Chamaecrista frondosa M.J. Silva & A.O. Souza, 2014

Silva, Marcos José Da & Souza, Alessandro Oliveira De, 2014, A new species of the genus Chamaecrista (Leguminosae, Caesalpinioideae) from Chapada dos Veadeiros, Goiás, Brazil, Phytotaxa 174 (3), pp. 181-186 : 182-184

Chamaecrista frondosa M.J. Silva & A.O. Souza , sp. nov. ( Figure 1 )

Species similar to C. psoraleopsis in its general leaflet shape, but differs from it due to stem densely ramified, virgate and cespitose with more than 10 branches from the base, a globose canopy, leaflets pubescent to setulose, including margin, and pulvinule 0.8–1.2 mm.

Type: — BRAZIL. Goiás: Município de Alto Paraíso de Goiás. Parque Nacional da Chapada dos Veadeiros, 1,5 km a partir da Torre na margem da trilha que leva à Cachoeira das Sete Quedas, 14º06’33,4”S, 47º44’55,2”W, 1057 m, 2 August 2013, (fl, fr), M . J . Silva et al. 5195 (holotype: UFG!; isotype: UB!, CEN!) .

Subshrub 0.3–1 m high, cespitose, erect, perennial, densely ramified, with globose canopy.Adult branches cylindrical to angulate, sparsely puberulent to glabrescent and grayish brown; young branches setose-glandular and viscous, together with petiole, foliar rachis, inflorescence, pedicel, external surface of the stipules, and sepals. Stipules 1–2.5 × 0.1–0.2 mm, linear to subulate, persistent. Leaves 2–6 cm long, alternate or spiral; extrafloral nectary absent; petiole 9–16 mm long, cylindrical, without wings; rachis 1.5–4.3 cm long; interfoliolar segments 5–11 mm long; leaflets 3–5(6) pairs, blade 7–23 × 1.5–4 mm, lanceolate to oblanceolate or oblong, resin-dotted, apex acute and mucronulate, base oblique, margin plane, villosulous-ciliate and setulose, carthaceous, olivaceous-green to grayish when adult, surface slightly differentiated dorsiventrally, upper and lower surface pubescent and setulose, mainly on midrib of the lower surface; venation brochidodromous, veins impressed on upper surface, midrib slightly prominent on lower surface. Raceme 2.5–5 cm long, terminal and axillary, prefloration subcorymbose with 4–8 flowers. Bracts 2.5–5 × 0.5 mm long, linearlanceolate, setose-villosulous externally, persistent. Buds 5–10 × 3–7 mm, ovate to oval-elliptic, acuminate at apex. Flowers 2–3.5 cm long, pedicel 1.3–2.5 cm long; bracteoles 2–3.5 × 0.1–0.15 mm, linear, setose-villosulous externally, persistent; sepals 8–12 × 2.5–5 mm, elliptic or oval-elliptic, conspicuously acuminate at apex, concave, yellowish with a central purplish band; petals 10–15 × 7–11 mm, light yellow, oblong-obovate to obovate, inner petals asymmetricfalcate, coiled in androecium; fertile stamens 10, 3– 5 mm long, anthers 2.7–4 mm long, oblongoid, pubescent on lateral sutures; ovary 2–3 × 0.7–1.8 mm, oblongoid, densely glandular, setose, sessile, styles 4–6 mm long, glabrous. Pod 16–25 × 4–6 mm, oblong, setulose and shortly tomentose, brown to reddish when mature and green-vinaceous when young, valves chartaceous. Seeds 3–4 × 1.5–2.5 mm, obovate, smooth, blackened, and glossy.

Additional specimens examined (paratypes): — BRAZIL. Goiás: Alto Paraíso de Goiás, Parque Nacional da Chapada dos Veadeiros, imediações do rio Preto , cerca de 300 m acima do Cânion 2, 14º9.3’5” S, 47º48.6’42” W , 1005 m, 29 September 2012 (fl, fr), M . J . Silva et al. 4438 ( UFG), 4439 ( UFG); 27 October 2012 (fl, fr), M . M . Dantas, M . J . Silva & R . C . Sodré 388 ( UFG), 390 ( UFG), 391 ( UFG); ibd., 800 m acima do Cânion 2, margeando o rio Preto , 14º08’30.6”S 47º47’56.9”W, 1044 m, 27 October 2012 (fl, fr), M . J . Silva et al. 4511 ( UFG), 4512 ( UFG), 4513 ( UFG), 4514 ( UFG); Aproximadamente 3 km a partir do rio Preto , 14º07’47.3”S 47º45’57.4”W, 1118, 21 June 2013 (fl, fr), A . O . Souza et al. 435 ( UFG), 436 ( UFG), 437 ( UFG), 438 ( UFG), 439 ( UFG), 442 ( UFG), 443 ( UFG); 2,7 km a nordeste da casa dos pesquisadores, 14º07’40.8”S 47º46’07.7”W, 1138 m, 21 June 2013 (fl, fr), M . J . Silva et al. 4090 ( UFG), 4091 ( UFG), 4092 ( UFG), 4093 ( UFG), 4094 ( UFG), 4095 ( UFG), 4096 ( UFG); 1,5 km a partir da torre na margem da trilha que leva à Cachoeira das Sete Quedas, 14º06’33.4”S 47º44’55.2”W, 1057 m, 02 August 2013, (fl, fr), M . J . Silva et al. 5196 ( UFG), ibd., 2,85 km a partir da torre que leva à Cachoeira das Sete Quedas, 14º06’8.3”S 47º44’57.2”W, 1103 m, 02 August 2013 (fl), M . J . Silva et al. 5203 ( UFG). Cavalcante, 900 m a partir do rio Preto , após a Cachoeira das Sete Quedas, 14º05’37.1”S 47º44’56.9”W, 1065 m, 02 August 2013, (fl), M . J . Silva et al. 5213 ( UFG); 1 km a partir do rio Preto , após a Cachoeira das Sete Quedas, 14º05’40.9”S 47º45’5.8”W, 1062 m, 02 August 2013, (fl), M . J . Silva et al. 5227 ( UFG) .

Distribution and ecology: — Chamaecrista frondosa appears to be endemic to the Chapada dos Veadeiros, in the northern part of the state of Goiás, Brazil, where it grows forming dense populations ( Figure 2 ) between 1005 and 1138 m elev. in rocky outcrops in the Cerrado sensu stricto and rocky fields on sandy-clayey soils. Chapada dos Veadeiros, a region where different types of vegetation grow (e.g. grassland, rocky fields, Cerrado rupestre, Cerrado sensu stricto, veredas, clear grassland, scrubland, gallery forest, mesophytic deciduous forest, and semi-deciduous forest), exhibits high floristic diversity and several endemic species, including Chamaecrista ( Irwin & Barneby 1982) .

IUCN Red List Category: — Chamaecrista frondosa , known to grow only in the Chapada dos Veadeiros region, is undoubtedly rare, despite being locally abundant, and therefore is herein provisionally considered Critically Endangered under criterion CRb1, according to the IUCN red list criteria ( IUCN 2010). However, botanical knowledge of the legume flora of the Chapada dos Veadeiros is incomplete, and more field surveys are needed to establish how widely distributed this species is.

Phenology: — Chamaecrista frondosa has been collected with flowers and fruits from June to October. Flowering is more pronounced in July and fruiting is more abundant in October.

Etymology: —The specific epithet alludes to the subshrubby and canopy habit performed by stem cespitose densely ramified and leafy.

Relationships and Systematic Position: — Chamaecrista sect. Absus ser. Microphyllae has 18 species distributed in the Brazilian Central Plateau, especially in montane areas of the Distrito Federal and the state of Goiás, the first state in number, represented by 14 species ( Irwin & Barneby 1982). This series includes shrubs and subshrubs usually with 8–40 pairs of leaflets upward in the rachis and partly facing each other, with small and little differentiated dorsiventrally blade, as well as young branches and inflorescences with glandular trichomes and petioles without extrafloral nectaries ( Irwin & Barneby 1982). Since these characters also occur in Chamaecrista frondosa , it is here suggested the inclusion of the species in this series, although it would be the only species of the series presenting leaves with few pairs of leaflets.

Among the species of Chamaecrista sect. Absus ser. Microphyllae , Chamaecrista frondosa is more morphologically similar to C. psoraleopsis Irwin & Barneby (1982: 653) , because both share subshrubby habit, stipules diminute (up to 4 mm long), leaflets lanceolate to oblanceolate, resin-dotted and smaller than 2.5 cm long, and inflorescence congestous with 3–5 flowers. However, C. frondosa has stems densely branched, forming a canopy due to its dense foliage, leaflets with upper and lower surface pubescent and setulose, with margin villosulous-ciliate and setulose, trichomes with dilated basin and pulvinule conspicuously differentiated (0.8–1.2 mm), while C. psoraleopsis is not branched or sparsely branched, decumbent or suberect, but without canopy, has leaflets with both surfaces glabrous, conspicuously resin-dotted, with margin microscopically ciliated, and pulvinule absent or up to 0.4 mm long.

Additionally, in Chamaecrista psoraleopsis the leaves are distributed regularly and sparsely along the stem, with rachis and petiole not sulcate, and it usually has 7–16 pairs of leaflets in adult leaves. In contrast, in C. frondosa the leaves are grouped in the apex of the multiple branches, rachis and petiole are conspicuously sulcate, and the adult plant has 3–5 pair of leaflets.Although both species are from Chapada dos Veadeiros region, C. psoraleopsis occurs in Cerrado sensu stricto and grows on rocky ridges and grasslands on hillsides, while C. frondosa grows in rocky outcrops in Cerrado sensu stricto and in rocky fields on sandy-clay soils. The following key helps identify the species of Chamaecrista ser. Microphyllae occurring in the Chapada dos Veadeiros region.

Figures

FIGURE 1. Chamaecrista frondosa. A. Habit. B. Stipule. C. Leaf. D. Leaflet. E. Leaflet, showing glands and villosulous trichomes on lower surface. F. Detail of inflorescence, showing prefloration subcorymbose. G. Sepals. H. Petals. I. Androecium. J. Stamen. K. Gynoecium. L. Fruit. M. Seed, side view. From M. J. Silva, R. C. Sodré, F. K. L. Silva, A. O. Souza & L. L. C. Antunes 5195 (UFG). Illustrated by Cristiano Gualberto.

FIGURE 2. Chamaecrista frondosa. A. habitat. B. Plant height. C. Habit (observe the globose canopy). D. Inflorescence (observe the vinaceous buds and yellowish trichomes). E. Flowers. F. Detail of the fruiting branch. Photos taken by Marcos José da Silva.