Morphological and phylogenetic evidence for subtribe Cinninae and two new subtribes, Hookerochloinae and Dupontiinae (Poaceae tribe PoeaePPAMclade)

Abstract

Molecular phylogenetic analyses and morphological characters of the grass supersubtribe Poodinae (tribe Poeae, PPAM clade) were evaluated with the goal of determining the relationships of single-flowered spikelet genera recently classified in subtribe Cinninae and the sister genus of the New Zealand endemic genus Simplicia. A total of 136 samples representing 40 genera and 105 species were analyzed for three plastid (matK, trnC-rpoB, trnT-trnL-trnF) and two nuclear ribosomal DNA markers (ITS, ETS). The Cinninae subtribe, including Aniselytron, Cinna, Cinnastrum, Cyathopus, and Simplicia, was recovered as monophyletic with weak support only in the combined analysis with known/putative hybrid taxa removed. Cinna (excluding Cinnastrum) resolved as paraphyletic due to the position of the morphologically distinctive Cyathopus. Cinninae are characterized by flat leaf blades, open panicles, small, strongly compressed, single-flowered spikelets, with a rachilla extension, and lemmas that are awnless or with a short subterminal awn. The genus Cinnastrum is resurrected for Cinna poiformis and differs from Cinna in its broader glumes and subterete caryopsis with solid endosperm. Simplicia is likely most closely related to the southern and eastern Asian genus Aniselytron, with which it shares unequal and short lower glumes and spikelet disarticulation above the glumes, in contrast to the other three genera of the subtribe. The HSAQN clade, which has mainly multi-flowered spikelets and is sister to Cinninae, is named subtribe Hookerochloinae, including Arctagrostis, Hookerochloa, Nicoraepoa, Saxipoa, and Sylvipoa. The DAD clade, which is known to be of reticulate origin postulated here as involving Cinninae, is named subtribe Dupontiinae, and includes Arctohyalopoa, Arctophila, Dupontia, and Dupontiopsis. These three subtribes, together with subtribes Alopecurinae, Beckmanniinae, and Ventenatinae (along with Brizochloinae not tested here), make up the well-supported Alopecurinae superclade within supersubtribe Poodinae.

Biogeography, timing, and life‐history traits in the PPAM clade: Coleanthinae (syn. Puccinelliinae), Poinae, Alopecurinae superclade, Miliinae, and Avenulinae and Phleinae (Poaceae, Pooideae, Poeae)

“…Several PPAM taxa included in our analyses are known to be reticulate in origin or have extra nrDNA copies from introgression. Arctopoa is nested within Poa in this and other plastid analyses, but in nrDNA studies, it resolves within the Alopecurinae superclade, thus exposing its reticulate origin (e.g., Gillespie et al, 2008Gillespie et al, , 2009Gillespie et al, , 2010Gillespie et al, , 2022Soreng et al, 2015a;Tkach et al, 2020). The reticulate origin of the DAD clade of Soreng et al (2015a), now four genera (including Arctohyalopoa described in Tkach et al, 2020), all hexaploids, was postulated by Soreng et al (2015a) and discussed and named Dupontiinae by Gillespie et al (2022).…”

“…Tkach et al (2020), the previous study most complete at the generic level (all superclade Alopecurinae ("ABCV clade") genera sampled except Pseudophleum and the newly recognized Cinnastrum [Gillespie et al, 2022]), resolved only one of the superclade Alopecurinae subtribes, Ventenatinae, in their plastid analysis. Two of the subtribes, Cinninae and Hookerochloinae, did not resolve as monophyletic here in our plastid analyses for various reasons, including low sequence diversity and homoplasious states in these two subtribes, but they were resolved as sister clades using nrDNA combined with plastid data (Gillespie et al, 2022). Hookerochloinae was strongly supported ("HSAQN" clade) using ITS + ETS data (Gillespie et al, 2009(Gillespie et al, , 2022Soreng et al, 2015a;Tkach et al, 2020), or ITS alone (Hoffmann et al, 2013).…”

“…We will discuss relationships in more detail, including at the generic and species levels, and evidence for reticulation based on both plastid and nrDNA data in a future paper. Alopecurinae superclade subtribes Cinninae and Hookerochloinae were the focus of a recent study including concatenated plastid and nrDNA (ITS and ETS) data, where the subtribes were more resolved than presented here based on plastid only (Gillespie et al, 2022).…”

“…Since then, five other studies have investigated the phylogeny of PPAM in detail (Gillespie et al, 2009(Gillespie et al, , 2010(Gillespie et al, , 2022Soreng et al, 2015a;Tkach et al, 2020). The unplaced genera were subsequently recognized in clades and subtribes as sampling and sequencing expanded (Brizochloinae, Dupontiinae, Hookerochloinae, Ventenatinae) Tkach et al, 2020;Gillespie et al, 2022). Alopecurinae, in this broad sense, with Phleum removed, is called the Alopecurinae superclade (Gillespie et al, 2022, and here).…”

“…870 species (Table 1). One additional genus, Cinnastrum (Gillespie et al, 2022), and two new genera proposed by Tkach et al (2020) were recognized since the classification in .…”