Muhlenbergia monandra Alegria & Rugolo , Darwiniana 39(1-2): 20, 22, f. 1-3.

Peterson, Paul M., Vega, Isidoro Sanchez, Romaschenko, Konstantin, Giraldo-Canas, Diego & Rodriguez, Nancy F. Refulio, 2018, Revision of Muhlenbergia (Poaceae, Chloridoideae, Cynodonteae, Muhlenbergiinae) in Peru: classification, phylogeny, and a new species, M. romaschenkoi, PhytoKeys 114, pp. 123-206 : 163-164

14. Muhlenbergia monandra Alegria & Rugolo, Darwiniana 39(1-2): 20, 22, f. 1-3. Fig. 10A-M

Type.

Peru, Depto. Lima, Prov. Canta, 5 km arriba de San José en camino a Huamantanga, frente a Apio, 2700 m, 21 May 1999, A. Granda Paucar & J.J. Alegría Olivera 2230 (holotype: MOL; isotypes: BRIT-23827 [image!], SI! [SI-016006 image!], TEX, US-3376226! [US-00901642 image!], USM-000747 [image!]).

Description.

Tufted annuals. Culms 4-25 cm tall, 0.3-0.7 mm in diameter near base, erect to decumbent, branching below, glabrous, 2 or 3 glabrous nodes, scaberulous below the nodes; internodes 0.5-9 cm long. Leaf sheaths 0.5-4.7 cm long, usually shorter than the internodes, compressed, mostly glabrous, scaberulous near the summit, margins scarious; ligules 1-3 mm long, hyaline, decurrent, apex truncate to obtuse, lacinate to irregularly dentate; blades (0.5-)1-8 cm long, 0.7-3.6 mm wide, flat or loosely folded, finely pilose above and scabrous below, margins scabrous, apex mostly acuminate, rarely acute. Panicles (0.5-)1-7 cm long, 2-9 mm wide, tightly spiciform, often interrupted below, elliptic to oblong, terminal and axillary, often partially included in the sheath below; primary branches 4-15 mm long, tightly ascending-appressed, verticillate below with 5-10 per node, scabrous; pedicles 0.1-1.2 mm long, shorter than the spikelets, scabrous. Spikelets 3.4-4.6 mm long, 1-flowered, tightly carinate, cleistogamous; glumes 3.5-4.7 mm long, longer than the floret, nearly equal in length, membranous, linear lanceolate, 1-veined, scaberulous along the midvein, apex acuminate, mucronate, the mucro 0.2-0.7 mm long; lemmas 1.5-2.1 mm long, hyaline to membranous, ovate, 3-veined, the lateral veins faint, mottled with irregular plumbeous areas, sparingly appressed pilose, the hairs 0.2-0.4 mm long, apex truncate to obtuse, subapically awned, the awns 1.2-5 mm long, straight; callus pilose; paleas 1.4-2 mm long, hyaline, ovate, sparingly pilose, apex truncate, the veins extending as mucros up to 0.2 mm long; lodicules 0.1-0.2 mm long, truncate; stamen 1, anthers 0.3-0.6 mm long, whitish to yellow. Caryopses 1-1.6 mm long, ovoid, laterally flattened, light brown.

Distribution.

A Peruvian endemic known only from near San Jose de Canta, Peru.

Ecology.

This species occurs on gravelly slopes among xerophytic scrub vegetation with Bouteloua simplex , Eragrostis mexicana subsp. virescens (J. Presl) S.D. Koch & Sánchez Vega, Muhlenbergia bryophilus , Urochloa sp., Veronica sp. and Festuca myruos between 2700 and 2800 m.

Comments.

Molecular DNA sequence analysis indicates Muhlenbergia monandra is an unsupported sister to the M. atacamensis - M. ligulata - M. subbiflora clade in M. subg. Pseudosporobolus (Fig. 1B ).

Specimens examined.

Peru. Lima: Prov. Canta, 8 km SW of San Jose Canta towards Huamantango, 11°31'10.0"S, 76°42'16.3"W, 2770 m, 28 Mar 2004, P.M. Peterson & N. Refulio Rodriguez 17990 (MO, US, USM); entre Huamantanga y Puruchuco, 2800 m, 1 May 1994, J.J. Alegría Olivera 739 (MOL, SI).

Figures

Figure 1. A, B Maximum-likelihood 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 red occur in South America; scale bar = 2 %.

Figure 10. A-M Muhlenbergia monandra Alegria & Rugolo A habit B ligule C two spikelets D glume base and rachilla E lemma, dorsal view F floret, side view G floret, ventral view H apex of lemma with two small teeth I palea and caryopsis, lateral view J lodicules K caryopsis, dorsal view L caryopsis, lateral view M caryopsis, ventral view. Drawings from the holotype collection Granda Paucar & Alegria Olivera 2230.