Poa ramoniana Soreng & S.P. Sylvester, 2016

Sylvester, Steven P., Soreng, Robert J., Peterson, Paul M. & Sylvester, Mitsy D. P. V., 2016, An updated checklist and key to the open-panicled species of Poa L. (Poaceae) in Peru including three new species, Poa ramoniana, Poa tayacajaensis, and Poa urubambensis, PhytoKeys 65, pp. 57-90 : 75

Poa ramoniana Soreng & S.P. Sylvester sp. nov. Fig. 1

Type.

PERU. Región JUNÍN. Prov . Junín: Distr. Carhuamayo , orillas de la laguna de Capillacocha, {est. vicinity: S10.86443°, W75.99256°} entre Carhuamayo y Paucartambo, Puna grassland, 4200-4300 m, 8 Jan 1949, R. Ferreyra 5200 p.p. a (holotype: US-2207173!; isotype: USM p.p.)

Plants gynomonoeious. Perennials; Rhizomatous, with well developed, slender, lateral tending, rhizomes, small tufted. Tillers extravaginal. Culms c. 5 cm tall, erect, unbranched, isolated or two together; Culm nodes terete, smooth, included in the sheaths; Culm internodes less than 1 cm long (peduncle c. 3 cm), terete, smooth. Leaves equally basal and cauline; Sheaths slightly laterally compressed, keeled, smooth, glabrous; Butt sheaths papery or slightly fibrous in age; Uppermost culm sheath c. 18 mm long, margins fused c. 40% their length, distal sheaths longer than their blades; Collars and throats smooth, glabrous; Ligules 1-1.5 mm long, sometimes with a central dent to 2 mm long, indistinctly decurrent, abaxially moderately densely scabrous, apices obtuse, margin irregular sometimes with a tooth, of sterile shoots similar to those of the culm; Cauline blades to 2 cm long, mostly folded or infrequently flat, with strongly inrolled margins, abaxially, marginally, and adaxially smooth, glabrous, tips distinctly prow shaped; Blades graduated up the culm, the sub-terminal one the longest; Sterile shoot blades to 4.5 cm long. Panicles 2-2.5 cm long, open, exerted, c. 1 cm wide, with 13-15 spikelets, proximal internode c. 6 mm long, weakly scabrous angled; Rachis with 1 branch per node; Primary branches spreading to reflexed, the upper ones ascending, distinctly angled, closely scabrous along the angles; Lateral pedicels less than 0.5 mm long, scabrous angled; Longest branches c. 7 mm, with 4-5 spikelets clustered in the distal half. Spikelets 3.5-4 mm long, c. 1.5 × longer than wide, broadly ovate, laterally compressed, not bulbiferous, anthocyanic and bronzy; Florets (2-)3, the proximal 1 (or 2 if 3 total) perfect, the distal 1 pistillate; Rachilla internodes 0.4-0.8 mm long, terete, distal internodes terete, smooth, glabrous, mostly hidden; Glumes more or less equal, both broadly lanceolate, or the first lanceolate, sub-lustrous in the scareous-hyaline margins, distinctly keeled, keels smooth or distally smooth or sparsely scaberulous, apices acute and pointed to obtuse and blunt and denticulate; Lower glumes 2.5-3 mm long, 1-3-veined; Upper glumes 3-3.2 mm long, subequal in width to the lower, 2-3-veined; Calluses glabrous; Lemmas (the lowest) 2.9-3.5, 5-veined, broadly lanceolate to ovate, green proximally, anthocyanic distally with a wide bronzy band apically, strongly laterally compressed, distinctly keeled, thin, keel smooth or obscurely scaberulous distally, smooth or mostly smooth elsewhere, glabrous, intermediate veins distinct, not extending into the scarious apical margin, edges smooth, apices scarious-hyaline bronzy for the distal c. 1 mm, edges smooth or slightly erose to denticulate, obtuse, blunt or slightly pointed; Paleas to 1 mm shorter than the lemma, glabrous, keels smooth or distally sparsely scaberulous. Flowers chasmogamous; Lodicules not observed; Anthers c. 2 mm long (vestigial in pistillate flowers). Caryopses unknown. 2 n = unknown.

Distribution.

Known only from a single locality in Junín.

Habitat.

Puna grassland, 4200-4300 m, in wet margins/shore of lakes, in moss.

Etymology.

The species is named in recognition of the eminent Peruvian botanist, Ramón Alejandro Ferreyra (1910-2005) who collected the type and paratype.

Conservation status.

Data insufficient.

Additional specimens examined.

PERU. Región JUNÍN. Prov . Junín: Distr. Carhuamayo, Capillacocha cerca a Carhuamayo, Puna grassland, 4200-4300 m, 8 Jan 1949, R. Ferreyra 5211 (USM!) .

Discussion.

This new species appears like a small form of Poa glaberrima , but differs by being extensively rhizomatous and reaching only 5 cm tall, versus densely tufted and 12-45 cm tall for Poa glaberrima . The US holotype of Poa ramoniana is a mixed collection, with a second taxon p.p. “b”, which appears to be Poa gymnantha Pilg. that is sterile, tightly tufted, with intravaginally branching shoots and involute leaf blades that are adaxially scabrous. The USM isotype also contains two species: the small rhizomatous plant is Poa ramoniana ; the taller plants appear to be Poa glaberrima . Tovar originally determined the USM type and paratype as Poa lilloi ( Tovar 1993), which, among other differences, has a dense habit, without rhizomes, and ascending panicles branches, densely scabrous lemmas with narrow white, scarious margins, and sometimes a web on the callus. Tovar also identified the US type as Poa ovata Tovar (1965: 17), which RJS considers to be a rare to uncommon sexually reproducing phase of the small form of Poa gymnantha , a species that is otherwise predominantly pistillate and apomictic ( Negritto et al. 2008). Other material determined as Poa lilloi in Peru has been referred to Poa glaberrima and Poa candamoana , or small Poa kurtzii (see excluded species, below).

Figures

Figure 1. Poa ramoniana. A Habit B Ligular zone C Terminal segment of inflorescence branch with four spikelet cluster D Spikelet E Lower glume ventral view F Proximal floret (perfect) G Upper glume dorsal view H Palea with immature pistil (pistillate floret), dorsal view I Palea with pistil (pistillate floret), staminodes, and lodicules, lateral view. Drawn from type material (R. Ferreyra 5200 p. p. a, US- 2207173).