Chamaecrista chapadae (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 : 37-40

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

≡ Cassia chapadae Irwin & Barneby (1978: 258) .

Type:— BRAZIL. Bahia: Iraquara, Serra da Água de Rega , ± 26km North of Seabra road to Água de Rega , near Rio Riachão , ± 1000m, 23 November 1971, (fl.), H.S.Irwin, Harley & G.L. Smith 30798 (holotype UB0037179 ! , isotypes C10011952 !, F0057554F !, GH00053149 !, K000056408 !, LE00006826 !, NY00003754 !, NY00003755 !, RB00545349 !, RB00539445 !, S-R-8794 !, UC1418643 !, US00001415 !) . (Figs. 17 and 18)

Subshrubs perennial, 30–50 cm tall, erect, cespitose. Root nodules absent. Branches blackish or brown when young, villosule and setulose-viscous, including stipules, petiole and rachis; non-exfoliating bark. Stipules 2–3 × 0.4–0.5 mm, lanceolate, persistent. Leaves alternate spiral, distributed above the middle of the stem, plagiotropic; petiole 0.5–1.1 cm long; rachis 0.4–1 cm long; leaflets 2 pairs, 0.6–2 × 0.5–1.3 cm, distal pair slightly asymmetrical and larger than proximal pair, obcordate or spatulate, apex emarginate or rounded, base asymmetrical, chartaceous to papyraceous, discolored, green-dark, glossy and glabrous or puberulent on the adaxial surface, opaque green, pubescent and setulose-viscous on the abaxial surface; margin entire, revolute and ciliate; secondary veins 4–5 pairs, inconspicuous and imprinted on both sides. Leafy appendix inter-petioluleabsent. Racemes 2.5–6 cm long, sessile, 4–15 flowers, congested, terminal, erect with straight axis, setulose-viscous and villous, including pedicel, external surface of bracts, bracteoles and sepals. Bracts 4–5 × 0.4–1 mm, lanceolate, persistent. Bracteoles 2–3 × 0.5 mm, lanceolate, persistent. Buds 0.8–1 × 0.6–0.7 cm, ellipsoid, apex obtuse and apiculate. Flowers 1.5–2.5 × 1.5–2.5 cm; pedicel 0.8–1.8 cm long, straight and ascending even when fruited; sepals 1–1.2 × 0.3–0.4 mm, elliptical, apex acute, yellow-reddish externally; 4 flat, oboval or spatulate petals and 1 falcate-curled inner petal, 1.2–1.5 × 0.8–1.2 cm, yellow; stamens 10, 3–4 mm long, anthers not barbulate; ovary 2.5–3 × 1.5 mm, setulose-viscous and puberulent; style 8–8.5 mm 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, 3–4 × 3.2–4 mm, obovoid, blackish.

Etymology: —epithet in reference to Chapada Diamantina, place of occurrence of the species.

Geographical distribution and habitat:—Endemic species from Chapada Diamantina, state of Bahia, where it is recorded in the municipalities of Mucugê and Lençóis (Fig. 38B), forming expressive populations (more than 20 mature individuals) growing in sandy soils, rock outcrops, from flat areas to slopes of hills in rupestrian fields between 900–1480 m altitude, where it stands out for the conspicuous appearance of clumps.

Flowering and fruiting:—collected with flowers from February to November, both being more abundant from May to September.

Conservation status: — Chamaecrista chapadae has its Extension of Occurrence estimated at 1,265.35 km 2, which allows us to classify it in the Endangered category (EN), criteria B (bi, iii, iv) and C. However, it grows in areas of difficult access (slopes of hills and rock outcrops), some of which are protected by law such as the Chapada Diamantina National Park, one of the main Conservation Units in the country.

Taxonomic history:—Species with a simple taxonomic history, as it was described by Irwin & Barneby in 1978 under the name Cassia chapadae and transferred to the genus Chamaecrista by the same authors in 1982.

Characterization and morphological relationships: — Chamaecrista chapadae is easily recognizable by its subshrub with caespitose growth and by its discolored, obcordate or spatulate leaflets with an emarginate apex and a conspicuously revolute margin. Share with Ch. jacobinae the growth aspect, the discolored leaflets and, in part, the same area of occurrence. However, Ch. jacobinae have elliptical, oblong-elliptic or oboval leaflets with an obtuse or rounded apex and a flat or revolute margin near the base or apex; lax racemes (vs. congested in Ch. chapadae ), buds with acuminate apex (vs. obtuse) and occurs in the northern portion of Chapada Diamantina around Jacobina and Morro do Chapéu.

Specimens examined:— BRAZIL. Bahia: Abaíra, Cabeceira Riacho Fundo, atrás da Serra do Bicota , 13º23’00”S, 41º51’00”W, 1480m, 25 October 1993, (fr.), W . Ganev 2305 ( UB); Ibicoara, Chapada Diamantina, Serra do Sincorá, 13°23’S, 41°13’’ W , 1000m, 18 July 2001, (fl., fr.), M . Araújo-Nóbrega 354 ( SPF, UEC); Lençóis, entre Lençóis e Palmeiras , 900m, 14 September 1956, (fl.), E . Pereira 2038 ( F, IAC, UB); ib., Morro do Pai Inácio, junto a Torre de transmissão, 17 July 1982, (fl.), A. C . Sarmento 672 ( CEN); ib., na base do Morro do Pai Inácio , ca, 26 km W da cidade, 1000m, 18 July 1985, (fl.), T. M . Cerati et al. 297 ( SP); Mucugê , 4 km S . of Mucugê, on road from Cascavel by the Rio Cumbuca , 13°00’00’’S, 41°23’00’’W, 900m, 06 February 1974, (fl.), R. M . Harley 16044 ( L / U, NY); ib., margem da estrada Andaraí-Mucugê, estrada nova, a 13 km de Mucugê , próximo a uma grande pedreira na margem esquerda, 21 July 1981, (fl., fr.), J. R . Pirani et al. s. n. ( UEC1355699 ); ib., Serra do Pina along Rio Preto NW of Mucugê, 900m, 23 July 1983, (fl., fr.), R . Kral et al. 72913 ( SP); ib., rodovia-Mucugê – Andaraí km 9, 12º55’S, 41º21’W, 1050m, 06 September 1994, (fr.), G. P . Silva et al. 2669 ( CEN); ib., Parque Nacional da Chapada Diamantina, Gerais do rio Preto , 12°46’00’’S, 41°28’00’’W, 1336m, 19 June 2005, (fl.), D. Cardoso & A. A . Conceição 596 ( NY); ib., sopé do morro próximo as residências a W de Mucugê , 11 May 2017, (fl., fr.), A. O . Souza et al. 2062, 2063, 2064 ( UB, UFG); ib., ca. 1 km ao sul de Mucugê em direção a BA-265 na estrada de chão a direita, 12°59’39.7”S, 41°23’1.5”W, 988m, 12 May 2017, (fl., fr.), A. O . Souza et al. 2069 ( UB, UFG); Palmeiras , Serras dos Lençóis, middle and upper slopes of Pai Inácio ca. 15km N. W . of Lençóis, just N . of the main Seabra-Itaberaba road, 12°27’S, 41°28’W, 1000m, 24May 1980, (fl.), R. M . Harley 22517 ( L / U, NY, UEC); ib., Morro da Mãe Inácia , 12°27’00’’S, 14°28’00’’W, 07 September 2005, (fl., fr.), C. O . Cerqueira 12 ( HUEFS) .