A molecular phylogeny and new subgeneric classification of Sporobolus (Poaceae: Chloridoideae: Sporobolinae)

Abstract

The grass subtribe Sporobolinae contains six genera: Calamovilfa (5 spp. endemic to North America), Crypsis (10 spp. endemic to Asia and Africa), Psilolemma (1 sp. endemic to Africa), Spartina (17 spp. centered in North America), Sporobolus (186 spp. distributed worldwide), and Thellungia (1 sp. endemic to Australia). Most species in this subtribe have spikelets with a single floret, 1-veined (occasionally 3 or more) lemmas, a ciliate membrane or line of hairs for a ligule, and fruits with free pericarps (modified caryopses). Phylogenetic analyses were conducted on 177 species (281 samples), of which 145 species were in the Sporobolinae, using sequence data from four plastid regions (rpl32-trnL spacer, ndhA intron, rps16-trnK spacer, rps16 intron) and the nuclear ribosomal internal transcribed spacer regions (ITS) to infer evolutionary relationships and provide an evolutionary framework on which to revise the classification. The phylogenetic analysis provides weak to moderate support for a paraphyletic Sporobolus that includes Calamovilfa, Crypsis, Spartina, and Thellungia. In the combined plastid tree, Psilolemma jaegeri is sister to a trichotomy that includes an unsupported Urochondra-Zoysia clade (subtr. Zoysiinae), a strongly supported Sporobolus somalensis lineage, and a weakly supported Sporobolus s.l. lineage. In the ITS tree the Zoysiinae is sister to a highly supported Sporobolinae in which a Psilolemma jaegeri-Sporobolus somalensis clade is sister to the remaining species of Sporobolus s.l. Within Sporobolus s.l. the nuclear and plastid analyses identify the same 16 major clades of which 11 are strongly supported in the ITS tree and 12 are strongly supported in the combined plastid tree. The positions of three of these clades representing proposed sections Crypsis, Fimbriatae, and Triachyrum are discordant in the nuclear and plastid trees, indicating their origins may involve hybridization. Seven species fall outside the major clades in both trees, and the placement of ten species of Sporobolus are discordant in the nuclear and plastid trees. We propose incorporating Calamovilfa, Crypsis, Spartina, Thellungia, and Eragrostis megalosperma within Sporobolus, and make the requisite 35 new combinations or new names. The molecular results support the recognition of 11 sections and 11 subsections within Sporobolus s.l.; four sections are new:

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

“…Stapf], a suffrutescent perennial with stiff, hard, much-branched culms up to 2 m tall, lemmas 4-5 mm long, and is found along the immediate coast bordering the Red Sea in sand dunes or plains (Peterson et al, 2016). Molecular analyses of the three species formerly placed in Odyssea confirmed that each one had a different evolutionary origin (Peterson et al, 2014b(Peterson et al, , 2016. Odyssea paucinervis, as previously mentioned, is sister to Aeluropus, and both genera have elongated rhizomes, stiff and pungent leaf blades, synflorescences composed of racemes born on a central axis, multiple-flowered spikelets, and mucronate lemmas (Clayton et al, 2016).…”

Notulae to the Italian alien vascular flora: 2

“…The species comes from North America, ranging from southern Canada to central and eastern United States (coastal and inland prairies; see Barkworth 2003). Known as Spartina pectinata Bosc ex Link, it has to be ascribed to the genus Sporobolus (Peterson et al 2014a, Peterson et al 2014b, Applequist 2016. It is used and traded as a garden ornamental.…”

Grasses of Egypt

“…The list of species is primarily based on Cope's (2005) treatment of the Gramineae of Egypt. We have consulted many taxonomic treatments during the preparation of this work, most notable are: Bor (1968), Boulous (1995Boulous ( , 2005, Chaudhary (1989), Clayton et al (2006), Cope (1982Cope ( , 2005Cope ( , 2007, Forman and Perrson (1974), Scholz (1980, 1981), Ibrahim and Peterson (2014), Liu et al (2014), Peterson et al (2003;2010, 2011, 2014a2014b;2014c;2014d;, Phillips (1995), , Saarela et al (2014), Sherif and Siddiqi (1988), Täckholm (1956Täckholm ( , 1974, and Wickens (1977).…”