Rhynchosia balansae Micheli, Mém. Soc. Phys. Genève, 1883

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 : 13-14

2. Rhynchosia balansae Micheli, Mém. Soc. Phys. Genève 28(7): 31. 1883.

Dolicholus balansae (Micheli) Kuntze , Revis. Gen. Pl. 3(3): 60. 1898. Rhynchosia reticulata fo. balansae (Micheli) Hassl., Repert. Spec. Nov. Regni Veg. 16: 230. 1919. Type:— PARAGUAY, “Assomption, in collibus incultis”, February 1874 (fl./fr.), B. Balansa 1513 (Lectotype, designated inadvertently [as holotype] by Grear [1978]: G 00400128 [digital image!]; isolectotypes: F 935567 [digital image!], K 000502955[!], LE 00002542 [digital image!], P 00708587[!], S R-9721 [digital image!]). Iconography: Rodriguésia 70: 5. 2019. ( Fig. 2 D–E )

Rhynchosia pallida Micheli, Mém. Soc. Phys. Genève 28(7): 32. 1883. Rhynchosia schomburgkii fo. pallida (Micheli) Hassl., Repert. Spec. Nov. Regni Veg. 16: 230. 1919 . Type: PARAGUAY, “Cerro-Peron prope Paraguari in pratis”, January 1876 (fr.), B. Balansa 1511 (Lectotype, first-step designated by Grear [1978]; second-step designated here]: P 00709013 [digital image!]; isolectotypes: K 000502963 [digital image!], P 00709012 [digital image!]). syn. nov.

Rhynchosia hagenbeckii Harms, Bot. Jahrb. Syst. 33, beibl. 72: 29. 1903. Type: ARGENTINA, Gran Chaco, Hagenbeck s.n. (Holotype: B [not seen]; isotype: F 0059816F [fragment; [digital image!]]).

Rhynchosia hassleriana Chodat, Bull. Herb. Boissier , sér. 2. 4(9): 904. 1904. Type: PARAGUAY, “in campo pr. flumen Jejui guazu, s.d. (fl.) E. Hassler 5692 (Lectotype, designated inadvertently [as holotype] by Grear [1978]: G 00400134 [digital image!]; isolectotypes: F 1563549 [digital image!], GH 00063821 [digital image!], K 000502956 [digital image!], MPU 022975 [digital image!], NY 00026945[!], P 00708604 [digital image!], UC 934983 [digital image!]).

Rhynchosia pallida var. boliviana Grear, Mem. New York Bot. Gard. 31(1): 145–147.1978. Type: BOLIVIA, “Chiquitos”, s.d. (fl./fr.), A. D. d’Orbigny 832 (Holotype: P 00709011 [digital image!]; isotypes: BAB [fragment] 00000491 [digital image!], G 00370857 [digital image!]). syn. nov.

Rhynchosia balansae var. psilantha Fortunato, Parodiana 2: 56–57, f. 4. 1983. Type: ARGENTINA, Corrientes, Dep. Concepcíon , 28 km SE de Concepción Ea. El Tránsito, May 1976 (fl.), A. Schinini et al. 13037 (Holotype: CTES 0000671 [digital image!]; isotype: SI 002510 [digital image!]). syn. nov.

Subshrub erect to prostrate, stems simple to few-branched, pubescent, indumentum light yellow to yellow, with yellow vesicular glands, but lacking bulbous-based trichomes. Stipules 2.3–5 × 1–2.1 mm, free, caducous, ovate or lanceolate to triangular, externally pubescent with yellow vesicular glands but lacking bulbous-based trichomes. Leaves trifoliolate; petiole 1.2–3.4 cm long; leaf rachis 0.5–1.5 cm long; stipels falling late; leaflets 2.5–8.5 × 0.9–3.2 cm, narrowly elliptical to elliptical or oblong, surface not bullate, cuneate to rounded at apex, truncate, subcordate or rounded at base, margin entire, pubescent to tomentose, with yellow vesicular glands predominantly on both surfaces, rarely just on the abaxial. Inflorescences axillary, racemose, 4.5–12 cm long, many-flowered, equaling or exceeding the length of the subtending leaf; bracts caducous; pedicel 0.5–1 mm long. Flowers 5.5–9 mm long excluding the pedicel; calyx 4–8.5 mm long, pubescent with yellow vesicular glands but lacking bulbous-based trichomes, lobes lanceolate, all of them equaling or exceeding the corolla in length; standard petal 4.5–6.7 × 3–4 mm, elliptical or oblong, rounded at apex, pilose, with yellow vesicular glands but lacking bulbous-based trichomes, claw 0.5–1 mm long, auricle 0.3–0.5 mm long; wing petals 4.5–6.2 × 1–1.3 mm, oblong, claw 1–1.5 mm long, auricle ca. 0.5 mm long; keel petals 4.5–6.3 × 1.3–2 mm, falcate, claw 1–1.5 mm long; stamens 3.7–6 mm long; ovary 1.5–3 mm long, hairy, with yellow vesicular glands. Fruits 1–1.5 × 0.5–0.6 cm, green to brown, without constrictions between the seeds, ovate, oblong, or elliptical, pubescent to tomentose, with yellow vesicular glands but lacking bulbous-based trichomes. Seeds 3–4 × 2.5–3.8 mm, suborbicular, unicolored, brown to black.

Nomenclatural and taxonomic notes: — Fortunato (1983) characterized R. balansae var. psilantha by the stems prostrate (vs. erect to prostrate in R. balansae var. balansae ), the standard petal glandular and glabrous or rarely pubescent at the apex (vs. glandular-pubescent), with the apex emarginate (vs. apiculate to rounded), the wings glabrous (vs. glandular-pubescent), and the calyx with long and short trichomes (vs. puberulous or with long and short trichomes). After a careful comparison of images of the type collection of Fortunato’s variety with material of the typical variety we concluded that the purported diagnostic characters display overlapping variation between the two taxa. Therefore, we propose the synonymization of R. balansae var. psilantha under R. balansae .

Rhynchosia pallida and R. balansae were described by Micheli (1883) based on two collections from the same expedition in Paraguay: Balansa 1511 and 1513, respectively. The distinction between the two taxa was based on purported differences in the orientation of the stems (erect in R. pallida vs. prostrate in R. balansae ), the length of the calyx lobes (slightly longer in R. pallida ), the spacing of flowers on the racemes (more congested in R. balansae ), and the distribution of vesicular glands on the leaflets (present on both surfaces in R. pallida vs. only on the abaxial surface in R. balansae ). The two species were subsequently recognized by Grear (1978) and Fortunato (1983) based on the same distinguishing characters. However, in our analysis of specimens, including digital images of type specimens, we observed essentially continuous variation in the distinguishing characters. Therefore, R. pallida is proposed here as a synonym of R. balansae .

Micheli (1883) did not specify a particular specimen as the type of R. pallida from among the duplicates of Balansa 1511. Grear (1978) subsequently cited material of the type gathering in P as the holotype. However, since there are two duplicates of the collection deposited in P, it was necessary here to make a second step in the lectotypification of R. pallida (see Turland et al. 2018, Art. 9.17).

Rhynchosia balansae is characterized by narrowly elliptical to elliptical or oblong leaflets ( Fig. 2 D–E ) with vesicular glands on both surfaces and by the racemose inflorescences equaling or exceeding the length of the subtending leaf. It is morphologically similar to R. burkartii , particularly in fruits characteristics. However, it differs from R. burkartii by its narrowly elliptical to elliptical or oblong leaflets (vs. rounded, ovate, rhombic or obovate in R. burkartii ; Fig. 4A ); the calyx lobes equaling or exceeding the corolla in length (vs. not exceeding or occasionally also slightly longer within the same specimen), and the inflorescence racemose (vs. racemose or paniculate).

Reproductive phenology: —Flowering and fruiting mainly from January to March and October to December (rarely flowering in August).

Distribution and habitat: — Rhynchosia balansae occurs in Argentina, Bolivia, Brazil, Paraguay and Uruguay ( Fig. 3 ). This species can be found in secondary vegetation, open cerrado areas, seasonally deciduous forests, along roadsides and in pastures.

Conservation status: —Least Concern (LC). The estimated EOO of R. balansae is 571,848 km 2 (GeoCAT, accessed in May 2022).

Selected Specimens Examined:— ARGENTINA. Corrientes: Capital , 15 February 1996 (fl.), A. Schinini 30430 ( UEC) ; Dep. Concepción, Estancia Tranquera de Hierro, 66 km al NE de Chavarria, camino a Concepción ; Cerro Puitá , 14 km al E de la ruta, aprox 28 35’S 58 04 W, 3 December 1996 (fl./fr.), M. M. Arbo, S. A. Cáceres & V. Maruñak 6933 ( NY) ; Dep. Empedrado, Arroyo Gonzalez y Ruta 12, 27 February 1974 (fl./fr.), C. Quartin et al. 2273 ( MBM) ; Dep. General Paz, Los Cubanos , 7 December 1944 (fl./fr.), G. J. Schuvarz 300 ( NY) . Dep. San Miguel , 12 km NE de San Miguel, 1 March 1990 (fl.), R. Vanni et al. 1552 ( NY) ; Dep. San Roque, Chavarria —cercanias, 2 April 1945 (fr.), F. Ibarrola 2831 ( NY) . BOLIVIA. Santa Cruz: Chiquitos, camiño Roboré- San José, 7 km NW de Roboré, camiño de la serrania, s.d. (fl.), B. Mostacedo & R. Abboutt 2851 ( NY) . BRAZIL. Mato Grosso do Sul: Aquidauana , 19 February 1970 (fr.), G. Hatschbach 23814 ( MBM) ; ibid., 30 July 2013 (fl.), A.L.B. Sartori et al. 709 ( BOTU) ; Bela Vista, Córrego Capei , 17 March 1985 (fl./fr.), G. Hatschbach & J. M. Silva 49188 ( MBM, NY) ; ibid., Rodovia Bela Vista–Caracol , km 117, 06 September 2016 (fl.), P. H. A. Melo & G. M. Marcusso 5705 ( HUEFS) ; Bonito , MS - 382, 6, 5 km E de Bonito, 21º05’15’’S 56º35’35.6’’ W, alt. 423, 09 November 2002 (fl./fr.), A. Pott et al. 10529 ( RB) ; ibid., Rodovia Bonito ao trevo com a Rod. BR-267, próximo do km 31, 13 November 2002 (fl.), G. Hatschbach et al. 74176 ( MBM) ; ibid., 11 March 2003 (fl.), G. Hatschbach et al. 74524 ( MBM) ; ibid., Rodovia Guia Lopes da Launa a Bonito, Rio Miranda , 09 March 2003 (fl./fr.), G. Hatschbach et al. 74404 ( MBM) ; Caracol , 10-20 km 0, 24 October 1987 (fl.), G. Hatschbach et al. 51638 ( MBM) ; 15 km L na rod. para Bela Vista , 10 February 1993 (fl.), G. Hatschbach et al. 58871 ( MBM) ; Corumbá, Fazenda Leque , 01 October 1976 (fl./fr.), A. Allen 16 ( RB) ; ibid., Fazenda Santa Cruz, 20 November 2002 (fl./fr.), G. Hatschbach et al. 73925 ( MBM) ; Maracaju, Rod. BR-163, descida para a Serra de Maracaju , 08 October 2003 (fl./fr.), G. Hatschbach et al. 76027 ( MBM / RB) . PARAGUAY. Paraguari: Acahay , 27 January 1992 (fl./fr.), E. Zardini & P. Aquino 29981 ( NY) . “ Assomption , in collibus incultis”, October 1875 (fl./fr.), B. Balansa 1844 (P 02749401). Conceptión: 3, 2 km NW de Loreto, camino a Valle-Mi, 03 March 2009 (fl./fr.), M. Dematteis et al. 3129 ( UEC) ; In regione collium, Cordillera de Villa-Rica, 1905 (fl./fr.), M. Hassler 8727 (P); Ybycui , 12 March 1992 (fr.), E. Zardini & L. Guerrero 30996 ( NY) . URUGUAY. Montevideo: January 1873 (fl.), Fruchard 1022 (P) .

Figures

FIGURE 2. Rhynchosia species. A–C. R. arenicola. D, E. R. balansae. F. R. claussenii. G–J. R. corylifolia. (A–C, G–J by T.C. Monteiro); (D, E by R. Ripley) and (F. by C. Martins).

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).