Rhynchosia naineckensis Fortunato, Darwiniana, 1982

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 : 49-50

21. Rhynchosia naineckensis Fortunato, Darwiniana 24: 497–498. 1982. Type:— ARGENTINA, Formosa: Dep. Pilcomayo, Laguna Naineck , ruta 86, km 1334 ½, August 1981 (fr.), R. Fortunato et al. 57 (Holotype: BAB 00000498 [digital image!]; isotype: SI 002522 [digital image!]). Iconography: Rodriguésia 70: 13. 2019

Vine suffrutescent, twining, stems branched, pilose, indumentum white to light yellow, with yellow vesicular glands, but lacking bulbous-based trichomes. Stipules 2–3.1 × 0.5–1 mm, free, persistent, lanceolate, externally pilose with yellow vesicular glands, but lacking bulbous-based trichomes. Leaves trifoliolate; petiole 1–5.4 cm long; leaf rachis 1–2.1 cm long; stipels absent; leaflets 2,4–5.3 × 2–4.9 cm, ovate or deltoid to rhombic, surface not bullate, attenuate to acuminate at apex, obtuse or truncate at base, margin entire, pilose, with yellow vesicular glands on the abaxial surface. Inflorescence axillary, racemose, 2.7–3.5 cm long, bearing 6–9 flowers, not exceeding the length of the subtending leaf; bracts caducous; pedicels 1–1.5 mm long. Flowers 4–7 mm long excluding the pedicel; calyx 2–3.2 mm long, pubescent with yellow vesicular glands, but lacking bulbous-based trichomes, lobes lanceolate, not exceeding the corolla in length; standard petal 4–6 × 3–4.7 mm, orbicular, emarginate at apex, pilose to pubescent, with yellow vesicular glands, but lacking bulbous based trichomes, claw 1–1.5 mm long, auricle ca. 0.5 mm long; wing petals 4–5 × 1–2 mm, oblong, claw. 1.3–2 mm long, auricle ca. 0.5 mm long; keel petals 5–6 × 2–2.2 mm, falcate, claw ca. 1–2 mm long; stamens 5–5.5 mm long; ovary 2–3.3 mm long, pubescent, with yellow vesicular glands. Fruits 1.1–1.6 × 0.6–0.8 cm, reddish-brown to black, strongly constricted between the seeds, oblong, glabrescent, with yellow vesicular glands, but lacking bulbous-based trichomes. Seeds 4.7–5.5 × 3–4 mm, suborbicular, bicolored, black and red, the red confined to the hilar area.

Nomenclatural and taxonomic notes: — Rhynchosia naineckensis was described by Fortunato (1982). The type material comes from the municipality of Laguna Naineck, province of Formosa, thus the species epithet. Morphologically, it resembles R. erythrinoides and R. melanocarpa , but it is easily recognizable by the characters listed in Table 1 .

Reproductive phenology: —Flowering from February to April, and in June and September; fruiting in January to February, and from April to June and August to September.

Distribution and habitat: — Rhynchosia naineckensis occurs in Argentina, Bolivia, Brazil and Paraguay ( Fig. 13 ). It occurs in tropical and semideciduous forests and sandy and clay soil fields.

Conservation status: —Least Concern (LC). Based on an EOO of 1,393,554 km 2 (GeoCAT, accessed in May 2022), R. naineckensis is classified as LC, following the IUCN Red List criteria ( IUCN 2022). Nevertheless, the most recent record of the species was collected in 1995 and attempts to collect more specimens and to conserve the species should be made.

Selected Specimens Examined:— ARGENTINA. Corrientes: Dep. General Paz, Itá Ibate, barrancas del Paraná , 26 July 1979 (fr.), D. Medán et al. 26 ( BAA); San Cosme, May 1975 (fr.), A. Schinini & C. Quarin 115 ( CTES) .

Formosa: Formosa, Río Salado , August 1967 (fr.), A. Krapovickas 13013 ( CTES) ; BOLIVIA. Santa Cruz: Ichilo, Estância San Rafael de Amboró, ca. 30km SE of Buena Vista along the Rio Surutú , 25 August 1985 (fl./fr.), J. C. Solomon 14031 ( NY) . BRAZIL. Rio de Janeiro: Cabo Frio, Restinga de Cabo Frio , 18 November 1967 (fl./fr.), D. Sune 1927 ( RB) . São Paulo: Dracena, Estância Boa Esperança , floresta mesófila, 6 September 1995 (fr.), L. Bernacci et al. 2070 ( SP) ; Núbia, Fazenda Caramuru ( Suiços ), Vegetação em recomposição, 4 September 1995 (fr.), L. Bernacci et al. s/n. ( SP) ; Paulo de Faria , Estação Ecológica de Paulo de Faria, 19º55’S, 49º31’W, 23 August 1995 (fr.), M. D. N. Grecco et al. 83 ( SP) . PARAGUAY. L’assomption, 1845 (fr.), B. Balansa 1845 (P). San Pedro: Alto Paraguay, 28 April 1955 (fr.), A. L. Woolston 513 ( NY) . Tarija: Gran Chaco 15 kms hacia el norte de Yacuiba, 23 September 1985 (fl./fr.), Beck, Michel & Garcia 11470 ( NY) . Tavarory: Acosta ñu, 04 March 1992 (fl.), E. Zardini & T. Tilleria 30980 ( NY) .

Figures

FIGURE 13. Geographical distribution of Rhynchosia naineckensis, R. phaseoloides and R. platyphylla in South America.