Chamaecrista deltoidea Hervencio & L.P.Queiroz

Paula Hervencio, & Luciano P. de Queiroz. (2004). A New Species of Chamaecrista sect. Absus (Leguminosae-Caesalpinioideae) from Minas Gerais, Brazil. Kew Bulletin, 59(1), 149-151. doi:10.2307/4111091

Type

Brazil, Minas Gerais, R. Simdo-Bianchini & S. Bianchini CFSC 12770 (holotypus: SPF; isotypus: HUEFS).

Morphology General Habit

Shrub with few branches, height not known; indumentum of simple, unbranched, erect trichomes interspersed with dark glandular hairs on the main stem, branches, peduncles, pedicels, and outer surface of the sepals

Morphology Leaves Stipules

Stipules triangular, soon deciduous, 0.5 - 1.5 x 0.3 - 0.4 mm

Morphology Leaves

Leaves scattered, not imbricate, sessile, ascending, 2-foliolate; leaf axis absent, but a stout, setiform, terminal appendage present, c. 1.2 mm long; leaflets chartaceous, 42 - 55 x 32 - 50 mm, deltoid, apex obtuse, shortly mucronate from the excurrent midrib, mucro 0.4 - 0.7 x 0.3 - 0.5 mm, base cordate, adaxial surface pubescent, with simple unbranched trichomes, abaxial surface with glandular hairs scattered over the midrib, main venation pattern pinnate, secondary veins inconspicuous, brochidodromous, tertiary veins fine, inconspicuous, reticulate

Morphology Reproductive morphology Inflorescences

Inflorescence a lax corymbose raceme, terminal or axillary, 4 - 5-flowered; peduncle 0.7 - 1.1 cm long; rachis 4 - 5.5 cm long; pedicels 3.5 - 3.7 cm long; bracts triangular, persistent 1.5 - 2 x 0.4 - 0.5 mm; bracteoles triangular, persistent 1.7 - 1.9 x 0.5 - 0.9 mm

Morphology Reproductive morphology Flowers

Floral bud ovoid, acute; flower c. 26 mm diam.; sepals elliptic, acute, 1.7 - 2.2 x 0.6 - 0.8 cm; lateral petals 4, obovate, 1.9 - 2 x 1.5 - 2 cm, claw absent, internal standard petal asymmetric, obovate, c. 2.2 x 1.2 cm, partially enclosing the androecium; stamens subisomorphic, anthers 4 - 5.8 mm long, glabrous except for the lateral suture villosulous, filament 1.3 - 2.5 mm long

Morphology Reproductive morphology Flowers Gynoecium Ovary

Ovary sericeous, the silky hair interspersed with dark glandular hairs, c. 8-ovulate, style 1.1 - 1.6 cm long, curved at the apex, glabrous

Morphology Reproductive morphology Fruits

Pod oblong-linear, c. 4.2 cm long, c. 1 cm wide; valves leathery, pubescent, with simple eglandular hairs interspersed with dark glandular hairs.

Distribution

Brazil, Minas Gerais

Phenology

Chamaecrista deltoidea was collected in June, with flowers and fruits

Ecology

On rock outcrops near gallery forest along the Córrego Lajeado.

Note

This new species is at once distinguished from the other species in Chamaecrista sect. Absus by its sessile leaves and deltoid, broad leaflets. The leaflets are discolorous and chartaceous and the inflorescences are lax, corymbose racemes, with relatively large flowers. This species is included in subsection Absus due to the absence of extrafloral nectaries, the presence of glandular hairs, and the androecium of 10 stamens partially enclosed by the obovate falcate asymmetrical standard petal. It is probably related to series Unijugae (first described in Cassia by Irwin & Barneby 1977), that comprises only two species: Chamaecrista monticola (Benth.) H. S. Irwin & Barneby and Chamaecrista catapodia (H. S. Irwin & Barneby) H. S. Irwin & Barneby. The series is recognised by the presence of bifoliolate, sessile leaves that are subvertically imbricate along the main branch, leaflets widely ovate, concolorous, more or less cordate-amplexicaul at the base and on the proximal side and with acuminate floral buds. Chamaecrista deltoidea may be distinguished from these two species by its scattered leaves, not imbricate along the stem, larger leaflets (42 - 55 x 32 - 50 mm) and larger flowers (c. 26 mm diam.) in a lax inflorescence.

Conservation

Despite an intensive programme of floristic inventory carried out in the Serra do Cipó over the last 28 years, this new species has only been collected once, from a remote area known as Salitreiro. In spite of three subsequent visits to the area, all attempts to recollect the species have proved unsuccessful. Thus, although Ch. deltoidea occurs in a remote part of a protected area (The National Park of the Serra do Cipó), it could be considered a threatened species due its extreme rarity.