Muhlenbergia breviligula Hitchc., N. Amer. Flora 17(6):458. 1935.

Peterson, Paul M., Herrera Arrieta, Yolanda, Lobo Cabezas, Silvia & Romaschenko, Konstantin, 2023, Taxonomic revision of Muhlenbergia (Poaceae, Chloridoideae, Cynodonteae, Muhlenbergiinae) in Central America: phylogeny and classification, PhytoKeys 230, pp. 1-106 : 1

2. Muhlenbergia breviligula Hitchc., N. Amer. Flora 17(6):458. 1935.

Fig. 3A-E

Type.

Guatemala, Guatemala City, collected on clay hill, 1500 m, 2 Dec 1911, A.S. Hitchcock 9063 (holotype: US-995888!) .

Description.

Densely caespitose perennials. Culms 70-140 tall, erect, stout, compressed-keeled near base, puberulent to glabrous below the nodes; internodes glabrous. Leaf sheaths 8-26 cm long, mostly longer than the lower internode, scaberulous to glabrous, basally becoming brown, curled and fibrillose or shredded, margins entire, apex pubescent on abaxial surface; ligules 0.1-2 mm long on the culm leaves, of innovations 6-13 mm long, membranous to chartaceous with a rim of hairs, lacerate, apex truncate; sheath auricles 1.5-6 mm long, whitish when present, often lacking; blades 20-50 cm long, 2-3 mm wide, usually abruptly narrowed at base (sheath and blade junction), flat to folded, scabrous above, sometimes pubescent near throat and scaberulous below. Panicles 30-51 cm long, 3-10 cm wide, nodding, somewhat dense, yellowish to purplish brown or purplish green; primary branches mostly 3-12 cm long, ascending, lax and nodding, appressed to spreading up to 40° from the culm axis; pedicels 0.5-3 mm long, scaberulous. Spikelets 2-3.5 mm long, erect, yellowish to purplish-brown; glumes 2-3.5 mm long, equal or a little longer than the floret, equal in length, lanceolate to oblong-lanceolate, 1-veined, occasionally the upper 2-veined, apex acute to acuminate, often scaberulous, sometimes mucronate, the mucros up to 0.2 mm long; l emmas 2.1-2.8 mm long, lanceolate to oblong-lanceolate, awned, midvein and margins pubescent to sparsely pilose on the proximal 2/3, the hairs up to 0.3 mm long, apex acute to acuminate; awns 6-18 mm long, straight or flexuous, borne just below the apex; callus sparsely pilose; paleas 2-2.7 mm long, oblong, the proximal 2/3 pubescent to sparsely pilose between the veins, apex acute; anthers 1-1.7 mm long, purple or yellow. Caryopses 1-1.3 mm long, fusiform, light brownish.

Phenology.

Flowering October through December.

Distribution.

Chiapas, México, southeast to Guatemala, Honduras, El Salvador, and Nicaragua ( Peterson et al. 2001; Menjívar Cruz et al. 2021).

Ecology.

Muhlenbergia breviligula occurs on rocky slopes, along drainages, and in open pine-oak woodlands; 650-2530 m.

Comments.

This species is morphologically similar to M. emersleyi Vasey, a species common in southwestern USA and northern México. However, M. breviligula differs in having culms with a short ligule 0.2-2 mm long (ligules 10-25 mm long in M. emersleyi ), leaf blades 2-3 mm wide (2-6 mm wide in M. emersleyi ), and persistent fimbrillose basal sheaths (not as persistent in M. emersleyi ) [ Soderstrom 1967; Peterson 2003]. Muhlenbergia breviligula , a member of M. subg. Trichochloa , has been found in an unsupported clade with three other species, distributed in North America ( México), Central America, and South America (Columbia, Ecuador, and Peru) [ M. lehmanniana , M. versicolor , and M. maxima Lægaard & Sanchez Vega] (Fig. 1A ; Peterson et al. 2021).

Specimens examined.

El Salvador. Chalatenango: San Fernando, creciendo a orilla de la calle, J. González 398 (MO). Honduras. Choluteca: San Marcos de Colón, pine forest area near San Marcos [de Colón], L.O. Williams & A. Molina R. 10921 (MO). El Paraíso: Guinope, Galeras, along road ca 10 km S of El Zamorano, open pine forest. [Originally reported from Francisco Morazán], R.W. Pohl 12527 (MO); Alauca, Las Manos , 5 km N of Las Manos, near Los Limones, R.W. Pohl & M. Gabel 13430 (MO). Francisco Morazán: Tatumbla, 24 km E de Tegucigalpa, bosque húmedo subtropical, I. Cruz P. 75 (MO); In mountains along highway, 30 km W of Tegucigalpa, W.A. Archer 3846 (US); Drainage of the Rio Yaguare , floresta de pino roble, acueducto de la EAP, Zamorano, A. Molina R. 1593 (US); foothills of Mt. Uyuca , beyond Las Floras, overhanging steep bank in pine forest, J.R. Swallen 11323 (US); San Antonio de Oriente , El Zamorano , R.W. Pohl 12509 (MO); San Antonio del Oriente , overhanging bank, small shady canyon, about 2 km above San Antonio, J.R. Swallen 10968 (US); Distrito Central, El Picacho, carretera en el Picacho, Villatoro et al. 137 (MO). Lempira: Gracias, Rio Mejocote [Rio Grande de Mejocote], 9 km de Gracias, pinares, C. Nelson et al. 252 (MO). Ocotepeque: Santa Fe, about 8 km southwest of Santa Fe , near the Guatemala border, R.A. Molina et al. 31271 (MO). Olancho: Jutiapa, mountain above a fire tower, Jutiapa Forest Station , between Concordia and Salamáa, pine forest on a steep slope, R.W. Pohl & M. Gabel 13493 (MO). Santa Bárbara: Quimistán, Cofradia , ca. 8 km S of Cofradia, along Highway 18, open pine savana on a hill, R.W. Pohl & M. Gabel 13392 (MO). El Paraíso: Dry hillsides along the Quebrada de Dantas , Rio Choluteca Valley about 16 km north of Yuscaran , L.O. Williams & R.P. Williams 18652 (US). Guatemala. Chiquimula: along Rio Taco , between Chiquimula and Montana Barriol, 3-15 mi NW of Chiquimula, J.A. Steyermark 30649 (US). Alta Verapaz: vicinity of Secanquim, O.F. Cook & C.B. Doyle 60 (US). Guatemala: Guatemala City, A S. Hitchcock 9063 (MO), A.S. Hitchcock 9064 (US). A.S. Hitchcock 9109 (US). Huehuetenango: Mountains wet of Aguacatan, on the road to Huehuetenango, open bank, P.C. Standley 81190 (US). Zacapa: 13 km east of El Lobo , North-facing slope of open field and thickets, Quercus and Pinus on drier slopes, W.E. Harmon & J.A. Fuentes 1851 (MO). Mexico. Chiapas: Arriaga: At La Mina Microwave Station , D.E. Breedlove 56328 (CAS, MO); Chiapa de Corso : Above El Chorreadero, D.E. Breedlove & R.F. Thorne 20499 (CAS, MO); 30 miles W of San Cristobal de las Casas on Mex 190 J. N. Brunken & C. H. Perino 354 (MEXU); Cintalapa: Crest of the Sierra, near the microwave station of La Mina, 12 km S of Mexican Highway 190, near Rizo de Oro , D.E. Breedlove & R.F. Thorne 20555 (CAS, MO); Comitan de Dominguez : 6 km N of Comitán along Mexican Highway 190, D.E. Breedlove & G. Davidse 54872 (CAS, MO); 6 km N of Comitán along Mexican Highway 190, D.E. Breedlove & G. Davidse 54870 (CAS, MO); Huistán: 10 km E of Huistán. [Tenejapa Mpo. (Huistan), D.E. Breedlove & G. Davidse 55186 (CAS, MO); Comitán de Domínguez: 6 km N of Comitán along Mexican Highway 190, D.E. Breedlove & G. Davidse 54872 (CAS, MO); 6 km N of Comitán along Mexican Highway 190, D.E. Breedlove & G. Davidse 54870 (CAS, MO); Ixtapa: near the Zinacantán Paraje of Muctajoc. Slope with tropical deciduous forest, D.E. Breedlove & G. Davidse 54005 (MEXU, CAS, MO), 54006 (CAS, MO), 54008 (MEXU, CAS, MO), 54009 (MEXU, CAS, MO), 54011 (CAS, MO); Intersection of the Tuxtla Gutiérrez-San Cristobal de las Casas and the Villahermosa highways, G. Davidse et al. 30101 (MO); along road from Zinacantán center to Ixtapa near Paraje Vo Bits, D.E. Breedlove 40709 (CAS, MO); Jiquipilas: Ejido Tierra y Libertad, A. Reyes-García 5556 (MEXU); La Independencia: 6-10 km NNE of La Soledad along logging road from Las Margaritas to Campo Alegre, D.E. Breedlove & B.M. Bartholomew 55670 (CAS, MO); La Trinitaria: a 12 km al S de la Trinitaria, camino a Cd. Cuauhtemoc, E.M. Martínez S. & W.D. Stevens 23905a (MEXU); 6-7 km S of La Trinitaria, G. Davidse et al. 29938 (MO); 6 km south of La Trinitaria on Mexican Highway 190, D.E. Breedlove & G. Davidse 55074 (CAS, MO); 20 km south of La Trinitaria, D.E. Breedlove & G. Davidse 55067 (CAS, MO); D.E. Breedlove 4216 (CAS, MO); Oxchuc: 5 km east of Oxchuc, D.E. Breedlove & F. Almeda 57120 (CAS, MO); San Cristóbal las Casas: NE edge of San Cristóbal las Casas, D.E. Breedlove 54721 & G. Davidse (CAS, MEXU, MO); Northeast edge of San Cristóbal Las Casas, D.E. Breedlove & G. Davidse 54746 (CAS, MEXU, MO); San Fernando: Parque Nacional del Sumidero, 20-22 km NW of Tuxtla Gutiérrez, along the road to the canyon Outlook, G. Davidse et al. 29764 (MO); Northeast edge of San Cristóbal Las Casas, D.E. Breedlove & G. Davidse 54728 (CAS, MO); San Juan Chamula, C. Santíz Ruíz 222 (MEXU); Tuxtla Gutiérrez: 22 km north of Tuxtla Gutiérrez. Cliff faces and limestone bluffs with Seasonal Evergreen Forest, Calycophyllum, Zanthoxylum, Bursera, Quercus , Ficus and Erythrina at El Sumidero, D.E. Breedlove & B.M. Bartholomew 55482 (CAS, MO); 16 km north of Tuxtla Gutiérrez on road to El Sumidero, D.E. Breedlove & Bruce M. 55494 (CAS, MO); t El Sumidero, 22 km north of Tuxtla Gutiérrez, D.E. Breedlove & A.R. Smith 21557 (CAS, MO); Venustiano Carranza: Wooded slope near the town, along the road to Pugiltic, R. M. Laughlin 2702 (ENCB); 3 mi S of Aguacatenango along road to Pinola Las Rosas, D.E. Breedlove & P.H. Raven 13135 (ENCB); Villa Corzo: Above Colonia Vincente Guerrero on road to Finca Cuxtepec [Custepec], D.E. Breedlove 54599 & G. Davidse (CAS, MO); near Paraje Navenchauk, D.E. Breedlove & G. Davidse 53899 (CAS MO); Near Colonia Vincente Guerrero, D.E. Breedlove 48584 (CAS, MO); Zinacantán: near Paraje Zinacantán, D.E. Breedlove 53901 & G. Davidse (MEXU); near the Zinacantán Paraje of Muctajoc, D.E. Breedlove & G. Davidse, (MEXU); D.E. Breedlove 13807 (DS, MO). Nicaragua. Nueva Segovia: Santa María, km 242, 1 km al W de Santa María, P.P. Moreno 25214 (MO).

Figures

Figure 1. A, B Bayesian tree inferred from combined plastid (ndhA intron, rps 16 - trnK, rps 16 intron, rps 3, and rpl 32 - trnL) and ITS sequences. Thick branches indicate posterior probabilities of 0.95 - 1; species in bold occur in Central America; Scale bar: 2 %.

Figure 3. A-E Muhlenbergia breviligula Hitchc. A habit B ligule with auricles C glumes D floret E stamens and lodicules F-J Muhlenbergia nigra Hitchc. F habit G ligule H glumes I floret J stamens, pistil, and lodicules. A-E drawn from A. Molina R. 25227 (US- 2942492) F-J drawn from S. D. Koch 76255 (US- 2824590).