Chamaecrista orbiculata ( Bentham 1840: 79 ) Irwin & Barneby (1982: 655)

Mendes, Thainara Policarpo, Souza, Alessandro Oliveira De & Silva, Marcos José Da, 2021, Taxonomic review of Chamaecrista sect. Absus subsect. Absus ser. Paniculatae (Benth.) H. S. Irwin & Barneby (Leguminosae, Caesalpinioideae), Phytotaxa 495 (1), pp. 1-64 : 36-42

7. Chamaecrista orbiculata ( Bentham 1840: 79) Irwin & Barneby (1982: 655) . ≡ Cassia orbiculata Bentham (1840: 79) . Type: — BRAZIL. Minas Gerais: Cachoeiras do Campos, 1839, P. Claussen 167 (lectotype: K! [K000555584], designated here, photo IPA! [1043], NY! [1490]; isolectotype: G! [00371000], F! [1022344], photo F! [53979]). Figs. 22 and 23

Small trees 0.7–2.5 m tall, or shrubs 20–90 cm tall, erects. Tortuous stems with bark longitudinally fissured, dark brown or greyish. Branches cylindrical, erect or pendent, adult branches with bark longitudinally fissured, dark brown or greyish, young branches discreetly fissured longitudinally, light brown, viscous-setulose, including petiole, margin of leaflets, axis of inflorescence, pedicel, external surface of stipules, bracts, bracteoles, buds, sepals, ovary and fruits. Stipules 1.8−6.8 mm long, linear-subulate, persistent. Leaves 5.9–13.5 cm long, distributed in the branch terminations or regularly distributed in the branch, ascending; pulvinus 2–6 mm long, visibly dilated, not striated; petiole 3.2−7.8 cm long; cylindrical and sulcate above or not; rachis 1.1–6.5 cm long, cylindrical and sulcate above or not; interfoliolar segments 1.8–2.3 cm long; pulvinule 1.1–4 mm long; visibly dilated; leaflets 2–4 pairs, coriaceous; blades 3–7.1 × 2.3–7.1 cm, orbicular or suborbicular, margin entire, corneously incrassate, surface abaxial and adaxial glabrous, base asymmetrically rounded, apex rounded or obtuse, with mucron or not, light green, opaque. venation with, secondary veins 5–13 pairs, yellow or light green. Panicles 22–36 cm long, with 3–10 secondary axis, not geminate, terminal or axillary, with flowers laxly distributed, erects. Bracts 0.8–3 × 0.2–1 mm, lanceolate, apex acute, margin entire, yellow or green with purplish pigmentation, persistent. Bracteoles 1–2.8 × 0.1–1 mm, lanceolate or deltoid, apex acute, margin entire, vinaceous, yellowish, or light brown, persistent. Buds 0.7–1.5 cm long, ovoid or ellipsoid, with base truncate, green with purplish pigmentation, apex obtuse. Flowers 4.5–6.6 cm long; pedicel 1.1–2.4 cm long, robust, cylindrical; sepals 1.4–1.8 × 0.5–0.7 cm, elliptic or oval-elliptical, apex acute or obtuse light green with purplish pigmentation; petals 0.8–3.5 × 1.5–3.9 cm obovate, with the adaxial petal like a standard, one of the inner petals coiled in the androecium; stamens 0.5–1.5 cm long, filaments 1–2 mm, long; anthers 0.6–1 cm long, mucronulate at apex or not. Ovary 3–6.1 × 1–1.2 mm; styles 0.9–1.8 cm long, pubescent. Legume 2.2–6.4 × 0.4–0.8 cm, green to vinaceous, pubescent, rarely with setulose and carthaceous margin, narrow-oblong. Seeds 6–7 × 3–3.8 mm, obovoid, light brown, smooth, glossy.

Representative specimens examined: BRAZIL. Bahia: Correntina, Fazenda jatobá, 07 August 1993, (fl.), F . França , T . S . filgueiras & M. A . Silva 756 ( HUEFS); ib., Velha da Galinha , trecho entre o aeroporto e a entrada para o bar estrela Galdina, 13°36’31’’S, 45°22’58’’W, 24 August 1995, (fl.), R . C . Mendonça , M . L . Fonseca & M . Aurélio Silva 2333 ( NY); ib., reserva biológica Fazenda Jatobá, 13°59’27.9’’S, 45°59’24.4’’W, 28 July 2004, (fl.), M . L . Fonseca, 5586 ( EAC, UEC); Palmas de Monte Alto , 14°26’82’’S, 43°15’94’’W, 14 April 2008, (fl.), E . P . Queiroz 3298 ( HRD); Rio das Contas, Próximo a capela de Bom Jesus, 13°34’09’’S, 41°48’19’’W, 1096 m, 29 July 2006, (fl., fr.), Harley , R . M , 55481 ( ESA). Federal District: Brasília, Cerrado próximo ao CPAC , sentido Sobradinho-Planaltina-DF, 03 July 1981, L . Coradin , A . G . Fernandes 4251, 4255 ( ESA); ib., Parque Nacional de Brasília , 15°43’S, 48°00’W, 06 May 1979, (fl.), J . G . Guimarães , 598 ( MO). ib., ca. 1.5 km W de antenas de Radiobrás , 15°36’00”S, 48°07’48”W, 14 April 1982, (fl.), J . H . Kirkbride Jr. 4718 ( NY): 2 km ao Norte do Córrego Sítio Novo , 13 June 1983, J . H . Kirkbride, Jr. 5336 ( NY) . Goiás: Alto Paraíso de Goiás, Chapada dos Veadeiros, 09 June 1972, (fl.), J . A . Rizzo 8125 ( ESA, UFG); ib., 08 July 1972, (fl.), J . A . Rizzo 8174 ( ESA, UFG); ib., 10 October 1972, (fl.), Rizzo 8393 ( ESA, UFG); ib., 12 km de Alto Paraíso de Goiás, em direção a Teresina de Goiás, 14°02’S, 40°29’W, 25 May 1994, (fl.), S . Bridgewater, et al. 195 ( ESA); Amorinopólis, Serra dos Caiapós à 40 km de Amorinópolis para Rio Verde , 17 April 1971, (fl.), J . A . Rizzo & A . Barbosa 6210 ( ESA, UFG); ib., 15 May 1971, (fl.), J . A . Rizzo 6306 ( ESA, UFG); ib., 20 July 1971, (fl.), J . A . Rizzo 6535 ( ESA); Cabeceiras de Goiás, km 1.5 da estrada Br-020 para Cabeceiras de Goiás, 15°20’S, 47°15’W, 01 May 1996, (fl.), B . A . S. Pereira & D. Alvarenga 3051 ( EAC, IBGE); Campo Alegre de Goiás, BR-050, 5–8 km S trevo para Ipameri , 11 June 1993, (fl.), G . Hatschbach , M . Hatschbach & E . Barbosa 59275 ( MBM, UPCB); ib., Cerca de 5 km de Campo Alegre de Goiás em direção a cristalina, 17°32’25’’S, 47°49’46’’W, 922 m, 08 April 1998, (fl.), V . C . Souza et al 21304 ( ESA); Cavalcante, Chapada dos Veadeiros, Ca. 6km a partir da Fazenda Papuã em direção a RPPN Serra do Tombador , 13°36’09’’S, 47°38’44’’W 1077 m, 03 July 2015, (fl., fr.), M . J . Silva et al. 6844 ( UFG), 6845 ( UFG), 6846 ( UFG), 6847 ( UFG), 6848 ( UFG), 6850 ( UFG), 6851 ( UFG), 6852 ( UFG), 6854 ( UFG), 6855 ( UFG), 6860 ( UFG); Cristalina, Linda Serra dos Topázios, 16°45’S, 47°40’W, 23 February 1998, (fl.), C . Proença , A . P . Silva & J . F . Ribeiro 1959 ( UB); Formosa, Fazenda J . Teles, Ca. 10 km norte NW de Formosa-Goiás, 850 m, 29 April 1966, (fl.), H . S . Irwin , R . Souza , J . W . Grear et al 1549 ( NY, EAC); Mambaí, SD-23-Y-B. Bacia do Rio Tocantins, Estrada da cidade de Mambaí para o Chapadão do Oeste da Bahia, 14°28’24’’S, 46°01’35’’W, 870m, 01 October 2009, (fl., fr.), B . A . S Pereira & D. Alvarenga 3601 ( IBGE, UEC); Niquelândia, Km 5 da estrada de asfalto de Niquelândia para Macedo cerrado, 14°25’27’’S, 48°26’09’’W, 28 February 1996, (fl.), M . L . Fonseca & B . S . Barros 795 ( NY); ib., 1 Km da Mina de Níquel passando por baixo do Teleférico, Lado esquerdo, 14°20’12’’S, 48°23’54’’W, 14 August 1996, (fl.), M . L . Fonseca et al. 1097 ( EAC); Pirenópolis, Alto da Serra Pireneus , na base dos Três Picos, 09 July 1971, (fl.), J . A . Rizzo 6493 ( ESA, UFG); Teresina de Goiás, Fazenda Hotel Ecológico Alpes Goianos, Rod. GO-118, km 202, 13°53’59.1’’S, 47°23’48.9’’W, 31 July 2000, (fl.), V . C . Souza et al. 24732 ( ESA); Vila Boa de Goiás, a esquerda do ribeirão Dourado próximo a sua cabeceira, 03 June 1968, (fl.), J . A . Rizzo 1123 ( ESA, UFG) . Mato Grosso: Rio verde, Rodovia Campo Grande-Cuiabá , G . Hatschbach et al. 31942 ( MBM) . Mato Grosso do Sul: Sonora, Rod , BR-165, km 211, 03 May 1995, G . Hatschbach et al. 62172 ( MO) . Minas Gerais: Bocaiúva, Min. Sada. Chapada da Zoeira , July 1993, L . V . Costa s.n. ( BHCB, NY); Coração de Jabotim , called invernada, 70km de Arinos pela rodovia Vila dos Gaúchos, 15°28’S, 45°47’, 900 m, 05 August 1998, (fl.), J . A . Ratter , S . Bridgewater & J . B . Santos 8070 ( INPA); ib., 48493 ( BHCB); Cristalina, Morro do Chapéu , 18°43’28’’S, 42°55’40’’W, 1146 m, 5 July 2007, F . Scheft , A . Anselmo & P . O . Gonçalves 276 ( BHCB); Monte Azul, Parque Estadual Caminho das Gerais, 14°55’44’’S, 43°02’53’’W, 13 June 2009, (fl.), P . L Viana et al 4263 ( BHCH). Retiro, 22 km da cidade, na estrada para Mato Verde , 15°’18’’ S , 42°45’32’’W, 1000 m, 17 March 1994, (fl.), V . C . Souza et al 5551 ( ESA); São Gonçalo do Abaeté , Rodovia BR-365, km 315, 16 July 1998, G . Hatschbach , M . Hatschbach & E . Barbosa 67943 ( MBM) . PIAUÍ: Santa Filomena, 25 July 1983, Fernandes , A . s.n. ( EAC). Tocantins: Novo Jardim, estrada para Placas, cerca de 2 km da divisa com a Bahia ( Rodovia TO-280), 11°49’17’’S, 46°21’44’’W, 20 July 2000, (fl.), V . C . Souza , J . P . Souza & J . O . Romão 24237 ( UEC) .

Distribution and ecology: — Chamaecrista orbiculata is endemic to Brazil and registered for the states of Bahia, Goiás, Mato Grosso, Mato Grosso do Sul, Minas Gerais, Piauí and Tocantins and the Federal District (Fig. 27C). It grows in cerrados densos, cerrados ralos or cerrados rupestres, campos limpos and campos sujos (Figs. 1B–G), in plane areas, hillsides or hill tops, on clayey, sandy-stony soils or sandstone outcrops or limestone, between altitudes of 700 and 1300 meters.

Flowering and fruiting: —Species collected with flowers and fruits from March to July.

Etymology: —The specific epithet “ orbiculata ” refers to the large and orbicular leaflets of the species.

Conservation status: —Due to its wide distribution, to form large populations (more than 80 mature individuals) and to have an Occurrence Extension Area of 598,430 km 2, Ch. orbiculata is being classified as Least Concern (LC), regarding its conservation.

Typification: —When Bentham described Cassia orbiculata in 1840 based on the “Claussen s.n.” he did not indicate its origin. Irwin & Barneby (1978) recognized for Cassia orbiculata four varieties ( Ch. orbiculata var. orbiculata , Ch. orbiculata var. cercidifolia , Ch. orbiculata var. ustulata , Ch. orbiculata var. tricothyrsus ) differentiated by the arrangement of the petals, an influence of the inflorescence, size of the sepals and petals, venation and thickened aspect of the margin of the leaflets, and presence of trichomes on them. In this same work, Irwin & Barneby (1978) reported that the collection used by Bentham (1840) in the original description of Ch. orbiculata , was actually “Claussen 167”, and indicated four other probable isotypes collected by “Claussen 849”. in the city of Curvelo, Minas Gerais, belonging to the herbariums C, GH, NY, P and S. Analyzing these collections, we realized that they were collected in different periods, places and by different collectors, and, therefore, one could not be admitted as a duplicate. On the other, neither consequently as isotypes or holotypes and vice versa, nor to be recognized as syntypes having seen only the “P. Claussen s.n.” collection (= P. Claussen 167) have been mentioned in the protologue of the species. Although Irwin & Barneby (1978) indicated the collection P. Claussen 167 deposited in the herbarium of K (K000555584) as a holotype of the species, it should not be considered as a holotype, since duplicates of this same collection exist in the herbariums G and F., we present the correct typification of the species, which starts to have as lectotype the collection P. Claussen 167 deposited in the herbarium of K under the Barcode K000555584 (Fig. 24), which in turn is reliable the original description of the species. We emphasize that the collection deposited in the herbarium K was chosen as a lectotype also because Bentham is a botanist whose majority of his collections exist in this herbarium.

Morphological relationships and characterization: —Species recognized by the arboreal habit, or sometimes shrubby with a conspicuously fissured bark and tortuous stem, cinereous as an adult, leaves with 2–4 pairs of leaflets with a horny and thickened margin, axis of inflorescences compacted with buds vines and very viscous or glabrous fruits and large flowers (2.7–6.6 cm long). It is morphologically related to Ch. celiae and Ch. cercidifolia due to their arborescent habit, stems and branches with conspicuously longitudinally cracked bark, orbicular or suborbicular follicles and viscous panicles. However, the characters listed in the table 1, in association, are certainly used to differentiate the species under discussion. Additionally, Ch. orbiculata is distributed in the Midwest (Federal District, Goiás, Mato Grosso and Mato Grosso do Sul), Northeast (Bahia and Piauí), North (Tocantins) and Southeast (Minas Gerais), while Ch. celiae and Ch. cercidifolia are endemic to Minas Gerais, but not sympatric to Ch. orbiculata .