Rhynchosia franciscana L.P. Queiroz & D.B.O.S. Cardoso, Syst. Bot.

Bezerra, Luísa Maria De Paula Alves, Cândido, Elisa Silva, Vargas, Wanderleia De, Torke, Benjamin Marland, Lewis, Gwilym Peter & Perez, Ana Paula Fortuna, 2024, Taxonomic revision of Rhynchosia Lour. (Leguminosae, Papilionoideae, Phaseoleae) in South America, Phytotaxa 643 (1), pp. 1-67 : 31

11. Rhynchosia franciscana L.P. Queiroz & D.B.O.S. Cardoso, Syst. Bot. 43(4): 975. 2018. Type:— BRAZIL, Bahia, Mun. Casa Nova, Fazenda Santarém , 9°31’47” S, 41°21’34’’ W, October 2004 (fl./fr.), L. P. de Queiroz et al. 9639 (Holotype: HUEFS 89016 [digital image!]). Iconography: Systematic Botany, 43(4): 976. 2018.

Vine herbaceous or suffrutescent, twining, stems branching, villous, indumentum light yellow, with yellow vesicular glands, but lacking bulbous-based trichomes. Stipules caducous. Leaves trifoliolate; petiole 2–2.4 cm long; leaf rachis 0.6–0.8 cm long; stipels caducous; leaflets 3.8–4.3 x 2.8–3 cm, deltoid or ovate, surface not bullate, obtuse at apex and base, margin entire, tomentose, with yellow vesicular glands on both surfaces. Inflorescences axillary, racemose or paniculate, 15.5–19 cm long, many-flowered, exceeding the length of the subtending leaf; bracts caducous; pedicel 5–6 mm long. Flowers 35–39 mm long excluding the pedicel; calyx 15–17 mm long, pubescent, with yellow vesicular glands, but lacking bulbous-based trichomes, lobes lanceolate to triangular, not exceeding the corolla in length; standard petal 20–22 × 18–20 mm, elliptical, emarginate at apex, pilose, with yellow vesicular glands, but lacking bulbous-based trichomes, claw ca. 7 mm long, auricle ca. 2 mm long; wing petals 10–12 × 4–5 mm, oblong, claw ca. 5 mm long, auricle 2 mm long; keel petals 17–18 × 8–9 mm, falcate, claw ca. 7 mm long; stamens ca. 25 mm long; ovary ca. 6 mm long, pubescent, with yellow vesicular glands. Fruits ca. 5 × 1 cm, brownish, without constrictions between the seeds, oblanceolate, tomentose, with yellow vesicular glands, but lacking bulbous-based trichomes. Seeds ca. 6 × 5 mm, reniform, unicolored, brown.

Nomenclatural and taxonomic notes: —The species is easily distinguishable from other South American taxa by its relatively large, 35–39 mm long flowers.

Reproductive phenology: —Flowering in June and October; fruiting in June, September and October.

Distribution and habitat: — Rhynchosia franciscana is an endemic species from the sand dunes of the middle São Francisco River, within the Caatinga Seasonally Dry Woodlands, in the state of Bahia, Brazil, in the municipalities of Barra and Casa Nova ( Fig. 8 ; Queiroz & Cardoso 2018).

Conservation status: —Based on an EOO of 7,832 km 2 (GeoCAT, accessed in May 2022), R. franciscana is classified as VU B1a + B1b (i) following the IUCN red list criteria and subcriteria ( IUCN 2022). The application of the subcriteria is justified on the grounds that this species seems to be rare, since there are just a few known herbarium collections, and this Rhynchosia species has never been detected outside the dunes of the middle São Francisco River in the Brazilian state of Bahia ( Queiroz & Cardoso (2018).

Selected Specimens Examined:— BRAZIL. Bahia: Barra, dunas interiores da margem esquerda do médio rio São Francisco , June 200 (fl.), A. T. Rodarte 86 ( ALCB) ; Casa Nova , 10 km do asfalto da BR 235, direção pau a pique, 18 September 1989 (fr.), G Fotius 4251 ( ALCB, INPA) ; ibid., ca. 30 km de Remanso para Casa Nova , June 2001 (fr.), T. S. Nunes et al. 532 ( ALCB, CEPEC) .

Figures

FIGURE 8. Geographical distribution of Rhynchosia franciscana and R. lewisii, both species endemic to Bahia state, Brazil.