Bromus alonsae G. Leofanti & M. L. Echeverria 2024, sp. nov.
Creators: name: Leofanti, Gabriela Agustina
name: Echeverría, María Lis
name: Méndez, Alicia López
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Liliopsida
Poales
Poaceae
Bromus
Bromus alonsae

description: Bromus alonsae G. Leofanti & M.L. Echeverría sp. nov.
(Figs. 2A–E, 3A–H; Table 1).
Type:— ARGENTINA. Buenos Aires, Partido Mar Chiquita, La Caleta, al borde del camino costero, a ambos lados de un canal, 37°46’52.3” S, 57°27’12.4” W, 4 m a.s.l, 4 November 2019, M.L. Echeverría & G.A. Leofanti 229 (holotype BAL! 317; isotype BA!).
The new species, B. alonsae, is similar to B. catharticus var. catharticus but differs in growth habit (perennial with creeping or semi-creeping habit vs. annual or briefly perennial with erect or semi-erect habit), blade color (glaucous green vs. light green), blade pubescence (short and dense vs. variable to glabrous), vernation (folded to rolled vs. rolled), and flowering period (mid-October to late January vs. early September to mid-March).
Description: — Plants perennial, cespitose, with high tiller production, with records up to 81 per plant, and variable vernation, folded or rolled, in the same individual. Culms 20.5–46.5 cm tall, decumbent; nodes 4–8, glabrous to pubescent. Leaf sheaths 5.5–12.5 cm long, usually pubescent, sometimes glabrous, closed for most of their length and open at the upper part; auricles absent; ligules 2–4 mm long (Fig. 3B), membranous, apex lacerate; blades 17–35 cm long, glaucous-green, linear, flat, with short dense pubescence. Panicles (Fig. 3E) 15.6–25 cm long, loose, elliptic-pyramidal, semi-contracted, with 28–105 spikelets; branches close to the main axis; lower branches 7.2–10.6 cm long and upper branches 2.4–5 cm long; pedicels 0.1–2.1 cm long. Spikelets (Fig. 3F) 1.7–3.6 × 0.4–1 cm, ovate-lanceolate, laterally compressed, with 6–10 florets; glumes glabrous, ovate-lanceolate, usually unequal, the upper one 1–3 mm longer than the lower one, persistent, longer than half the length of the lowest lemma, apex acute and keeled; lower glume 0.8–1.5 cm long, 5–8 nerved; upper glume 0.9–1.7 cm long, 7–9 nerved; lemma (Fig. 3G) of the basal floret lanceolate, 1.1–2.2 cm long, 7–9 nerved, usually glabrous, apex acute and keeled with sub-apical awn, straight, 0.5–3 mm long, palea (Fig. 3H) of the basal floret shorter than the length of the lemma, 0.7–1.3 cm long. Stamens 3. Caryopsis linear-lanceolate. Plants hexaploid, 2n=6x=42.
Phenology:— Flowering and fruiting occur from mid-October to the end of January.
Vernacular name:— “cebadilla de los médanos”, “sand dune brome”
Ecology and distribution:— Populations of the new species are distributed along 160 km of the coastline between the localities of Mar Chiquita (37°44’43.2” S, 57°25’10.7” W) and Quequén (38°33’44” S, 58°37’31.2”W). The species grows on alkaline soils (pH 8.2–8.6) with low organic matter content (0.7–2.4%), and sandy to loamy-sandy texture. It is commonly associated with the exotic species Carpobrotus edulis (Linnaeus 1759: 1060) N. E. Brown (1926: 249) and the native species Poa lanuginosa Poiret (1804: 91), Panicum racemosum (Palisot de Beauvois 1812: 168) Sprengel (1824: 313), Achyrocline saturejoides (Lamarck 1788: 747) Candolle (1838: 220), Calystegia soldanella (Linnaeus 1753: 159) Roemer & Schultes (1819: 184), Margyricarpus pinnatus (Lamarck 1785: 567) Kuntze (1898: 77), and Adesmia incana Vogel (1838: 76). It grows in sympatry with other species of the genus: B. catharticus var. catharticus, B. auleticus, and B. rigidus.
Etymology:— Dedicated to Botany Professor Sara Isabel Alonso, who encouraged us to investigate and describe this new species to science.
Additional material examined:— Argentina. Buenos Aires. Pdo. Gral Pueyrredón, Playa Escondida, 38°13’32”S, 57°43’27.6” W, 15 m a.s.l., 3 November 2019, M.L. Echeverría 201 (BAL 332); Ibidem, Pdo. Gral. Pueyrredón, Playa Chica, 38°1’22.4”S, 57°31’38.6”W, 15 m a.s.l., 7 November 2019, G.A. Leofanti 2 (BAL 358); Ibidem, Pdo. Mar Chiquita, La Caleta, 37° 46’ 52.3” S, 57° 27’ 12,5” W, 3 m a.s.l, 4 November 2019, M.L. Echeverría & G.A. Leofanti 228 (BAL 316); Ibidem, Pdo. Mar Chiquita, Mar Chiquita, 37°44’45.6”S, 57°25’10.6”W, - 3 m a.s.l, 4 November 2019, M.L. Echeverría & G.A. Leofanti 244 (BAL 371); Ibidem, Pdo. Necochea, Costa Bonita, 38°33’43.9”S, 58°37’31.4”W, 11 November 2019, M.L. Echeverría & G. Leofanti 258 (BAL 343); Ibidem, Pdo. Necochea, Quequén, 38°33’11.7”S, 58°40’23.9”W, 11 November 2019, M.L. Echeverría 270 & G.A. Leofanti 244 (BAL 390).
description: Published as part of Leofanti, Gabriela Agustina, Echeverría, María Lis & Méndez, Alicia López, 2024, A new species of Bromus sect. Ceratochloa (Poaceae: Bromeae) from Argentina, pp. 47-56 in Phytotaxa 669 (1) on pages 51-53, DOI: 10.11646/phytotaxa.669.1.5, http://zenodo.org/record/14519715