DOI: 10.1002/tax.70252 ISSN: 0040-0262
Molecular phylogeny, biogeography, and taxonomy of Afro‐alpine
Poa
species of sub‐Saharan Africa and Madagascar
Lynn J. Gillespie, Paul M. Peterson, Steven P. Sylvester, Roger D. Bull, Robert J. Soreng Abstract
We conducted phylogenetic analyses of
Poa
focused on Afro‐alpine species from sub‐Saharan Africa and Madagascar. We analyzed three plastid regions (
matK
,
trnC‐rpoB
,
trnT‐trnL‐trnF
) and two nuclear ribosomal (nr) regions (ITS, ETS) for 194 samples and 117 species of
Poa
. We present new DNA data for 93 samples, including 33 samples of seven Afro‐alpine species from Tanzania, Madagascar, and the Drakensberg. All previously detected major clades of
Poa
were strongly supported in the new trees, along with a novel, isolated, nrDNA clade (here termed the “
f
‐clade”) including six of seven Afro‐alpine species. Plastid sequences of all Afro‐alpine taxa resolved in
P
. subg.
Poa
supersect.
Homalopoa
(
H‐
clade), but only
P. leptoclada
was placed here based on nrDNA sequences. The novel Afro‐alpine nrDNA
f
‐clade aligned as sister to
Poa
sect.
Alpinae
and sect.
Arenariae
(
A
‐clade). We explore plausible hypotheses for the genetic origin of the new clade and biogeographical origins of Afro‐alpine species within
Poa
. The
f
‐clade is hypothesized to have a singular origin; however, with our current data the
H
‐clade was insufficiently resolved to identify with certainty the origin of the Afro‐alpine
f
‐clade. We provide evidence that the three endemic Madagascar species originated from two or three dispersal events from mainland Africa. Taxonomy of native Afro‐alpine species includes synonymy, morphological descriptions, distributions, notes on breeding systems and spikelet pubescence variations. We describe one new sky‐island species (
P. fernandopoensis
) from Equatorial Guinea and make 10 lectotypifications (
P. ankaratrensis
,
P. annua
var
. hypsophila
,
P. friesiorum
,
P. heterogama
,
P. leptoclada
,
P. madecassa
,
P. perlaxa
,
P. perrieri
,
P. pumilio
,
P. ruwenzoriensis
). We provide a key to all
Poa
taxa of sub‐Saharan Africa and Madagascar including introduced species and a compilation of all known chromosome numbers of African taxa (with some corrections), including five new chromosome counts for
P. binata
. We also provide a new combination,
P. anatolica
, for the single species of
Oreopoa.