Rhynchosia burkartii Fortunato, Parodiana

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 : 15-17

3. Rhynchosia burkartii Fortunato, Parodiana 2: 49–52. 1983. Type:— ARGENTINA, Formosa, Dep. Matacos, pastizal entre la Florencia e Ing . G. N. Juarez, September 1980 (fl.), M. N. Correa et al. 7662 (Holotype: BAB 00000480 [digital image!]; isotypes: CTES 0000680 [digital image!], SI 002511 [digital image!]). ( Fig. 4 A–B )

Subshrub prostrate, stems branched, pubescent, indumentum light yellow, with yellow vesicular glands but lacking bulbous-based trichomes. Stipules 2–4.52 × 1–1.5 mm, free, persistent to falling late, triangular to ovate, externally pubescent with yellow vesicular glands, but lacking bulbous-based trichomes. Leaves trifoliolate; petiole 1.4–3.6 cm long; leaf rachis 0.5–1.7 cm long; stipels persistent to falling late; leaflets 1.6–3.3 × 1.1–3.6 cm, rounded, ovate, rhombic or obovate, surface not bullate, emarginate to rounded at apex, obtuse to rounded at base, margin entire, pilose to pubescent, with yellow vesicular glands on both surfaces. Inflorescences axillary or terminal, racemose or paniculate, 2.2–8 cm long, many-flowered, equaling or exceeding the length of the subtending leaf; bracts caducous; pedicel 0.5–1 mm long. Flowers 4–7 mm long excluding the pedicel; calyx 4–6 mm long, pubescent with yellow vesicular glands but lacking bulbous-based trichomes, lobes lanceolate, generally not exceeding the corolla in length (but sometimes slightly longer within the same specimen); standard petal 5–7 × 4–6 mm, obovate, rounded at apex, puberulous, pilose, or densely pilose, with vesicular glands but lacking bulbous-based trichomes, claw 1–1.5 mm long, auricle ca. 0.5 mm long; wing petals 6–6.5 × 1–1.5 mm, oblong, claw 1–1.5 mm long, auricle 0.5–1 mm long; keel petals 6–7 × 1.5–2 mm, falcate, claw 1–1.5 mm long; stamens 5–7 mm long; ovary 2–3 mm long, pubescent, with light yellow vesicular glands. Fruits 1.1–1.9 × 0.4–0.6 cm, brown, without constrictions between the seeds, elliptical, ovate, or oblong, pilose, with yellow vesicular glands but lacking bulbous-based trichomes. Seeds 2.5–2.7 × 2.3–2.5 mm, suborbicular, unicolored, brown to reddish brown.

Nomenclatural and taxonomic notes: —The epithet was selected by Fortunato (1983) to honor Dr. Arturo Burkart (1906–1975) for his dedicated studies on Leguminosae . Rhynchosia burkartii is morphologically similar to R. balansae ; the characters that differentiate the two species are given in the taxonomic notes of the latter.

Reproductive phenology: —Flowering and fruiting in February, March, May, June and October to December.

Distribution and habitat: — Rhynchosia burkartii occurs in Argentina, Bolivia, and Paraguay ( Fig. 3 ). It can be found in disturbed and recently burned areas, on sandy soils in grasslands, in semi-deciduous forests and in seasonally inundated open grassland. We examined one sheet from Brazil (MBM 260284) that was identified by Dr. Fortunato as this species. However, this collection is damaged and lacks diagnostic reproductive parts; we were thus unable to confirm the occurrence of the species in Brazil.

Conservation status: —Least Concern (LC). The estimated EOO of R. burkartii is 433,257 km 2 (GeoCAT, accessed in May 2022).

Selected Specimens Examined:— ARGENTINA. Formosa: Dep. Matacos , ruta 39, 23 km S de Ing. G. M. Juarez, 07 November 1983 (fl./fr.), R. Fortunato et al. 283 ( MBM) ; ibid., Ing. Juárez , October 1981 (fl.), A. Cabral et al. 1025 ( BAB 00000482 ) ; Dep. Patiño, 8km al N de las Lomitas , 10 November 1994 (fl./fr.), R. H. Fortunato et al. 4392 ( MBM) ; ibid., por Ruta 32, rumbo a Las Lomitas. Fn. Soledad, a 35 km hacia el N, June 1982 (fr.), A. M. Molina et al. 440 ( BAB 00000484 , 00000485 ) . Salta: Dep. Orán, Abra Grande, November 1927 (fr.), S. Venturi 7612 (US 02346644); ibid., Orán a Saucelito , February 1906 (fl./fr.), C. Spegazzini s.n. ( BAB 00000483 ) ; ibid., Ruta 50, 2km W de San Ramón de la Nueva Orán, 04 December 2005 (fr.), M. M. Arbo et al. 8974 ( MBM) ; Dep. Rivadavia , a 64 km de Gral. Mosconi, June 1982 (fl.), A. M. Molina et al. 376 ( BAB 00000486 ) . BOLIVIA. Chuquisaca: Luis Calvo, El Salvador, Laguna Seca, 08 December 1992 (fl.), J. Pensiero & G. Marino 4387 ( NY) . Santa Cruz: Chiquitos, 26 km N de San José yendo a Taperas , 11 November 1996 (fr.), A. Jardim, J. Haffman & F. Mamani 3575 ( NY) ; Cordillera, 6 Km S de Lagunillas, 19º45’ S 63º40’ W, April 1977 (fl./fr.), A. Krapovickas & A. Schinini 31421 ( CTES 0000681 ) ; ibid., around highway and railroad bridges over Rio Seco on N side of settlement of Rio Seco, along new highway from Santa Cruz to Abapó , 24 May 1998 (fl./fr.), M. Nee & L. Bohs 49457 ( NY) ; ibid., camiño hacia Boyuibe , entrando a mano derecha hacia palmarito, 10 June 2006 (fl./fr.), L. Arroyo et al. 3232 ( NY) ; ibid., Estancia Rancho Chico (puesto nuevo) y alrededores, 22 May 1998 (fl./fr.), A. Fuentes et al. 2349 ( NY) ; Velasco, aprox.. 400 m, San Ignacio 14 km hacia SE, al lado del caminho, suelo arenoso, 18 February 1988 (fl.), B. Bruderreck 249 ( NY) ; Warnes, near future “Urbanización Bélgica Chica”, 11km by dirt road E of main Highway from Santa Cruz to Warnes , 10 km (by air) SE of Warnes, 31 October 2000 (fl./fr.), M. Nee 51090 ( NY) ; ibid., pampa de Viru-viru a 17 km al N de ciudad de Santa Cruz, 13 February 1994 (fl./fr.), M. Menacho & E. Gutierrez 459 ( NY) . PARAGUAY. Boqueron: 9 km S de Loma Plata , propriedad de Ebenfeld, 25 November 1991 (fl./fr.), R. Vanni, A Radovancich & A Schinini 2174 ( NY) ; Cruce de los Pineros, 7 km NE of the Trans Chaco Highway on the road to Buenavista , 17 February 2002 (fl./fr.), M. Luckow 4487 ( NY) ; Filadelfia , 4 March 1984 (fl./fr.), W. Hahn 2140 ( MBM) ; ibid., dry thorn forest, 4 March 1984 (fl./fr.), W. Hahn 2140 ( NY) ; Nueva Asunción, between Parque Nacional Teniente Agripino Enciso and Nueva Asunción , 27 January 1995 (fl./fr.), E. M. Zardini & A. Acosta 42382 ( NY) . Chaco: Mayor Pedro Lagerenza , 20º S 60º45’ W, April 1978 (fl./fr) A. Schinini & E. Bordas 14888 ( CTES 0000682 ) .

Figures

FIGURE 3. Geographical distribution of Rhynchosia arenicola, R. balansae, R. burkartii and R. caagazuensis in South America.

FIGURE 4. Detailed structures of Rhynchosia species. A–B. Portion of the stem and detail of fruit of R. burkartii. C. Stem of R. caaguazuensis showing the leaflets shape and inflorescences. D–E. Fruit of R. erythrinoides. F, G. Portion of the stem and detail of fruit of R. mantaroensis var. cuprinervia. (Illustrated by Klei Souza).