Cleaning up the grasses dustbin: systematics of the Arundinoideae subfamily (Poaceae)

Abstract

Among the 12 subfamilies currently considered in the systematics of Poaceae, the Arundinoideae have long been considered as a dustbin group, with a diversity of forms putatively hiding incertae sedis. Because this subfamily has been poorly investigated using molecular markers for the last two decades, the present study provides the first complete phylogeny of the Arundinoideae based on five plastid DNA loci sequenced for 12 genera, and analysed with and without plastome data from previous studies. The refined Arundinoideae appear to be a robust evolutionary lineage of Poaceae, divided into three tribes with some biogeographical patterns: (1) tribe Arundineae, the most heterogeneous tribe, including Eurasian Arundo, Australian Amphipogon and Monachather, and South African Dregeochloa; (2) tribe Crinipedeae (described here), including Crinipes, Elytrophorus, Styppeiochloa and Pratochloa (described here), with a South and East African distribution; and (3) tribe Molinieae, including Hakonechloa, Molinia and Phragmites, with a Eurasian distribution. Despite reduction in size, this small subfamily conserves a high diversity of morphological forms, with several small but highly differentiated genera. Finally, the molecular dating approach provides an evolutionary framework to understand the diversification of Arundinoideae, refuting Gondwanan vicariance between genera and suggesting capability for long distance dispersal.

Grasses through space and time: An overview of the biogeographical and macroevolutionary history of Poaceae

“…Tribe Molinieae Jirásek has a mean stem and crown age of 40.93 and 7.08 Ma. This crown age is younger than the 15 Ma age found in Hardion et al (2017), but that study noted a similarly long stem for this group and argued for a possible East Asian origin of its three or four genera. In our biogeographical analysis, the stem area is Afrotropical (50%), and the probable crown area is Cosmopolitan (68%).…”

“…and Crinipes Hochst. (four species) (Teisher et al, 2017; Hardion et al, 2017). Hardion et al (2021) found close relationships to Crinipes for two potentially extinct monotypic genera, Leptagrostis C.E.Hubb.…”

“…) and Crinipes Hochst. (four species) (Teisher et al, 2017;Hardion et al, 2017). Hardion et al (2021) 2017), but that study noted a similarly long stem for this group and argued for a possible East Asian origin of its three or four genera.…”

A worldwide phylogenetic classification of the Poaceae (Gramineae) III: An update

“…Since our 2017 classification, we have added two tribes, 22 new or resurrected subtribes, and rearranged the basal split in the PACMAD clade. Tribe Crinipedeae (Hardion et al, 2017) is accepted here (previously it was treated as subtribe Crinipinae in Molinieae) since Leptagrostis C. E. Hubb. and Piptophyllum C. E.…”

A worldwide phylogenetic classification of the Poaceae (Gramineae) II: An update and a comparison of two 2015 classifications

“…Kellogg () accepted 18 genera plus “ Eragrostis walteri Pilg.” [= Pratochloa walteri (Pilg.) Hardion] without subtribe affiliation (Hardion et al, in press). Soreng et al (2015b) placed Alloeochaete, Danthonidium , and Phaenanthoecium in the Danthonioideae but also included Moliniopsis in the Arundineae and reported that “ Eragrostis walteri ” belonged in the Arundinoideae.…”