Chamaecrista amiciella (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 : 17-20

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

≡ Cassia amiciella Irwin & Barneby (1978: 267) .

Type:— BRAZIL. Bahia: Queimadas, 09 June 1915, Rose & Russell 19837 (holotype US00001393 ! , isotype NY00003708 !) .

( Figs. 5 and 6 )

Subshrubs, perennial, 10–50 cm tall, erect or decumbent. Root nodules unknown. Branches green-brown, non-striated, setulose-viscous and puberulent indumentum, including stipules, petiole and rachis; non-exfoliating bark. Stipules 0.5–2 × 0.3–0.4 mm, lanceolate and persistent.Leaves alternate-spiral, regularly distributed on the stem, plagiotropic; petiole 0.8–2.5 cm long; rachis 1.5–4 mm long; leaflets 2 pairs, 0.4–1.5 × 0.4–1.2 cm, of similar size, rhomboid or oblique-oboval, apex rounded or emarginate, mucronulate or not, base cuneate or oblique, papyraceous, concolorous, pubescent at least along the midrib on the abaxial face; margin entire, flat or sometimes revolute and ciliated; secondary veins 2–3 pairs, inconspicuous and imprinted on both sides. Leafy appendix inter-petioluleabsent. Racemes 4–12.5 cm long, peduncle 7–15 mm, 3–15 flowers, lax, terminal and apparently opposite the penultimate leaf, erect with straight or slightly sinuous axis, setulose-viscous and villosule, including pedicel, external face of the bracts, bracteoles and sepals. Bracts 0.6–1.5 × 1 mm, triangular, persistent. Bracteoles 0.3–0.7 × 0.5 mm, triangular or oval, persistent. Buds 4–5 × 3–4.5 mm, ovoid or globoid, apex obtuse. Flowers 1.2–2.8 × 1–2 cm; pedicel 0.8–1.5 cm long, straight and ascending, recurved and sinuous or not, when fruited; sepals 4.5–7.5 × 2–4 mm, elliptical, apex acute or obtuse, green or with vinaceous macules externally; 4 flat oboval petals and 1 inner falcate-curled petal encircling part of the stamens, 9–14 × 4–9 mm, yellow; stamens 10, 4–5 mm long, anthers not barbulate; ovary 2.5–3 × 1 mm, villosule; style 6–8.5 mm long, curved in upper third, glabrous.Legumes 2.5–3.5 × 0.3–0.4 cm, linear-oblong, puberulent and sparsely setulose-viscous, green-brown. Seeds 4–6, 5–7.3–3.5 × 2.2–2.5 mm, oblong, blackened.

Etymology: —The epithet “ amiciella ” is due to similarities of the species with those of the genus Amicia .

Geographical distribution and habitat:—Endemic species of the Brazilian Caatinga (northern portion of Bahia, Pernambuco and Paraíba states) (Fig. 37B). It is infrequent, inhabiting only the edges of vegetation on sandy soils or between rocks between 230 and 500 m altitude. In online databases (e.g. SpeciesLink; Flora e Funga do Brasil 2022) and in floristic studies in the Northeast region ( Queiroz 2009) several specimens of Ch. amiciella are recorded in the northeastern region and even in Goiás state, in the Center-West region. However, analyzing these, we concluded that most of these specimens are actually Ch. hispidula or Ch. fagonioides .

Flowering and fruiting:—It can be found with flowers and fruits from January to October, being more common between February and June.

Conservation status: — Chamaecrista amiciella had its Extension of Occurrence estimated at 112,240.82 km 2, which led us to classify it as Least Concern (LC) category. However, we emphasize that, in its area of occurrence, the species is infrequent and grows on the outskirts of areas of urban centers and disturbed places (e.g. roadsides) which compromises its conservation in the near future.

Taxonomic history: — Chamaecrista amiciella was described by Irwin & Barneby (1978) in the genus Cassia (= C. amiciella ) based on the Rose & Russell 19837 collection from the Caatinga in the municipality of Queimadas, state of Bahia, and allocated to the C. series Absoideae . The species was transferred to Chamaecrista by the same authors four years later ( Irwin & Barneby 1982), who maintained its specific status and systematic position. Finally, Souza et al. (2021) allocated the species to Ch. sect. Absus subsect. Absus .

Characterization and morphological relationships: — Chamaecrista amiciella is quite similar to Ch. hispidula , as they both share the decumbent subshrub habit, setulose-viscous branches, leaves with petioles 2.5–5 times longer than the rachis and short pedunculated racemes, which lead them to be frequently confused in herbarium collections. However, Ch. amiciella has leaflets that are usually rhomboid or oblique-oboval and ovoid or globoid buds with an obtuse apex, while Ch. hispidula has oboval, oboval-elliptic, oblong-elliptical or suborbicular leaflets and ovoid or ellipsoidal buds with an acute or apiculate apex.

Specimens examined:— BRAZIL. Bahia: Iaçu, Fazenda Santo Antônio, 12°48’25’’S, 40°05’51’’W, 280m, 05 February 2005, (fl., fr.), J . Paula-Souza et al. 5509 ( ESA); Iramaia, Ca. 3 km do Pé de Serra na estrada para Contendas do Sincorá , ramal a esquerda com 17 km de extensão, 09 April 1999, (fl.), S. C . de Sant’Ana 746 ( NY); Itaberaba, Fazenda Itaberaba, Morro Itibiraba , 12°30’05”S, 40°04’54”W, 230m, 04 June 2005, (fl.), E . Melo et al. 3898 ( HUEFS); ib., 12°30’04’’S, 40°04’59’’W, 23 October 2005, (fl., fr.), E . Melo et al. 4138 ( HUEFS); Itatim, Morro das Tocas , 91 km de Feira de Santana na BR 116 , 14 April 1995, (fr.), E . Melo & F . França 1175 ( CEN); ib., Morro das Tocas , 12°43’00”S, 39°42’00”W, 29 June 1996, (fl.), E . Melo 1609 ( IBGE); Queimadas , 5 km al SE de Queimadas, caminho à Serrinha, 15 January 1997, (fl., fr.), M. M . Arbo et al. 7266 ( NY); ib., BA-120 de Queimadas para Santa Luz , 11°01’31.1”S, 39°34’49.9”W, 326m, 08 August 2017, (fl., fr.), A. O . Souza 2226a, 2227a, 2228a ( UB, UFG) . Paraíba: Patos, ás margens da BR , 25 March 1993, (fl., fr.), M. F . Agra 1734 ( NY) . Pernambuco: Petrolina, nordeste entre Rajada e Dormentes, km 6, 07 April 1979, (fl.), L . Coradin 1340 ( CEN, EAC, NY); Salgueiro , área do PISF, VPR Queimada Grande, Faz. Miguel, entrada à direita na estrada para Umãs; ca. 6km NE de Salgueiro , 08°02’56.5”S, 39°10’34.7”W, 476m, 09 February 2009, (fl.), J. G . Carvalho-Sobrinho et al. 1902 ( UFRN); Triunfo , 02 July 1979, (fl.), A . Fernandes & Matos s. n. ( EAC0006662 ); ib., 30 May 1982, (fl., fr.), A . Fernandes & Matos s. n. ( EAC0011690 ) .

Figures

FIGURE 5. Chamaecrista amiciella. A. Habit, B. Branches, C. Flowered branch, D. Fructified branches, E. and F. Leaves, G. Buds, H. Flower, I. Fruit. Photographs by A.O. Souza.

FIGURE 6. Chamaecrista amiciella. A. Fertile branch, B. Detail of branch indumentum, C. Leaf, D. Leaflet, E. Detail of the abaxial face of leaflet, F. Bud, G. Flower, H. Sepal, I. Petals, J. Stamen, K. Gynoecium, L. Fruit.Drawned by Renato Galhardo.