Gymnopogon doellii Boechat & Valls (1990: 314)

Vinícius-Silva, Ronaldo, Paula, Cláudio Coelho De & Saraiva, Diogo Felcar, 2020, New records of Gymnopogon doellii (Poaceae, Chloridoideae, Cynodonteae, Hubbardochloinae), a Brazilian endangered species, Phytotaxa 435 (1), pp. 57-62 : 58-61

Gymnopogon doellii Boechat & Valls (1990: 314) , Figs. 2 , 3

Type:— BRAZIL. Federal District (‘Distrito Federal’): Brasília, Environmental Protection Area of the São Bartolomeu River Basin, ca. 5 km S of the site where the dam of the future lake will be constructed, in the dry bed of a temporary stream, 6 June 1989, T. S. Filgueiras & S. P. Araújo 1803 (holotype CEN 12341 image!).

Plants perennial, rhizomatous, rhizomes 1 cm long, short and thick; culms 20–100 cm long, 2–6 mm diam.; internodes yellow, minutely striated, glabrous. Leaves 8–16, distichous; leaf sheaths longer than the internodes, striated, vinaceous, glabrous; ligules 0.2–0.3 mm long, membranous-ciliate. Leaf blades 5–12 × 0.5–1.7 cm, subcordate, longitudinally striated on both surfaces, midvein inconspicuous, glabrous on both surfaces, apex acute and acuminate; base narrow, constituting a structure similar to a collar. Inflorescence 15–40 cm, with 10–30 spiciform racemes, racemes 5–22 cm long. Spikelets fusiform, short-pedicelled, laterally compressed, 5–10 mm long, 1-flowered, appressed to the rachis, arranged in two alternate series. Glumes 2; subequal, lower glume 5–9 mm long, longer than the floret, glabrous, muticous; upper glume 5.2–10 mm long, longer than the floret, membranous, 1-nerved, scabrous near the vein and glabrous elsewhere, muticous. Lemma 2–3.5 mm long, membranous, 3-nerved, sparsely pilose, awned, awn 5–13 mm long. Palea 2–3 mm long, membranous, 2-nerved, glabrous, scabrous towards the veins and apex. Rachilla extension 1–2 mm long, with inconspicuous floret at the apex, floret with lemma 0.5–1.5 mm long, awned, awn 2–7.5 mm long. Caryopsis ca. 2.5–3 mm long, fusiform.

Comments:— Gymnopogon doellii can be distinguished from other species of the genus by the presence of short rhizomes, indistinct leaf blade midvein, ligule with a fringe of hairs and acuminate glumes twice the floret size ( Cialdella and Zuloaga 2011). The most similar species to G. doellii is G. spicatus ( Sprengel 1825: 243) Kuntze (1898: 354) due to its size and habit, being distinguished by the absence in the latter of a pseudoligular ring of hairs and of muticous glumes. Additionally, G. doellii has a restricted geographical distribution, occurring only in Brazil (Minas Gerais and Goiás states and Federal District), whereas G. spicatus is widely distributed in Brazil and has its occurrence extended to Argentina, Uruguay, Paraguay, Peru, Bolivia, Venezuela, Colombia, Guatemala, Belize, Mexico and USA ( Cialdella and Zuloaga 2011). Gymnopogon doellii also resembles G. ambiguus ( Michaux 1805: 58) Britton, Sterns & Poggenburg (1888: 69) , being distinguished by its longer glumes and shorter lemma. Furthermore, G. ambiguus does not occur in Brazil; it is distributed from southern USA to the Caribbean, where it has been reported from Haiti and the Dominican Republic ( Boechat and Valls 1990 a, Cialdella and Zuloaga 2011).

Distribution and habitat:— The new records reported here expand the distribution of G. doellii in Brazil, particularly in Minas Gerais state. The species had been previously reported only from Cerrado regions (Brasília at Federal District, Alexânia at Goiás state and Lagoa Santa at Minas Gerais state), while the new collections reported here were made in areas of Ferruginous Campos Rupestres (rocky outcrops) at Minas Gerais (Itabirito and Rio Acima cities) ( Fig. 1 ). These areas are characterized by having dry, sandy soils, which are preferable substrates for the establishment of most Gymnopogon species ( Cialdella and Zuloaga 2011). The Campos Rupestres form an ecosystem with remarkable diversity, including rare species (such as G. doelli ) and endemic species. However, it is currently threatened by anthropic actions such as mining activity ( Silveira et al. 2016).

Phenology:— The species was collected with flowers/fruits from January to June.

Conservation:— Gymnopogon doellii is considered Critically Endangered (CR) in the Red Book of Brazilian Flora ( Martinelli & Moraes 2013), according to IUCN criteria (B1ab(iii)). Studies on G. doellii were already scarce over 20 years ago, and since then only a few more studies have been conducted ( Boechat and Valls 1990b, Carmona et al. 1997, Martins et al. 1997). Such scarcity in the literature reveals the need to perform further studies on the species, especially ones that will provide guidelines for the species conservation.

The extent of occurrence (EOO) and area of occupancy (AOO) of G. doellii calculated with GeoCAT ( Bachman et al. 2011) were 62,456.720 km 2 and 32.000 km 2, respectively. Following the IUCN Red List Categories and Criteria ( IUCN 2017), G. doellii fits the Endangered (EN) status. In that sense, increasing collection efforts in order to sample new populations is imperative to allow for the successful performance of genetic, ecological, molecular and in-vitro cultivation studies on G. doellii , so that effective measures for the species conservation can be formulated.

New records: BRAZIL: Minas Gerais, Itabirito , 20°25’33” S, 43°55’36” W, 28 January 2015, A. E. Brina s.n. ( BHCB181849 ) ; ibidem, Aredes Ecological Station, near the Station , 20°18’12” S, 43°54’36” W, 31 January 2013, P. B. Meyer & M. S. Mendes 3001 ( BHCB) ; ibidem, Serrinhas Mountain Range, near the Aredes Ecological Station, Moeda Syncline , 20°30’38” S, 44°31’00” W, 09 March 2017, P. B. Meyer & N. L. Paula 3029 ( BHCB) ; Rio Acima, Retiro José Pereira Farm, farm owned by Vale S. A., 20°07’37” S, 43°44’45” W, 23 January 2018, P. B. Meyer, A. E. Brina & M. S. Mendes 3127 ( BHCB) .

Figures

FIGURE 1. Geographic distribution of Gymnopogon doellii, including new and old records.

FIGURE 2. Gymnopogon doellii. A. Rhizome and a section of the culm. B. Culm apical region, with detail of leaves. C. Individual at vegetative stage. D. Flowering individual, with inflorescence at early stage of development. E. Flowering individual, with inflorescence at advanced stage of development. F. Flowering individual, with fully developed inflorescence. (Photographs by Ronaldo Vinícius-Silva taken at Estacão Ecológica Arêdes, Itabirito City, Minas Gerais state).

FIGURE 3. Gymnopogon doellii. (Brina E.A. s.n. BHCB181849). A. Rhizome with roots and a section of the culm. B. Mature flowering individual.C. Ligular region. D. A section of the inflorescence. E. Spikelet.F. Lower glume. G. Upper glume. H. Lemma. I. Palea; adaxial surface (left) and abaxial surface with rachilla extension, which has a rudimentary floret with an awned lemma (right). J. Gynoecium and androecium. K. Caryopsis. (Illustration by Reinaldo Pinto).