Systematic Botany (2011), 36(1): pp. 53–58 © Copyright 2011 by the American Society of Plant Taxonomists DOI 10.1600/036364411X553126 New Species of Paniceae (Poaceae, Panicoideae) from Brazil Diego L. Salariato , 1 , 2 Osvaldo Morrone , 1 and Fernando O. Zuloaga 1 1 Instituto de Botánica Darwinion, Labardén 200, Casilla de Correo 22, B1642HYD, San Isidro, Buenos Aires, Argentina 2 Author for correspondence ( [email protected] ) Communicating Editor: Molly Nepokroeff Abstract— Two new species of Paniceae are here described, one belonging to Dichanthelium ( Dichanthelium barbadense ) and the other to Panicum sect. Laxa ( Panicum harleyi ). Both taxa grow in open areas of Central Brazil are described, illustrated, and compared with putative related species. Keywords— Dichanthelium , Gramineae , grasses , Panicum , taxonomy. During a revision of the Paniceae for the Neotropics, two to sparsely pilose, subcordate at the base, the apex acute, mar- new species were discovered from Brazil and are described gins long-ciliate, scabrous, involute toward the apex. Peduncle below. One belongs to Dichanthelium (Lam.) Gould and the up to 3 cm long, included in the uppermost leaves or partially other is placed in Panicum sect. Laxa (Hitchc. & Chase) Pilg. exerted, shortly pilose to glabrous. Inflorescence 3–5 × 1–2 cm, Dichanthelium an American genus with nearly 55 species dis- lax, few flowered panicle; main axis wavy, sparsely pilose tributed from Canada and the U. S. A. to Argentina ( Zuloaga near the branches, otherwise smooth, glabrous; pulvini pilose, et al. 1993 ; Aliscioni et al. 2003 ) is characterized as including with long whitish hairs; first order branches up to 0.8 cm long, perennial species with or without foliar dimorphism, mem- divergent or appressed, alternate, axis of the branches smooth, branous-ciliate ligules, spikelets ellipsoid to obovoid with glabrous, delicate, terete; pedicels 2–5 mm long, claviform, the upper glume and lower lemma (5–)7–15 nerved, and the with long whitish hairs toward the base. Spikelets 3–3.2 × 1.2– upper anthecium indurate, with simple papillae all over its 1.4 mm, long-ellipsoid, acute, green or tinged with purple, gla- surface; anatomically, species in this genus have a C3 photo- brous, upper glume and lower lemma acuminate, exceeding synthetic pathway, with several mesophyll cells between each the upper anthecium in length. Lower glume 1.2–1.6 mm long, vascular bundle and conspicuous adaxial and abaxial exten- ca. ½ or less the length of the spikelet, ovate, subulate, hyaline, sions radiating from outer vascular bundle. Panicum sect. glabrous, 1–3-nerved, the nerves not manifest, not embrac- Laxa includes, as presently circumscribed ( Zuloaga et al. 1992 ; ing the upper glume. Upper glume as long as the spikelet, Aliscioni et al. 2003 ), 10 species; of these, nine grow in the glabrous to sparsely pilose, 9–11-nerved, tinged with purple New World, while P. auritum J. Presl ex Nees is restricted to at the apex. Lower lemma as long as the spikelet, glumiform, Asia. Species of this section have biconvex spikelets arranged glabrous to sparsely pilose, 9-nerved. Lower palea 2.4–2.6 × in unilateral branches, with the lower glume 1–3-nerved, the 1.2 mm, ovate, hyaline, the margins ciliolate, apex acute; lower upper glume and lower lemma 5–nerved, and the upper anth- flower absent. Upper anthecium 2.4 × 1.2 mm, ellipsoid, apicu- ecium membranous, with simple papillae and prickle hairs late, pale, with simple papillae regularly distributed all over its toward the apex; anatomically, all species of sect. Laxa are C3 , surface, shortly pilose at the apex ( Fig. 2 ); lodicules ca. 0.4 mm several of them with conspicuous fusoid cells near the vascu- long, 2, truncate; stamens 3. Caryopsis not seen. Figure 1 . Copyright (c) American Society for Plant Taxonomists. All rights reserved. Delivered by Ingenta to IP: 192.168.39.210 on: Mon, 27 Sep 2021 03:46:23 lar bundles. Etymology— The name refers to the locality “Pico do Barbado”, type locality of the species. Pico do Barbado is the highest mountain in the Brazilian state of Bahia. Taxonomic Treatment Distribution and Habitat— Only known from “campos rup- estres,” rock fields, of Chapada Diamantina in Bahia, where Dichanthelium barbadense Salariato, Morrone & Zuloaga, this rare species grows in open, shrubby savannas, between sp. nov.—TYPE: BRAZIL. Bahia: Abaíra, Pico do Barbado, 1,100 and 2,400 m elevation, together with species of Apochloa 13°17¢0.04²²S, 41°55¢59.94²W 1,800–2,430 m, 15 Aug 1998, Zuloaga & Morrone and Renvoizea Zuloaga & Morrone A. M. Giulietti, G. L. Campos, A. S. Conceição, A. T. Brito & (Poaceae), and genera of Velloziaceae and Eriocaulaceae. R. P. Oliveira 1454 (holotype: HUEFS!). Observations— Dichanthelium barbadense is related, by its dis- Dichanthelium congesto affine sed spiculis non stipitatis, tribution and morphology, to D. congestum (Renvoize) Zuloaga gluma inferiore ½ spiculam aequans vel breviore, gluma and D. stipiflorum (Renvoize) Zuloaga; all these species grow superiore 9–11-nervia, differt. within the Espinhaço range, Chapada Diamantina, in north- Short rhizomatous perennials, caespitose. Culms 15–40 cm eastern Brazil, although they do not overlap in its present dis- tall, many noded, erect, freely branching, more so toward the tribution. Dichanthelium congestum differs by having a lower middle and upper nodes; internodes 0.5–3 cm long, hollow, glume ¾ or more the length of the spikelet, 5–7-nerved, with terete, shortly pilose, barbate; nodes compressed, dark, pilose. a conspicuous internode between both glumes. Dichanthelium Sheaths 1.2–3 cm long, usually longer than the internodes, stipiflorum is distinguished by its cordate, clasping blades, and overlapping, striate, the margins long ciliate toward the apex, spikelets densely hirsute with a conspicuous stipe between otherwise sparsely pilose to glabrous. Ligules 0.2–0.4 mm the lower and upper glume. Dichanthelium barbadense shares, long, membranous- ciliate, the membranous portion reduced, with other species of Dichanthelium , a non Kranz anatomy, with long hairs beneath at the base of the blade; collar pale, with more than four mesophyll cells between consecutive pilose. Blades 1–3 × 0.4–0.5 cm, ovate-lanceolate to lanceo- vascular bundles, and also extensions of the outer bundle late, flat, hispid on both surfaces with papillose-pilose hairs sheath adaxially and abaxially ( Fig. 3, A-B ). 53 54 SYSTEMATIC BOTANY [Volume 36 Copyright (c) American Society for Plant Taxonomists. All rights reserved. Delivered by Ingenta to IP: 192.168.39.210 on: Mon, 27 Sep 2021 03:46:23 Fig. 1. Dichanthelium barbadense . A. Habit. B. Detail of ligule. C. Spikelet, ventral view. D. Spikelet, dorsal view. E. Lower palea. F. Upper anthecium, dorsal view. G. Upper anthecium, ventral view. H. Upper lemma. I. Upper palea with lodicules and filaments (based on Giulietti et al. 1454 ). Key to D. BARBADENSE and Related Species The following key provides a delimitation of D. barbadense from species of the genus with a similar geographic distribution. 1. Blades clasping the culm, cordate, width length to width ratio of 3–5(–7):1 . 2 2. Upper glume and lower lemma 5(–7)-nerved, the nerves inconspicuous, lower lemma inflated at base; upper anthecium inserted laterally in relation to the axis of the rachilla . Dichanthelium sciurotis (Trin.) Davidse 2011] SALARIATO ET AL.: NEW SPECIES OF PANICEAE 55 2. Upper glume and lower lemma 7–9-nerved, with prominent nerves; lower lemma not inflated at base; upper anthecium inserted horizontally in relation to the axis of the rachilla . 3 3. Inflorescences 1–2.5(–3) cm long, few–flowered; blades overlapping, 1–3 cm long, 0.3–0.6 cm wide . Dichanthelium cumbucana (Renvoize) Zuloaga 3. Inflorescence 2.5–15 cm long, multiflowered; blades not overlapping, 2–12 cm long, 0.5–2 cm wide . 4 4. Spikelets 1.5–2.5 mm long, without a manifest stipe between the lower and upper glume . 5 5. Spikelets short-hispid, 1.5–1.9 mm long; inflorescences 2.5–9 cm long; main axis of the inflorescence densely hirsute; blades ovate-lanceolate, with base asymmetrical . Dichanthelium sciurotoides (Zuloaga & Morrone) Davidse 5. Spikelets glabrous, 1.7–2.5 mm long; inflorescences 10–15 cm long; main axis glabrous; blades linear-lanceolate, with base symmetrical . Dichanthelium aequivaginatum (Swallen) Zuloaga 4. Spikelets 2.2–3.3 mm long, with a stipe between the lower and upper glume . 6 6. Blades with margins cartilaginous and covered with manifest cilia; lower glume ½ or less the spikelet; blades with base symmetrical . Dichanthelium stipiflorum (Renvoize) Zuloaga 6. Blades without cartilaginous margins and without cilia on the upper portions of the margins; lower glume 1/2–3/4 the length of spikelet; blades with base asymmetrical . Dichanthelium pycnoclados (Tutin) Davidse 1. Blade not clasping the culm, narrow to subcordate, width length to width ratio of 10–30:1 . 7 7. Lower glume ¼–1/2 the length of the spikelet . 8 8. Plants with prominent glands on sheaths, blades and axis of the panicles . Dichanthelium adenorhachis (Zuloaga & Morrone) Zuloaga 8. Plants without prominent glands on sheaths, blades and axis of the panicles, occasionally present on the axis of the panicle . 9 9. Blades 3.5–12(–16) cm long. 0.2–1.3(–1.5) cm wide; panicles 10–15 cm long . Dichanthelium aequivaginatum (Swallen) Zuloaga 9. Blades 1–3(–6) cm long, 0.2–0.5 cm wide; panicles 3–5 cm long . 10 10. Spikelets 2–2.3 mm long, ellipsoid, hirsute, covered with whitish hairs; blades linear-lanceolate . Dichanthelium cabrerae (Zuloaga & Morrone) Zuloaga 10. Spikelets 2.5–3.2 mm long, long-ellipsoid, glabrous to sparsely pilose, blades ovate-lanceolate to lanceolate . Dichanthelium barbadense Salariato, Morrone & Zuloaga 7. Lower glume ¾–4/5 the length of the spikelet . 11 11. Spikelets with a stipe between the lower and upper glume .