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).