Chamaecrista sparsifolia A. O. Souza & M. J. Silva, 2015

Souza, Alessandro Oliveira De & Silva, Marcos José Da, 2015, What’s new in Chamaecrista (Fabaceae, Caesalpinioideae) from the Brazilian Cerrado?, Phytotaxa 213 (3), pp. 253-262 : 254-261

publication ID	https://doi.org/ 10.11646/phytotaxa.213.3.5
persistent identifier	https://treatment.plazi.org/id/03C587DF-C719-FFF8-C780-E188FA6E268B
treatment provided by	Felipe
scientific name	Chamaecrista sparsifolia A. O. Souza & M. J. Silva
status	sp. nov.

Treatment

Chamaecrista sparsifolia A. O. Souza & M. J. Silva View in CoL , sp. nov. ( Figures 1 View FIGURE 1 and 2 View FIGURE 2 )

Diagnosis: ___ Shrubs 1.5–2.5 m tall, erect, slender, leaves sparsely distributed along the stem, panicles 24–45 cm long, with secondary axes preceded by small leaves, which assume the functions of the bracts, buds 8–15 mm long, sepals green to yellowish, densely setulose-viscous and puberulent externally, and pedicels 2–4 cm long.

Type: ___ BRAZIL. Goiás: Alto Paraíso de Goiás, Chapada dos Veadeiros, GO-239, entre Colinas do Sul e a Vila São Jorge , em encosta de morro, 14º11 ’ 58.1 ’’ S, 47º51 ’ 12.7 ’’ W, 954 m elev., 21 May 2014 (fl., fr.), A. O. Souza et al. 1050 (holotype: UFG!; isotype: UB!) GoogleMaps .

Shrubs 1.5–2.5 m tall, erect, slender, sparsely branched. Branches 30–80 cm long, cylindrical, robust, shortly setulose-viscous, and puberulent, including the pulvine, petiole, and rachis. Stipules 2.5–6(–9) mm long, linear, pubescent externally, persistent. Leaves 10–30 cm long, alternate spiral, conspicuously sparse and regularly distributed along the branches, plagiotropic, extrafloral nectary absent; pulvinus 2–4 × 2–4 mm, lightly dilated, poorly differentiated from the petiole, striated; petiole (1.5–)1.8–3.5(–4) cm; rachis 7.5–25(–28) cm long, cylindrical, sulcated above, green-yellowish; interfoliolar segments 3–7 mm long; pulvinule 1–1.5 mm long, lightly dilated, rugose; leaflets (11–)16– 35 pairs, with uniform size or slightly decreasing from the base to the tip of the rachis, the first pairs not reflexed or amplexicaul, surface slightly differentiated dorsiventrally; blades of the leaflets 0.8–2.6(–3) × 0.7–1.8(–2.2) cm, elliptic, broadly elliptic to suborbicular, apex obtuse or emarginate, with or without mucron, glabrous, divaricate, chartaceous, olivaceous-green, margin entire, plane, not ciliate, or very rarely puberulent, or setulose-viscous near inflorescence; venation brochidodromous, secondary veins 5–7 pairs, impressed and inconspicuous on the adaxial surface, and slightly prominent on the abaxial surface, tertiary veins immersed and inconspicuous on both surfaces. Panicles 24–45 cm long, including peduncle, terminal and axillary, emerging from the foliage, continuous with the branches; secondary axes with 10–30 flowers, regularly distributed at least on the superior third, robust, congested, with small leaves assuming the function of bracts, primary and secondary axes of the panicles setulose-viscous and puberulent, including pedicel and external surface of bracts and bracteoles. Bracts 2–3 × 0.5 mm, lanceolate, persistent. Bracteoles 1–1.5 × 0.5 mm, lanceolate, opposite or alternate, distributed from the middle third to the apex of the pedicel, persistent. Buds 0.8–1.2(–1.5) × 0.5–0.8 cm, widely elliptic, apex obtuse. Flowers 3–6.5 × 1.5–4 cm; pedicel 2–4 cm long, cylindric, robust; sepals 1.2–1.5 × 0.5–0.7 cm, elliptic, apex obtuse, membranaceous, densely setulose-viscous and puberulent externally, green-yellowish; petals 1.5–2.2 × 0.8–2.2 cm, obovate to widely obovate, inner petals asymmetric, falcate, coiled in the androecium, light yellow; stamens 10, 6–7 mm long, anthers mucronulate; ovary 5–6 × 1.3–1.5 mm, oblongoid, setulose and puberulent, styles 1–1.3 cm long, glabrous. Legume (4–)4.5–6.5 × 0.7–1(–1.2) cm, oblong, shortly setulose-viscous and puberulent, margin thickened, brown, valves charthaceous. Seeds 6–7 × 4.5–5 mm, orbicular, ocher to light brown, smooth, glossy.

Distribution and ecology: —Species probably endemic to the Chapada dos Veadeiros. Collections were performed in the municipality of Alto Paraíso de Goiás, near Vila São Jorge and along the dirt road toward the lodging of the Chapada dos Veadeiros National Park, and in the municipality of Colinas do Sul. Chamaecrista sparsifolia inhabits Cerrado ralo, scrub lands, hill slopes, and disturbed areas such as road edges, on clay-sandy and gravelly soils, between 950 and 1000 m elev.

Phenology: —Flowers and fruits of this species are found from April to October, but more often in June, while mature fruits can be found from October to January.

Etimology: —The specific epithet “ sparsifolia ” was chosen in reference to the new species have leaves notably spaced along the stem.

Conservation status: —The new species is herein considered rare because it is represented in herbaria collections by at most four specimens and also because in the field we found only three populations, with less than 20 individuals each. Furthermore, taking into consideration that the species occupies ca. 50 km 2, including the road side and a protected area (Chapada dos Veadeiros National Park), and that the surrounding area is subject to urban expansion, deforestation, and tourism, we also suggest to consider it a Critically Endangered (CR) B1; B2 ab (iii, iv) species according to IUCN (2014).

Additional specimens examined (paratypes): — BRAZIL. Goiás: Alto Paraíso de Goiás, Chapada dos Veadeiros, Parque Nacional da Chapada dos Veadeiros, entre a Vila São Jorge e o rio Preto , 19 October 1990 (fl.), G. M. Hatschbach & J. M. Silva 54778 (NY) ; ibd., em campo sujo úmido, 21 October 2011, (fr.), M. J. Silva et al. 3815 ( UFG) ; ibd., campo de Vellozia , no lado esquerdo da entrada para o alojamento dos brigadistas, 20 January 2012 (fr.), M. M. Dantas 75 ( UFG) ; ibd., próximo da cancela de acesso ao alojamento dos brigadistas do Parque Nacional da Chapada dos Veadeiros , em campo sujo, 19 April 2012 (fl.), M. M. Dantas & M. J. Silva 233 ( UFG), 235 ( UFG) ; ibd., 26 May 2012, (sterile) M. M. Dantas & M. J. Silva 329 ( UFG), 330 ( UFG), 331 ( UFG) ; Parque Nacional da Chapada dos Veadeiros , primeiro morro antes do cânion 1, encosta de morro, 29 September 2012 (fr.), M. J. Silva et al. 4435 ( UFG) ; Chapada dos Veadeiros, GO-239, entre Colinas do Sul e a Vila São Jorge , em encosta de morro, 14º11 ’ 58.1 ’’ S, 47º51 ’ 12.7 ’’ W, 954 m elev, 21 May 2014 (fl., fr.), M. J. Silva et al. 5985 ( UFG), 5986 ( UFG), 5987 ( UFG) GoogleMaps ; ibd., 21 May 2014 (fl., fr.), A. O. Souza 1045 ( UFG), 1046 ( UFG), 1047 ( UFG), 1048 ( UFG), 1049 ( UFG) ; ibd., aproximadamente 2 km da entrada de acesso aos alojamentos do Parque Nacional da Chapada dos Veadeiros, em direção à Vila São Jorge , 6 September 2014 (fr.), A. O. Souza et al. 1316 ( UFG), 1317 ( UFG) .

Taxonomic comments: — Chamaecrista sparsifolia must be included in Chamaecrista section Absus subsection Absus series Rigidulae because it is setulose-vicous at least in the inflorescence, absence of extrafloral nectary, spiral alternate leaves, leaflets divaricate with impressed and inconspicuous veins, and panicled inflorescence.

Chamaecrista sparsifolia has just a few collections and is represented in herbarium collections by at most four specimens, usually indeterminate or identified as C. nummulariifolia (Benth.) H.S. Irwin & Barneby. However , it can be clearly distinguished from C. nummulariifolia by having shrubby habit, with plants greater than 1.5 m tall, leaves with (11–)16–35 pairs of leaflets, with petiole greater than 1.5 cm long (vs. subshrubby habit, with plants up to 1 m tall, leaves with 6–11 pairs of leaflets, sessile or with petiole up to 0.8 cm long in C. nummulariiafolia ).

Regarding the other species of Chamaecrista ser. Rigidulae , C. sparsifolia shares leaves with more than 16 pairs of leaflets with C. azulana , C. filicifolia , C. dawsonii , and C. gymnothyrsa . But the two first ones are subshrubs, have sessile or subsessile leaves with the first pair of leaflets amplexicaul, and leaflets with trichomes on both surfaces, characters that do not occur in C. sparsifolia . The new species is morphologically more similar to C. dawsonii and C. gymnothyrsa , especially the latter, since they share leaflets broadly elliptic, orbicular or suborbicular, more than 1 cm long, and inflorescences larger than 24 cm long. The characteristics listed in Table 1 are helpful to distinguish C. gymnothyrsa from C. sparsifolia . Although both C. sparsifolia and C. gymnothyrsa are endemic to the Chapada dos Veadeiros, they are not sympatric, because the former is found in the municipalities of Alto Paraíso de Goiás and Colinas do Sul, while the latter is found only in the municipalities of Cavalcante ( Figure 5B View FIGURE 5 ).

Chamaecrista obolaria (H.S. Irwin & Barneby) A.O. Souza & M.J. Silva , stat. nov. Chamaecrista chaetostegia var. obolaria (H.S. Irwin & Barneby) H.S. Irwin & Barneby, Mem. View in CoL New York Bot. Gard. 35: 654. 1982. Basionym: Cassia chaetostegia var. obolaria H.S. Irwin & Barneby, Mem. View in CoL New York Bot. Gard. 30: 139. 1978. ( Figures 3 View FIGURE 3 and 4 View FIGURE 4 ).

Type: — BRAZIL. Goiás: Chapada dos Veadeiros, in cerrado rocky hillside, with crystalline outcrops, 13 March 1969, (fl.), ca. 35 km north of Alto Paraíso de Goiás (= Veadeiros), H.S. Irwin et al. 24275 (holotype: UB!, isotypes: C!, F!, GH!, K!, LE, NY!, RB!, S, UC, US).

Shrubs 1.5–2.3 m tall, erect, slender. Stems usually monopodial or more rarely with short lateral branches (5.5–14.5 cm long), near apex, densely leafy, cylindrical to angulose, puberulent or setulose-viscous, including petiole and rachis. Stipules 6–12 mm long, linear, puberulent, persistent. Leaves 5.5–12 cm long, regularly distributed and very densified along the stems, sessile or subsessile; pulvinus 2–3 mm long, lightly dilated, similar to petiole, puberulent, striated; petiole 0–4 mm long; rachis 5–11.5 cm long, cylindrical, sulcated above; interfoliolar segments 4–7 mm long; pulvinule 0.3–0.5 mm long, smooth; leaflets 11–18 pairs, 1.1–2.2(–2.5) × 0.8–2.2(–2.5) cm, with uniform size along the rachis, the first and sometimes the second pairs reflexed and amplexicaul, widely orbicular or suborbicular, apex emarginate, rounded or obtuse, glabrous, divaricate, chartaceous, green-olivaceous to green opaque, margin entire, plane, glabrous to ciliate near inflorescence; venation brochidodromous, secondary veins 6–9 pairs, conspicuous, slightly prominent on both surfaces, tertiary veins intrinsically cross-linked, conspicuous, slightly prominent on abaxial surface. Panicles 4–9.5 cm long, terminal or sometimes axillary, emerging from the foliage, continuous with the branches, secondary axes with 5–15 flowers, congested, puberulent or setulose-viscous, including pedicel and external surface of bracts and bracteoles. Bracts 4–7 × 1 mm, lanceolate. Bracteoles 2–2.5 × 1 mm, lanceolate, opposite or alternate, distributed from the middle third to the apex of the pedicel. Buds 7–10 × 4–8 mm, ovate to elliptic, apex acute or apiculate. Flowers 2.4–3.7 × 1.2–2 cm; pedicel 1.2–2.2 cm long, cylindric, thin; sepals 10–15 × 4.5–5 mm, oblong-elliptic, apex acute, membranaceous, glabrous to puberulent, green-yellowish externally; petals 1–2 × 1–1.5 cm, obovate to widely obovate, inner petals asymmetric, falcate, coiled in the androecium, light yellow; stamens 5–6.5 mm long, anthers mucronulate; ovary 3–4 × 1–1.5 mm, oblongoid, densely villous, long setose, yellowish; styles 6–7.5 mm long, pubescent. Pods 3–4.5 × 0.6–1 cm, oblong, puberulent, setose-viscous, with spiny aspect, margin thickened, brown, valves chartaceous. Seeds 5–6 × 3–4 mm, romboid to oblong, dark-brown, smooth, glossy.

Additional specimens examined: — BRAZIL. Goiás: Cavalcante, Reserva Particular do Patrimônio Natural (RPPN) Varanda da Serra , 13º49 ’ 22,9 ’’ S, 47º27 ’ 28,8 ’’ W, 750 m elev., 20 May 2004 (fl), M. L. Fonseca et al. 5359 ( IBGE) GoogleMaps ; ibd., estrada na saída de Cavalcante em direção ao povoado Kalunga , 7 February 2013 (fl), A. O. Souza et al. 146 ( UFG), 152 ( UFG), 154 ( UFG) ; ibd., estrada de Cavalcante para Colinas do Sul, a aproximadamente 3 km do Sítio Gaivota e cerca de 9 km de Cavalcante, 29 January 2014 (fl), A. O. Souza et al. 864 ( UFG), 865 ( UFG). Teresina de Goiás, Chapada dos Veadeiros, 5 km antes da cidade, 25 May 2014 (sterile), M. J. Silva et al. 5889 ( UFG) ; ibd., 21 km de Cavalcante em direção ao Vão do Moleque, 500 m após a entrada para o povoado Kalunga , lado esquerdo da estrada, cerrado rupestre de encosta, 25 July 2014 (fr), M. J. Silva & R. C. Sodré 6047 ( UFG), 6048 ( UFG), 6049 ( UFG) ; ibd., primeira entrada à direita antes de chegar a Cavalcante , morro à esquerda da estrada de terra, 26 July 2014 (fr), M. J. Silva & R. C. Sodré 6122 ( UFG) .

Taxonomic Comments: —Irwin & Barneby (1978) recognized two varieties of Cassia chaetostegia Irwin & Barneby : C. chaetostegia var. chaetostegia and C. chaetostegia var. obolaria Irwin & Barneby. The first one was described based on collections H. S Irwin et al. 9554 and H. S. Irwin et al. 1154, from Chapada da Contagem, in the municipality of Brasília, while the second one was described based only on collection H. S Irwin et al. 24275, from Chapada dos Veadeiros, between the municipality of Alto Paraíso de Goiás and Cavalcante. According to Irwin & Barneby (1978), both varieties shared the shrubby habit, ranging from 1.5 to 2 m tall, sessile leaves regularly distributed along the stem, stipules more than 0.5 mm long, and flowers up to 9 cm long. However, these taxa could be differentiated by the presence and type of trichomes on the leaflets, branches, and fruits, the aspect of tertiary veins, and the distribution of trichomes on the leaflets. Irwin & Barneby (1982) proposed the transference of Cassia chaetostegia to the genus Chamaecrista and the new combination C. chaestostegia var. obolaria (H.S. Irwin & Barneby) H.S. Irwin & Barneby.

Based on the analysis of a larger number of collections (25), the disjunct distribution of the infraspecific taxa of C. chaetostegia , its environmental preferences, and also the differences related to leaflets (size, shape, and trichome type), inflorescences (number of flowers), flowers (trichomes, type of sepals, and ovary), and fruits (size and trichome type), we decided to raise C. chaetostegia var. obolaria to species level and designate it as Chamaecrista obolaria .

We would also like to point out that the category variety was mistakenly applied to C. chaetostegia by Irwin & Barneby (1982), given that in taxonomy this category corresponds to sympatric taxa with morphological variations which are not significant enough to be recognized as distinct species (Clausen 1941, McDade 1995). This does not occur with the taxa of C. chaetostegia , because they present both disjunct distribution and more morphological differences from each other than from other taxa of the genus.

In C. obolaria the leaflets are 1.1–2.2(–2.5) × 0.8–2.2(–2.5) cm, wide orbicular or suborbicular, emarginate or rounded at the apex, glabrous on both surfaces, with intrinsically cross-linked tertiary veins; the panicles have 5–15 flowers; the sepals are glabrous to puberulent; the ovary is densely villous and long setose, yellowish; and the fruits are 3–4.5 cm long, setose-viscous and puberulent with spinescent aspect. In C. chaetostegia the leaflets are 0.7–1.2 × 0.5–1 cm, oval to oblong-elliptic, with apex obtuse and apiculate, pubescent on both surfaces, with single tertiary veins; the panicles possess 15–24 flowers; the sepals are setulose-viscous and puberulent; the ovary is shortly setulose-viscous and puberulent; and the pods are 2–2.8 cm long, with the surface similar to that of the ovary.

On the one hand, C. obolaria seems to be endemic to the Chapada dos Veadeiros, where it was collected in the municipalities of Cavalcante and Teresina de Goiás. It grows in Cerrado sensu stricto, in open environments, on clayey soils, rocky hillsides, and rocky outcrops, between 750–1000 m elev. While, C. chaestostegia is known only in the Chapada da Contagem, in the Federal District, where it grows on steep hillsides and margins of gallery forests ( Figure 5A View FIGURE 5 ). Chamaecrista obolaria has flowers from January to May and fruits from May to July.

Conservation Status: — Chamaecrista obolaria can be considered a rare species, because it is represented by few collections (up to 5) in herbaria and forms populations with few individuals (up to 10). It grows in an area less than 10 km 2, in a habitat subject to human disturbance due to tourism, accidental fires, and slash and burn to clear the area for cattle pasture or food crops. Therefore we propose to consider it an endangered species according to IUCN (2014).