Poa sanchez-vegae Soreng & P.M. Peterson, 2016

Peterson, Paul M. & Soreng, Robert J., 2016, A revision of Poa subsection Aphanelytrum (Poaceae, Pooideae, Poaeae, Poinae); and a new species, Poa auriculata, PhytoKeys 63, pp. 107-125 : 114

Poa sanchez-vegae Soreng & P.M. Peterson nom. nov. Fig. 2 A–C , 4A, B, D–L

Aphanelytrum peruvianum Sánchez Vega, P.M. Peterson, Soreng & Lægaard, J. Bot. Res. Inst. Texas 1(2): 842. 2007.

Type.

PERU. Departamento Cajamarca, Provincia Cajamarca, Distrito Cajamarca, Cerro Akumullca, al SO de Cajamarca, sobre la cima de la ladera occidental del Valle de Cajamarca (7°14'15"S Lat, 78°29'24"W Long), 3300 m, 20 Mar 2003, I. Sánchez-Vega 11781, M. Sánchez-Montoya, R. Cueva R. & J. Montoya (holotype: CPUN!; isotypes: AAU!, F!, HAO!, HUT!, LOJA!, MICH!, MO!, SI!, US-3472470!, US-3686568!, USM!).

Description.

Caespitose perennials. Culms 14-24 cm tall, with many culms near base, primary and secondary culms appressed, somewhat decumbent near base with intravaginal branching, culm bases continuously branch and often root at low to mid-culm nodes; internodes 3-18 mm long, numerous. Leaf sheaths longer than the internodes, membranous to hyaline, open to near base to open completely to base, slightly keeled; ligules 2-3 mm long, membranous to hyaline, decurrent, apex erose often lacerate; blades 3-7 cm long (flag leaf ca 1.6 mm long), 0.2-1.2 mm wide, flat to loosely involute, thin, linear, apex naviculate. Panicles 1.7-2.5 cm long, few-flowered with 5-10 spikelets; branches flexuous, the lower branches with two spikelets, the upper branches with single spikelet. Spikelets 5-7 mm long, usually 3-flowered, purplish, glabrous, disarticulating above the glumes and between the florets; lower and middle florets usually staminate; upper florets usually pistillate; rachilla joints 1.2-2 mm long, prolonged above the upper floret; glumes 1-2 mm long, subequal, apex acute, often mucronate; lower glume linear, 1-veined; upper glume oblanceolate, 3(4-)-veined, often toothed or irregularly lobed minutely bifid; lemmas 2.2-3.5 mm long, 3- or 5-veined, ovate, apex mucronate with two acute lobes on each side of the mucro, the mucro 0.1-0.3 mm long; paleas 2-3.2 mm long, 2-keeled, apex bifid; lodicules 0.7-0.8 mm long, lanceolate, membranous, glabrous; stamens 3; anthers 2-2.9 mm long, yellowish to purplish; ovaries glabrous with two styles and two stigmas. Caryopses glabrous.

Leaf anatomy.

The transverse section leaf anatomy of Poa sanchez-vegae is C3, XyMS+ with non-radiate, spongy chlorenchyma, without adaxial palisade cells (Fig. 2 A–C ). There are bulliform cells on the adaxial surface on either side of the midveins primary vascular bundle without additional sclerenchyma (Fig. 2B ). However, there are a few abaxial sclerenchyma cells associated with the lateral primary vascular bundles (Fig. 2C ).

Phenology.

Flowering in March.

Distribution.

Poa sanchez-vegae is known only from the type locality near the western highlands of the Cajamarca Valley and is found on rocky sites associated with jalca vegetation (humid alpine grass ecosystems) at 3300 m ( Sánchez-Vega et al. 2007).

Conservation status.

Poa sanchez-vegae is rare and the conservation status is data deficient ( IUCN 2010). However, the authors unsuccessfully searched for additional material of this species at the type locality on 26 Mar 2008, accompanied by two of the original collectors, Isidoro Sánchez-Vega and Juan Montoya. The site had been turned into a pine plantation.

Etymology.

Since the existing specific epithet was occupied in Poa we provide a new name commemorating Isidoro Sánchez Vega, a renowned Peruvian Botanist.

Comments.

Based on morphological characters, Isidoro Sánchez-Vega in consultation with Simon Lægaard, first identified the type collection of Poa sanchesz-vegae as an unknown species of Aphanelytrum . In Sánchez Vega et al. (2007), we described this taxon as a new Aphanelytrum , and mention that Festuca reclinata superficially resembled the genus. In addition, Poa sanchez-vegae aligned near or on an unusually long branch within Poa in preliminary cpDNA and ITS sequence analyses ( Gillespie et al. 2007). Gillespie et al. (2008) included three accessions of Poa hitchockiana (≡ Aphanelytrum procumbens ) that formed a clade sister to Poa sanchez-vegae (≡ Aphanelytrum peruvianum ) which together was sister to two accessions of Poa apiculata (≡ Tovarochloa peruviana ). These results clearly support our classification of Poa sanchez-vegae and Poa hitchcockiana as members of Poa subsect. Aphanelytrum .

Figures

Figure 2. Leaf blade transverse sections of Poa sanchez-vegae (A - C) and Poa hitchcockiana (D). Poa sanchez-vegae: A Entire leaf blade B Midvein showing a single primary vascular bundle with bulliform cells (b indicated by arrows) C Lateral primary vascular bundle with a few associated abaxial sclerenchyma fibers (sf) and spongy chlorenchyma (chl). Poa hitchcockiana: D Midvein showing a single primary vascular bundle with abaxial sclerenchyma fibers (sf) and collapsed chlorenchyma.

Figure 4. Poa sanchez-vegae (A, B, D-L) and Poa hitchcockiana (C). Poa sanchez-vegae: A Habit B Sheath, ligule, and blade D Panicle E Spikelet F Glumes, showing lower 1 - veined and upper 4 - veined G Glumes, showing lower 1 - veined and upper 3 - veined H Lemma I Paleas J Palea, anthers, and rachilla K Lodicules and pistil L Pistil. (Sanchez Vega 11781, Sanchez Montoya, Cueva R. & Montoya, US- 3472470, US- 3686568). Poa hitchcockiana: C Sheath, ligule, and blade (Peterson 16571 & Refulio Rodriguez).