Rhynchosia mineira L.M.P.Bezerra & Fort.-Perez

de Paula Alves Bezerra, L.M., de Vargas, W. et al. (2019). Rhynchosia mineira (Leguminosae: Papilionoideae), a new and critically endangered species from Minas Gerais, Brazil. Kew Bulletin 74: 62. https://doi.org/10.1007/s12225-019-9852-z

Type

Brazil, Minas Gerais, Couto de Magalhães de Minas, BR-367 towards São Gonçalo do Rio Preto, 18°3'17.2"S, 43°26'00.2"W, alt. 995 m, 17 July 2017, (fl., fr.), T. C. Monteiro, A. P. Fortuna-Perez, W. Vargas, P. H. Murashima & K. R. Mendes 79 (holotype BOTU!; isotypes: K!, NY!).

Morphology General Habit

Prostrate subshrub

Morphology Stem

Stems few-branched, pubescent with yellow hairs, and non-glandular trichomes and punctiform glands

Morphology Leaves Stipules

Stipules persistent, free, ovate, apex acute, 5 – 10 × 3 – 4 mm, externally pubescent and with yellow punctiform glands

Morphology Leaves Stipel

Stipels absent

Morphology Leaves

Leaves trifoliolate, persistent; petioles 1.5 – 2.4 cm long

Morphology Leaves Leaflets

Leaflets discoloured, 2.6 – 3.8 × 1.5 – 3.1 cm, pubescent, with glands on the abaxial surface, rhomboid to ovate, apex cuneate, base rounded to truncate, margins entire

Morphology Reproductive morphology Inflorescences

Corymbiform inflorescences 1.7 – 2.5 cm long, not exceeding the length of the leaf, crowded, 7 – 11-flowered

Morphology Reproductive morphology Inflorescences Bracts

Bracts ovate, persistent, 3 – 7 mm long; pedicel 1 – 2 mm long

Morphology Reproductive morphology Flowers

Flowers 7 – 8 mm long, yellow; calyx 5-lobed, 9 – 10 mm long, pubescent and with yellow punctiform glands, lobes lanceolate, equal to, or exceeding corolla in length; standard 6 – 7 × 3 – 4 mm, obovate, apex rounded, externally glabrous, with punctiform glands, claw 1 – 1.5 mm long, auricle c. 0.5 mm long; wing petals 5 – 6.5 × 1 – 1.5 mm, obovate, claw c. 1.5 mm long, auricle c. 1 mm long; keel petals 6.5 – 7 × 2 – 2.5 mm, falcate, claw c. 2 mm long; stamens c. 7 mm long; ovary c. 2 mm long, hairy; style c. 4 mm long, stigma minute

Morphology Reproductive morphology Fruits

Fruit 1.5 – 2.1 × 0.5 – 0.6 cm, oblong to elliptical, flat-compressed, greenish, pubescent and with yellow punctiform glands; only immature seeds seen.

Note

Rhynchosia mineira resembles R. arenicola Hassl. as both possess a corymbiform inflorescence that does not exceed the length of the leaf, and calyx lobes that equal or exceed the length of the corolla. They are easily differentiated by their stipules, which are ovate, 5 – 10 mm long in R. mineira (vs lanceolate, c. 2 mm long in R. arenicola); the habit, which is prostrate in R. mineira (vs erect in R. arenicola); the densely pubescent stem (vs stem glabrescent in R. arenicola); and in the leaflets being ovate to rhomboid (vs elliptical in R. arenicola). In the state of Minas Gerais, besides R. mineira, there is just one species of Rhynchosia, R. claussenii Benth., in which the inflorescence does not exceed the length of the leaf. However, the two are easily differentiated by their habit, which is prostrate in R. mineira (vs erect in R. claussenii); by the calyx lobes, which are lanceolate in R. mineira (vs ovate in R. claussenii); and by the stems, which are abundantly hirsute in R. mineira (vs pubescent in R. claussenii). The species was named Rhynchosia mineira because it was collected in the state of Minas Gerais, which is one of the main centres of diversity of the Leguminosae family and of the genus Rhynchosia in Brazil.

Distribution

Rhynchosia mineira occurs in the municipality of Couto de Magalhães de Minas in Minas Gerais state, Brazil, and grows in “campo rupestre” (rocky fields) inside cerrado vegetation

Ecology

The species was collected alongside a road in the Espinhaço Range of Brazil, where it grows in “campo rupestre” (rocky fields) on sandy soil; it occurs together with grasses and other legume species, such as Poiretia elegans Cl.Müll. and Stylosanthes spp.

Conservation

In accordance with the IUCN red list criteria (IUCN Standards and Petitions Subcommittee 2017), we assess the conservation status as Critically Endangered (CR) based on criteria B2a and B2b (iii). Rhynchosia mineira occurs in only one known location, a degraded environment where there are agricultural crops and pasture.

Phenology

Collected in flower and fruit in July.