Chamaecrista roncadorensis (H.S. Irwin & Barneby) Irwin & Barneby (1982: 661)

Souza, Alessandro Oliveira De, Cavalcante, Raphael Guarda & Silva, Marcos José Da, 2022, Taxonomic revision of Chamaecrista sect. Absus subsect. Absus (Leguminosae, Caesalpinioideae) with adjustments in the new classification, Phytotaxa 565 (1), pp. 1-82 : 70-73

publication ID 10.11646/phytotaxa.565.1.1

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Chamaecrista roncadorensis (H.S. Irwin & Barneby) Irwin & Barneby (1982: 661)


17. Chamaecrista roncadorensis (H.S. Irwin & Barneby) Irwin & Barneby (1982: 661) Cassia roncadorensis Irwin & Barneby (1978: 272) . Type:— BRAZIL. Mato Grosso: Xavatina, Serra do Roncador, at Rio Turvo, ± 210 km. N. of Xavantlna, 28 May 1966, H.S. Irwin, Grear, Souza, & Reis dos Santos 16170 (holotype UB31578!, isotypes F0057663F!, GH00053295!, K000555603!, NY00003895!, NY00003896!, RB00545322!, RB00539489!, S-R-8855!, US 00001685!). (Figs. 33 and 34)

Subshrubs evergreen, decumbent or creeping, often with adventitious roots emerging from leaf nodes, diffuse growth and branching from the base. Root nodules absent. Branches brown or yellowish, glabrous; non-exfoliating bark. Stipules 2–3 × 0.4–0.5 mm, lanceolate, persistent.Leaves alternate spiral,regularly distributed along the stem, oriented opposite the ground; petiole 1–1.7 cm long; rachis 0.8–1.3 cm long; leaflets 2 pairs, 2–4 × 1–2 cm, distal pair slightly larger than proximal pair, elliptical or oval-elliptic, apex obtuse and mucronate, base obtuse or slightly oblique on distal pair, chartaceous, concolor, opaque green or with vinaceous tones on both sides, glabrous, margin entire, flat and not ciliated; secondary veins 4–7 pairs, conspicuous and slightly prominent on abaxial surface. Leafy appendix inter-petiolule absent. Racemes 6.5–14 cm long, sessile, the preceding leaf may be deciduous, 8–15 flowers, lax or congested, terminal, suberect, ascending recurved axis, setulose-viscous and puberulent, including pedicel, external surface of the bracts, bracteoles and sepals. Bracts 2–2.5 × 0.4–1 mm, lanceolate, persistent. Bracts 1–1.5 × 0.5 mm, similar to bracts. Buds 5–10 × 4–6 mm, ellipsoid, apex obtuse.Flowers 4.5–5 × 1–1.8 cm; pedicel 2.5–4 cm long, straight and ascending even when fruited; sepals 10–15 × 5–7 mm, elliptical or oblong-elliptic, apex obtuse or acute, yellow with vinous tones externally; 4 flat oboval petals and 1 falcate-curled inner petal, 2–2.3 × 1.4–1.8 cm, yellow; stamens 10, 6–8 mm long, anthers not barbulate; ovary 2.5–3 × 1.5 mm, setulose-viscous and villous; style 1–1.2 cm long, curved in upper third, glabrous. Legumes 2.5–3 × 0.7–0.9 cm, linear-oblong, setulose-viscous and sparsely puberulent, dark brown. Seeds 4–6, 4–6.5 × 4–5.5 mm, obovoid, blackened.

Etymology: —in reference to the place of origin of the type collection, Serra do Roncador in the state of Mato Grosso.

Geographical distribution and habitat:— Chamaecrista roncadorensis it occurs in the east-northeast portion of Mato Grosso and in the northeast of Goiás on the border with Bahia, being the first recorded for the latter state here (Fig. 39D). It grows in typical cerrado or cerrado ralo in sandy or sandy clay soils at altitudes between 700 and 800 meters.

Flowering and fruiting:—collected with flowers mainly between May and August, but also blooms in December.

Conservation status: —Species with conservation of Least Concern (LC) as it has an Occurrence Extension greater than 50,000 km 2. Despite this, it seems infrequent where it occurs, forms populations with few individuals and grows close to houses and in places whose vegetation has been constantly removed for the implementation of agriculture.

Taxonomic history:— Irwin & Barneby (1978) described C. roncadorensis as one of 24 species of C. sect. Absus subsect. Absus ser. Absoideae , in 1982 it was transferred to Chamaecrista by the same authors and Souza et al. (2021) placed it in the subsect. abs.

Characterization and morphological relationships: —Chamaecristaroncadorensis can be recognized by its decumbent (up to 8 cm above ground) or creeping habit with stolon-like growth, in addition it has yellowish-brown stems and branches and usually glabrous and non-exfoliating, glossy green leaves oriented upwards and suberect racemes, the which makes it easily recognizable. It resembles Ch. juruenensis by the general shape of the leaves, inflorescences and flowers, in addition to the main vein highlighted on the abaxial face. However, the latter, reaching 1.5–3 m tall, has a subshrub or upright shrub habit, often covered by a dense villosule indumentum with white, nonviscous trichomes, including leaves, woody branches and leaves.

Specimens examined:— BRAZIL. Bahia: Cocos, Fazenda Trinjunção , 14°52’50”S, 46°02’48”W, 840m, 15 May 2001, (fl.), M. L GoogleMaps . Fonseca et al. 2681 ( IBGE, NY); Correntina, Velha da Galinha , 2 km da Fazenda Guaratã, 13°32’25”S, 45°24’25”W, 718m, 26 August 1995, (fl.), R. C GoogleMaps . Mendonça et al. 2377 ( NY) . Goiás: Posse, BR-020 a 4 km sul do entroncamento da estrada Posse / Brasília , 17 August 1990, (fl., fr.), T. B . Cavalcanti et al. 760, 764 ( CEN, NY, SP); ib., Na entrada da cidade de Posse, cerrado próximo aos loteamento no começo da cidade, 14°06’16.1”S, 46°19’54.4”W, 854m, 11 July 2014, (fl., fr.), A. O GoogleMaps . Souza et al. 1207, 1208, 1209 ( UB, UFG); ib., ca. 1 km ao norte do Trevo da entrada da cidade de Posse, lado esquerdo da rodovia, 14°06’36.7”S, 46°18’25.5”W, 822m, 08 May 2017, (fl., fr.), A. O GoogleMaps . Souza & L. L. C . Antunes 2040, 2041, 2042, 2043 ( UB, UFG); ib., ca. 10 km ao norte de Posse na BR-020 km 241, 14°02’13.5”S, 46°15’17.5”W, 834m, 15 December 2017, (fr.), A. O GoogleMaps . Souza et al. 2223b ( UB); São Domingos, Serra S . Domingos , 21 May 1983, (fl.), J. A . Rizzo & H . D. Ferreira 10299 ( UFG) . Mato Grosso: Nova Xavantina, rio Turvo , ca. 210 km N of Xavantina, 500m, 28 May 1966, (fl.), H. S . Irwin et al. 16155 ( NY) .


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