then, due to the sheer size of the group, usually representative genera were selected for comparative studies to gain an overview on the whole Poodae and their major groupings using morphological data, plastid DNA restriction site analysis, traditional Sanger and, more recently, plastid genome sequencing (Soreng & Davis, ; Davis & Soreng, ; Döring & al., ; Quintanar & al., ; Soreng & al., ; Schneider & al., ; Saarela & al., , ; Pimentel & al., ; Orton & al., ). Other studies focused on special groups using an in‐depth sampling of taxa, for example, within traditional Aveneae (Grebenstein & al., ; Döring, ; Saarela & al., , ; Wölk & Röser, , ; Barberá & al., ) and Poeae (Schneider & al., ; Birch & al., , ), in which especially the subtribes Poinae (Hunter & al., ; Gillespie & Soreng, ; Gillespie & al., , , , , ; Refulio‐Rodríguez & al., ; Hoffmann & al., ; Soreng & al., , ; Nosov & al., , ), Loliinae (Torrecilla & Catalán, , Catalán & al., , ; Torrecilla & al., ; Inda & al., ; Cheng & al., ; Minaya & al., ), Sesleriinae (Kuzmanović & al., ), Brizinae and Calothecinae (Essi & al., ; Persson & Rydin, ; Silva & al., ) were studied.…”