Phylogeny of Muhlenbergia subg. Pseudosporobolus, including M. spatha (Poaceae, Chloridoideae, Cynodonteae, Muhlenbergiinae) now found in Zacatecas, Mexico

Paul M Peterson,Konstantin Romaschenko,Yolanda Herrera Arrieta

doi:10.3897/phytokeys.103.26162

Abstract

Muhlenbergia spatha, previously known only from near the type locality in San Luis Potosí, is reported from two localities in Zacatecas, Mexico. Historically, botanists have overlooked this diminutive annual. To clarify affinities of M. spatha, we present a molecular phylogeny emphasising species in M. subg. Pseudosporobolus using sequence data from two plastid markers (rpl32-trnL and rps16 intron) and nrDNA ITS. In addition, we include an updated description, illustration and discussion of the habitat of M. spatha.

Highlights

Muhlenbergia spatha Columbus is a small annual first collected in the mountains of San Miguelito, in the valley of San Luis Potosí by J.G
Muhlenbergia spatha can be separated from other species in the genus by its possessing small, few-branched condensed panicles that are partially included in a spatheolate sheath with each branch containing 1–5 sessile spikelets
Beauv = Muhlenbergia Schreb.), but he suggested the inflorescences were nearer to members of the Andropogoneae or Pappophoreae

Summary

Introduction

Muhlenbergia spatha Columbus is a small (usually less than 20 cm tall) annual first collected in the mountains of San Miguelito, in the valley of San Luis Potosí by J.G. The Cynodonteae includes 25 subtribes, 95 genera and 859 species (Peterson et al 2010a, 2016, 2017; Soreng et al 2017). Molecular DNA sequence studies support placement of Schaffnerella in the Cynodonteae, aligning the genus within the monogeneric subtribe Muhlenbergiinae Pilg. We report two new collections of Muhlenbergia spatha in Zacatecas, include a complete updated description and illustration and present a molecular phylogeny of species in M. subg. Pseudosporobolus was included to characterise evolutionary relationships of M. spatha, since earlier analyses for this species were based on few markers (Columbus et al 2010; Peterson et al 2010b). Based on a single sequence (rpl32-trnL), M. spatha paired with M. alopecuroides (Griseb.) P.M. Peterson & Columbus in a plastid tree and it paired with M. wrightii Vasey ex J.M. Coult.

Materials and methods

Results and discussion

Muhlenbergia arenicola Buckley