Chamaecrista longistyla Souza &Silva In Souza et al. (2019: 302)

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 : 59-62

14. Chamaecrista longistyla Souza &Silva In Souza et al. (2019: 302) . Type:— BRAZIL. Mato Grosso: Novo Mundo, Parque Estadual Cristalino , s. dat., (fl., fr.), Sasaki, D. 1605 (holotype UFG!; isotype HERBAN!). (Figs. 27 and 28)

Subshrubs perennial, 1.5–1.7 m tall, erect, little or not branched. Root nodules absent. Branches yellow-green when young and brown when adults, both hispid-viscous and puberulent including stipules, petiole and rachis; non-exfoliating bark. Stipules 4–5 × 0.4–0.5 mm, lanceolate, persistent.Leaves alternatespiral,regularly distributed along the stem, plagiotropic; petiole 4–5 cm long; rachis 1.4–1.8 cm long; leaflets 2 pairs, 3–5.4 × 2.6–4.1 cm, distal pair slightly larger than proximal pair, oval, largely elliptical or suborbicular, apex slightly emarginate or rounded and mucronate, base rounded or oblique in pair distal, membranous or papyraceous, concolorous, light green, puberulent on both sides and setulose-viscous along the main vein on the abaxial side; margin entire, flat or sometimes slightly revolute, ciliate; secondary veins 6–9 pairs, conspicuous and slightly prominent on both sides. Leafy appendix inter-petiolule absent. Racemes 10.3–25.5 cm long, 10–18 flowers, terminal, sessile, lax, erect, straight axis, setulose-viscous and puberulent, including pedicel, external surface of bracts, bracteoles and sepals. Bracts 3–3.5 × 0.4–1 mm, lanceolate, persistent. Bracts 1–1.5 × 0.5 mm, similar to bracts. Buds 1–1.2 × 0.6–0.9 cm, ellipsoid, apex obtuse. Flowers 3.5–4 × 2.8–3 cm; pedicel 1.5–1.7 cm long. straight, abruptly curved down when fruited; sepals 1.2–1.3 × 5 mm, elliptical or oblongelliptic, apex obtuse, externally yellowish-green; 4 flat petals, 3 oboval, 2–2.5 × 1.1–1.6 cm and one broadly oboval 2–2.3 cm wide and 1 falcate-curled inner petal; stamens 10, 6–8 mm long, anthers not barbulate; ovary 3.5–4 × 1.8 mm, densely setulose and puberulent; style 2–2.2 cm long, curved in upper third, glabrous. Legumes 6–6.5 × 0.7–0.8 cm, linear-oblong, setose-viscous and puberulent, light brown, probably with 6–8 seeds. Seeds not seen.

Etymology: —in reference to the long stylet (longi =long, styla (“ stylus ”) = style).

Geographical distribution and habitat:—Species known so far from the municipality of Novo Mundo, state of Mato Grosso, Brazil, and the city of Huacaraje in Bolivia (Fig. 39A), where it grows in open areas of cerrado in the middle of the Amazon Domain on latosols between 331 and 500 meters altitude.

Flowering and fruiting:—species, until then, registered with flowers and fruits between March and April.

Conservation status: —In view of the few collection records we have of this species, we prefer to classify it in the Insufficient Data (DD) category.

Taxonomic history:— Chamaecrista longistyla was described as new during this study and allocated to Ch. sect. subsect Absus ser. Absoideae ( Souza et al. 2019) due to 4-foliolate leaves with long petioles, membranous leaflets and typical racemes. However, it was transferred to Ch. sect. Absus subsect. Absus , based on the phylogenetic relationships observed by Souza et al. (2021).

Characterization and morphological relationships: — Chamaecrista longistyla is an erect subshrub up to 1.7 m tall, few or not branched, has leaflets 3–5.4 cm long, oval, largely elliptical or suborbicular, concolor with a flat margin and membranous or papyraceous, flowers with long styles (2– 2.2 cm long) and usually distally curved, pedicel abruptly curved down when fruited, and legumes 6–6.5 cm long. These characteristics, together, make Ch. longistyla unmistakable with the other species of subsection Absus .

Specimens examined:— BRAZIL. Mato Grosso: Novo Mundo, RPPN Cristalino Serra 1, 9º21’04”S, 55º33’00”W, 331 m, 29 March 2017 (fl., fr.), D. R . Silva 163 ( HERBAN) . BOLIVIA. El Beni: prov. Itenez, Huacaraje , 13º31’S, 63º45’W, 11 April 1979, (fl.), A . Krapovickas & A . Schinini 34850 ( NY) .