Revision of Poa L. (Poaceae, Pooideae, Poeae, Poinae) in Mexico: new records, re-evaluation of P. ruprechtii, and two new species, P. palmeri and P. wendtii

A revision and key to the 23 species and eight subspecies of Poa (including Dissanthelium) known to occur in Mexico is provided. All voucher specimens seen are cited for accepted taxa, except P. annua for which one voucher per state is provided. Taxa not previously known from, or poorly understood in, Mexico are discussed. Poa palmeri sp. nov. is endemic to forested slopes of the Sierra Madre Oriental, and we distinguished it from P. ruprechtii s.s., a species of central Mexico that is here emended to include P. sharpii (syn. nov.). Poa wendtii sp. nov. is described from the Sierra Santa Rosa in northern Coahuila. Poa tacanae is placed in synonymy in P. seleri. Poa gymnantha and P. occidentalis are newly reported for Mexico, and material historically identified as P. villaroelii are placed in P. chamaeclinos. The genus Dissanthelium is considered to belong within Poa, and the Mexican taxa, D. calycina subsp. mathewsii and D. californicum, are treated as P. calycina var. mathewsii and P. thomasii, respectively. Poa subsect. Papillopoa subsect. nov. is erected for P. mulleri. Lectotypes are designated for P. conglomerata and P. seleri.