Deschampsia santamartensis Sylvester & Soreng, 2019

Sylvester, Steven P., Soreng, Robert J., Bravo-Pedraza, William J., Cuta-Alarcon, Lia E., Giraldo-Canas, Diego, Aguilar-Cano, Jose & Peterson, Paul M., 2019, Paramo Calamagrostis s. l. (Poaceae): An updated list and key to the species known or likely to occur in paramos of NW South America and southern Central America including two new species, one new variety and five new records for Colombia, PhytoKeys 122, pp. 29-78 : 29

Deschampsia santamartensis Sylvester & Soreng sp. nov. Fig. 2

Type.

COLOMBIA. Magdalena: Sierra Nevada de Santa Marta, valley descending south-western from Picos Reina and Ojeda, rocky and sandy páramos above Laguna Naboba and Laguna Reina, superpáramo, 4300-4500 m alt., 5 Oct. 1959, J. Cuatrecasas & R. Romero Castañeda 24607 (holotype: COL (COL000184738!); isotype: US (US01240776!)).

Diagnosis.

Deschampsia santamartensis is similar to Deschampsia hackelii (Lillo) Saarela, but differs in having broad, rigid and erect, strongly conduplicate blades, 1.5-2.5 mm when folded (vs. filiform and curved leaf blades 0.5-1 mm wide when folded), ligules short and often truncate or obtuse with ligules of innovations 0.5-1 mm long and ligules of upper flowering culms 3-4 mm long (vs. ligules long and acuminate 3.5-7 mm long), ellipsoid spike-like panicles 3-5.5 long × 1.5-2.5 cm wide (vs. capituliform spherical panicles 1-3 cm long × 1-2 cm wide), lemma surfaces moderately to lightly scabrous between the veins (vs. smooth), lemma apices acute to muticous and entire (vs. truncate and irregularly dentate), rachilla extension often absent (vs. always present, 0.5-1 mm long) and inside of the floret often with hyaline shiny sinuous trichomes to 1 mm long emerging from the base of the ovary (vs. lacking trichomes).

Description.

Tufted perennial forming short dense tufts with vertical rhizomes and papyraceous, fibrous basal sheaths, leaves form a basal mat to 12 cm tall and much shorter than the exerted culms. Tillers intravaginal. Culms 9-20 cm tall, 1-1.5 mm wide, erect, exerted from the basal foliage, not obviously striate, densely papilliate; nodes and internodes terete, densely papilliate, not lustrous, nodes hidden in the sheaths with no nodes exposed at flowering; uppermost internodes 10-18 cm long, longer than the sheaths. Sheaths weakly striate, slightly keeled; flag leaf sheaths 7-10 cm long; upper culm sheaths lax, glabrous, smooth, densely papilliate; basal leaf sheaths 2-3 cm long, longer than the internodes, glabrous, smooth or slightly scabrous, densely papilliate, older basal sheaths papyraceous and fibrous with the fibres becoming slightly curly as the sheaths decay and leave just the fibres. Ligules not stipulate; upper culm ligules 3-4 mm long, regularly decurrent with the sheaths, broadly shouldered with an attenuate central point, hyaline, without notable lateral keels, apices entire or irregularly dentate, abaxial surface smooth and sparsely papilliate; ligules of innovations 0.5-1 mm long, strongly decurrent with the sheaths, broadly shouldered and sometimes with a lateral extension or lobe that extends ca. 1 mm long, the centre of the ligule truncate to obtuse and irregularly dentate, hyaline, without notable lateral keels, abaxial surface scabrous with distinct, mostly retrorse, spinules, with spinules tending to run down the throat and occur on the collar margin. Leaf blades 2.5-8 cm long, 1.5-2.5 mm wide when folded, gradually reduced up the culm, strongly conduplicate with margins frequently inrolled, weakly keeled, erect to slightly divergent, glabrous, abaxial blade surface smooth, strongly papilliate, adaxial blade surface scabrous mainly in the centre in lines along the veins, veins pronounced, margins moderately scaberulous, apex naviculate with a slightly pungent mucronate point; flag leaf blade 1.7-3 cm long, slightly narrower than lower culm blades. Panicles 3-5.5 cm long, 1.5-2.5 cm wide, dense, ellipsoid, golden-purple, densely spiculate, sometimes interrupted towards the base, spikelets present from near the base; main panicle axis terete, glabrous, smooth, lower internode ca. 1 cm long; panicle branches short, ascending; primary panicle branches 1-2 cm long, bearing 15-50 spikelets per branch, verticillate in clusters of 1-3, terete, glabrous, almost smooth to lightly scabrous, papilliate; pedicels 0.5-1.5 mm long, much shorter than the spikelets, glabrous, lightly scabrous, papilliate. Spikelets 1-flowered, strongly laterally compressed, disarticulating above the glumes (not seen); glumes, lemma and palea slightly asymmetrical. Glumes 4.6-5.5 mm long, subequal or rarely unequal, lower glumes 0.5-1.5 mm shorter than the upper glumes, membranous, purplish grading to a scarious golden-bronze margin, sub-lustrous, papilliate, very sparsely scabrous on the keels, edges smooth, apices acute to acuminate, entire to infrequently irregularly denticulate; lower glume 1-veined; upper glume 3 or sometimes faintly 5-veined, lateral veins reaching half the length of the glume. Florets stipitate, single, included in the glumes, subequalling the apex of the lower glume. Lowermost rachilla internode (0.25 –)0.4– 0.5 mm long, prolonged between the glumes and the floret, terete, slightly dilated at its apex, glabrous, smooth. Lemmas 4-4.5 mm long, of the same consistency as the glumes, golden-purple with a broad scarious margin and apex, glabrous, long scabrous to pectinate scabrous along the keel for most its length, lemma surface moderately to sparsely scabrous between the veins distally for up to ¾ the length of the lemma, apex slightly falcate, acute to muticous, entire, apex margins broadly scarious and somewhat incurved, 5-veined, veins generally not evident, sometimes apparent towards the base; awn absent. Paleas slightly shorter than the lemma, of the same consistency, golden, scarious, keels closely spaced with the keel flanges twice as broad as the gap between the keels, one keel more pronounced than the other, regularly scabrous and notable in the upper 2/3 of the length, scabrous between the keels, apex sometimes inconspicuously bidentate. Callus base rounded and slightly dorsally compressed above, glabrous. Rachilla absent or to 0.6(-1) mm long, glabrescent with a few short hairs at the apex. Lodicules 2, ca. 0.4 mm long, as broad as long, membranous, flabellate, with an acute lobe. Stamens 3, anthers 2-2.2 mm long. Ovary ca. 0.6 mm long, small, styles 2, stigmas plumose with secondary branching, short, often with scarce hyaline, shiny and sinuous trichomes to 1 mm long emerging from the base of the ovary. Caryopsis ca. 2 mm long, ca. 0.6 mm wide, obovate, laterally compressed in cross section, hilum 0.2 mm long, circular to obovate, ventral groove shallow and narrow and not conspicuous, pale honey brown, embryo ca. 0.4 mm long, apex with remains of style bases <0.1 mm long, with remains of short plumose stigmas attached; endosperm liquid.

Distribution and ecology.

Known only from the type specimen that was collected from a southwest facing valley descending from Picos Reina and Ojeda in the centre of the Sierra Nevada de Santa Marta. The specimen was collected from high elevation rocky and sandy superpáramo vegetation above 4300 m.

Preliminary conservation status.

Data Deficient (DD). Currently known only from a single specimen. Further expeditions are needed to the Sierra Nevada de Santa Marta to document its distribution.

Etymology.

The species epithet refers to the type locality of the Sierra Nevada de Santa Marta.

Notes.

Deschampsia santamartensis clearly belongs to Calamagrostis subsect. Stylagrostis (= Deschampsia sensu Saarela et al. 2017) due to the presence of an extended rachilla internode between the glumes and the floret. Deschampsia santamartensis can be easily distinguished from all other members of Calamagrostis subsect. Stylagrostis with dense, spike-like panicles by its florets lacking awns, a glabrous callus and the absence of a rachilla extension (or rarely with a diminutive glabrescent rachilla extension). The only other member of Calamagrostis subsect. Stylagrostis with dense spike-like panicles, glabrescent callus, glabrescent short rachilla extensions and which occasionally lack awns is Deschampsia hackelii (Lillo) Saarela (= Calamagrostis hackelii Lillo), a species known from high-Andean regions of northwest Argentina and Chile ( Rúgolo de Agrasar 2012: 201). Deschampsia hackelii differs by its capituliform panicles, 1-3 cm long × 1-2 cm wide (vs. ellipsoid spike-like panicles 3-5.5 long × 1.5-2.5 cm wide), filiform and curved leaf blades 0.5-1 mm wide when folded (vs. broad, rigid and erect, strongly conduplicate blades 1.5-2.5 mm when folded), long acuminate ligules 3.5-7 mm long (vs. ligules short and often truncate or obtuse with ligules of innovations 0.5-1 mm long and ligules of upper flowering culms 3-4 mm long), lemma surfaces smooth (vs. moderately to lightly scabrous between the veins), lemma apex truncate and irregularly dentate (vs. acute to muticous and entire), rachilla extension always present 0.5-1 mm long (vs. often absent) and inside of the floret lacking trichomes (vs. often with hyaline shiny sinuous trichomes to 1 mm long emerging from the base of the ovary).

Deschampsia aurea , a species originally described from Ecuadorian páramos but which also occurs in Peruvian Jalca vegetation, is another member of Calamagrostis subsect. Stylagrostis that has dense, spike-like panicles and spikelet lemmas that occasionally lose the thin weak dorsally-inserted awn (Zulma Rúgolo de Agrasar, pers. comm.). Deschampsia aurea has well-developed callus and rachilla hairs, with callus hairs surpassing more than half the length of the lemma and rachilla hairs reaching or surpassing the lemma apex, as well as other characters to help differentiate it from D. santamartensis such as the floret being noticeably shorter (2.9-3 mm long) than the large glumes (5.5-7.5 mm long), amongst other characters. Calamagrostis chrysostachya (E. Desv.) Kuntze, a species known from high-Andean regions of northwest Argentina and Chile, also shares these attributes and has also been included as a member of Calamagrostis subsect. Stylagrostis ( Rúgolo de Agrasar 2012, pers. comm.). Both these species, however, have a pilose callus and rachilla, with C. chrysostachya having poorly developed callus and rachilla hairs to 1 mm long, but thin conduplicate or convolute leaf blades 0.8-1.2 mm wide when unfolded and a ligular stipule 0.5-1.5 mm long. The short, strongly conduplicate leaf blades with navicular apices are also reminiscent of Poa trachyphylla Hack. which also inhabits high-elevation superpáramo of Colombia ( Sylvester et al. in press).

Figures

Figure 2. Deschampsia santamartensis. A Habit B Ligule C Panicle branch D Spikelet E spikelet, with lower glume pulled away to reveal the stipitate floret (extension of the lowermost rachilla internode) F floret G floret, with palea and lemma slightly separated to reveal the ovary in a late stage of development and surrounded by long filamentous trichomes H floret, with palea and lemma slightly separated to reveal the stamens and ovary at an earlier stage of development and surrounded by long filamentous trichomes; drawn by Marcela Morales from the holotype, J. Cuatrecasas & R. Romero Castaneda 24607 (COL).