Taxonomic revision of Muhlenbergia (Poaceae, Chloridoideae, Cynodonteae, Muhlenbergiinae) in Central America: phylogeny and classification Author Peterson, Paul M. https://orcid.org/0000-0001-9405-5528 Department of Botany MRC- 166, National Museum of Natural History, Smithsonian Institution, Washington, DC 20013 - 7012, USA peterson@si.edu Author Herrera Arrieta, Yolanda https://orcid.org/0000-0003-3814-6518 Instituto Politecnico Nacional, CIIDIR Unidad-Durango-COFAA, Durango, C. P. 34220, Mexico Author Lobo Cabezas, Silvia https://orcid.org/0009-0007-8100-2559 Herbario Nacional, Museo Nacional de Costa Rica, Apartado Postal 749 - 1000, San Jose, Costa Rica Author Romaschenko, Konstantin https://orcid.org/0000-0002-7248-4193 Department of Botany MRC- 166, National Museum of Natural History, Smithsonian Institution, Washington, DC 20013 - 7012, USA text PhytoKeys 2023 2023-08-03 230 1 106 http://dx.doi.org/10.3897/phytokeys.230.103882 journal article http://dx.doi.org/10.3897/phytokeys.230.103882 1314-2003-230-1 365B97AE96F45DB295043BF02F4AF4BE 9. Muhlenbergia flabellata Mez, Repert. Spec. Nov. Regni Veg. 17: 213. 1921. Fig. 9A-E Type . Costa Rica , San Jose , Cerro de Buena Vista , 3000m , 19 Jan 1891 , H. Pittier 3372 ( lectotype , designated here : G-00192109 [image!]; isolectotypes G-00192054 [image!], US-577110!) . Description. Caespitose and sprawling perennials . Culms 25-45 cm long, densely branched near base, decumbent and rooting below; internodes glabrous. Leaf sheaths much overlapping, flabellately arranged, glabrous, margins membranous, old sheaths flattened and papery; ligules (2.5-)3-8 mm long, membranous, hyaline, margins entire, decurrent, apex acute; blades 2-5 cm long, 1-2 mm wide, flattened to folded or involute, mainly basal, strongly ridged above with short stiff hairs, scabrous below. Panicles 3-9(-15) cm long, 2-3 cm wide, few-flowered, narrow, short-exserted, dark green; primary branches mostly 1-2 cm long, sometimes purplish with loosely appressed and ascending branches, spreading up to 30° from the culm axis, central axis slightly flattened, 2-ribbed, scabrous; pedicels 0.2-1 mm long, scabrous. Spikelets 3-4 mm long, erect, plumbeous to dark olivaceous; glumes 1.2-2 mm long, subequal, scabrid, apex obtuse to truncate, unawned; lower glumes 1.2-1.6 mm long, ovate, usually 1-veined, sometimes unveined; upper glumes 1.6-2 mm long, half as long as the lemma, oblong-obovate, usually 3-veined, but sometimes very faint, 2 or 3-toothed, the teeth 0.3-0.6 mm long, about 1/3 the length of the glume; lemmas 3-4 mm long, lanceolate, pilose below and along margins, the hairs mostly less than 1 mm long, the callus hairy, apex awned, the awns 4-8 mm long, flexuous, scabrous, olive-green, arising from a bifid apex, the teeth up to 0.5 mm long; paleas 3-4 mm long, as long as the lemma, olive-green, scabrous; anthers 1.8-2.1 mm long, fusiform, purple. Figure 9. A-E Muhlenbergia flabellata Mez. A habit B ligule C glumes D floret E floret F-J Muhlenbergia montana (Nutt.) Hitchc F habit G inflorescence H glumes I upper glume J florets. A, B, D, E drawn from W.C. Burger & L. Gomez P. 8309 (US-2695054) C drawn from G. Davidse 24971 (US-3014559) F-J drawn from A.S. Hitchcock 3143 (US-995116). Distribution. The species is endemic to Costa Rica and Panama ( Peterson et al. 2001 ). Ecology. Muhlenbergia flabellata occurs in paramos between 3100-3500 m often associated with Chusquea subtessellata Hitchc., Hypericum , ssp., Comaristaphylos arbutoides Lindl., Garrya laurifolia Hartw. ex Benth., and Buddleja nitida Benth. Comments. Muhlenbergia flabellata is a member of M. subg. Clomena and within this clade it is sister to M. quadridentata , a species primarily restricted to higher elevations that is common in Mexico and extends into Guatemala ( Peterson et al. 2021 ). Muhlenbergia flabellata can be separated from M. quadridentata in having short leaf blades 2-5 cm long (5-15 cm long in M. quadridentata ), short upper glumes 1.6-2 mm long [versus (3-)3.2-4 mm long in M. quadridentata ], and paleas scabrous throughout (versus pilose on the proximal 1/2 in M. quadridentata ) [ Peterson et al. 2007b ; Herrera Arrieta and Peterson 2018]. Specimens examined. Costa Rica. Cartago : Paraiso , Cerro de la Muerte , Cordillera de Salamanca , near summit of Cerro Satira , S. Horn 35 (CR); Paraiso , Cerro de la Muerte, M. Kappelle et al. 2377 (CR). Perez Zeledon : R. F. Los Santos , Cerro Bubis, A. Estrada et al. 2769 (CR); P. N. Chirripo , parte superior (norte) del Valle de los Conejos, J. Gomez 5339 (CR); R.F. Los Santos Alrededores de las torres de TV, cerro Buenavista, L. Gomez 6354 (CR); P. N. Chirripo , alrededores de refugio, parte inferior del valle de los Conejos, J. Gomez-L . 4503 (USJ); P. N. Chirripo , Cordillera de Salamanca , S facing slope of the Valle de los Conejos , about 1 km S of Cerro Nuevo , S. Horn 59 (CR); P.N. Chirripo , Valle de los Conejos, R. Ocampo 1466 (CR); P.N. Chirripo , Valle de los Conejos, R. Ocampo 1489 (CR); Rivas, A. Rodriguez 6422 (INB); Perez Zeledon , Rivas, A. Rodriguez 6541 (INB); P.N. Chirripo , refugio Los Crestones, G. Vargas et al. 340 (USJ); disturbed paramo, Cerro de la Muerte, R. Chazdon 447 (CR); Cordillera de Talamanca , Cerro de la Muerte , summit of Cerro Buvis, R.W. Pohl & G. Davidse 11621 (US); Direct line from Hotel La Georgina to Cerro Frio of the Cerro Buenavista complex ( Cerro de la Muerte ), area with television and radio towers, G. Davidse 24971 ( US , MO); Open paramo formation with stands of Chusquea bamboo 1-2.5 m tall and areas of short-burned forest and original forest 5-15 m tall in protected sites, along the trail to the Valle de los Leones and the lower part of theValle de los Conejos along the upper Rio Talari, W. Burger & L.D. Gomez 8309 (US). San Jose : W.C. Burger & R. Liesner 7467 (MO); Chirripo , G. Davidse & R. W. Pohl 1541 (MO); Buenavista, A. Jimenez 2666 (MO); Parque Nacional Chirripo , Paramo near Albergues de los Crestones, along Rio Talari near trail to Valle de los Conejos, J. G . Pruski et al. 3904 (MO); Buenavista, A. Weston 5846 (MO); Cerro Buenavista, P.M. Peterson, S. Lobo, J. Sanchez & R. Chacon 22855 (CR, US ); P. N. Chirripo Open paramo formation with stands of Chuquea bamboo 1-2.5 m tall on slopes and in the valley, short grasses and very short ( 30 cm )shrubs on the exposed ridges, Valle de los Conejos (upper rio ) Talari and trails to Cerro Chirripo and the Valle de Los Lagos , W.C. Burger & R. Liesner 7353 (CR); P. N. Chirripo , A. Chaverri et al. 1026 (CR); P. N. Chirripo Valle de los Conejos, A. Chaverri et al. 1172 (CR) , Panama . Bocas del Toro : Fabrega , A . Weston 10190 (MO) .