Rhynchosia hauthalii (Kuntze) Grear, Mem.

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 : 32-35

12. Rhynchosia hauthalii (Kuntze) Grear, Mem. New York Bot. Gard. 20(3): 89. 1970.

Basionym: — Dolicholus hauthalii Kuntze, Revis. Gen. Pl. 3(3): 60. 1898. Type : PARAGUAY, “Sude Paraguay ”, November 1892 (fl./fr.), O. Kuntze s.n. (Neotype, designated inadvertently [as holotype] by Grear [1978]: NY 00026946 [!]). Iconography: Rodriguésia 70: 9. 2019 .

Eriosema rotundifolium Micheli, Mém. Soc. Phys. Genève 28(7): 35. 1883. Type : PARAGUAY, “Cerro Peron, prope Paraguari in pratis”, November 1876, Balansa 1538 (Lectotype, designated inadvertently [as holotype] by Grear [1978]: G [not seen]; isolectotypes: F 940492 [digital image!], K000502984 [digital image!], P 02748615, 02748616 [digital image!]).

Rhynchosia uruguaya Arechav. Anales Mus. Hist. Nat. Montevideo 3: 395. 1901. Type : URUGUAY, Tacuarembó, January 1901 (fl./fr.), Arechavaleta 1151 (Holotype: MVM [digita image!]).

Eriosema rotundifolium var. macrophyllum Chodat & Hassl. Bull. Herb. Boissier , sér. 2. 4(9): 905. 1904. Type : PARAGUAY, ‘in glareosis pr. Valenzuela ”, January 1900 (fl.) Hassler 6946 (Lectotype, first-step designated by Grear [1978]; second-step designated here: G 00400123 [digital image!]; isolectotypes: G 00400124, 00400125 [digital image!]; NY 00007876 [!]; UC 940780 [digital image!]).

Subshrub prostrate, stems not branched, pilose, indumentum light yellow, lacking vesicular glands and bulbous-based trichomes. Stipules 3–6.8 × 1–2 mm, free, persistent, lanceolate, externally pilose with sparse bulbous-based trichomes and yellow vesicular glands. Leaves trifoliolate; petiole 0,9– 2.5 cm long; leaf rachis 0.9–2 cm long; stipels persistent; leaflets 2.6–6.1 x 2.2–5.8 cm, obovate to rounded, surface not bullate, mucronate, or rounded at apex, rounded at base, margin entire, pilose, with yellow vesicular glands on both surfaces. Inflorescences axillary, racemose, 7.1–18 cm long, many-flowered, exceeding the length of the subtending leaf; bracts caducous; pedicel 1.5–2.5 mm long. Flowers 8–11 mm long excluding the pedicel; calyx 4–8.1 mm long, pubescent with yellow vesicular glands and bulbous-based trichomes, lobes lanceolate, not exceeding the corolla in length; standard petal 7–10 × 5.3–6 mm, obovate, rounded at apex, pilose to glabrescent, with sparse vesicular glands and bulbous-based trichomes, claw ca. 2 mm long, auricle ca. 0.5 mm long; wing petals 9–10 × 1–2 mm, oblong, claw 2–2.5 mm long, auricle 0.5–1 mm long; keel petals 8.5–10 × 2–3 mm, falcate, claw 2–3 mm long; stamens 8.2–11 mm long; ovary 3.3–4 mm long, pubescent, with yellow vesicular glands. Fruits 1.8–2.2 × 0.5–0.6 cm, greenish to brown, without constrictions between the seeds, oblong in outline, pubescent to hirsute, with yellow to brown vesicular glands and bulbous-based trichomes. Seeds 2.5–4 × 2.5–3.5 mm, suborbicular, unicolored, brown to black.

Nomenclatural and taxonomic notes: — Grear (1978) cited a Kuntze gathering from “Sude Paraguay ” as the holotype. Because Kuntze had studied this specimen from NY (NY 00026946), Grear (1978) inadvertently designated it as the neotype of D. hauthalii (see Turland et al., 2018, Art. 9.10).

Eriosema rotundifolium var. macrophyllum was described based on the collections Hassler 5496 and 6946. Grear’s (1978) citation of the Hassler 6946 specimen at G as the holotype constitutes an inadvertent lectotypification (see Turland et al., 2018, Art. 9.10, Ex. 11; Prado et al., 2020). Since there are two duplicate specimens of Hassler 6946 at G, Grear’s (1978) citation of the specimen G as the “ holotype ” constitutes the first step in the lectotypification of the name (see Turland et al. 2018, Art. 9.17). Thus, we designate here the specimen with barcode number G 00400123 as the second-step lectotype of Eriosema rotundifolium var. macrophyllum since it has the diagnostic characteristics most preserved.

Rhynchosia hauthalii is characterized by having prostrate stems, obovate to rounded leaflets, and racemose axillary inflorescences. It morphologically resembles R. lateritia , since they both have prostrate stems and a well-developed axillary racemose inflorescence (up to 18 cm in R. hauthalii and 21 cm in R. lateritia ). However, they are easily differentiated by their calyces (4–8.1 mm long and not exceeding the corolla in length in R. hauthalii vs. 9–10 mm long and exceeding the corolla in length in R. lateritia ).

Reproductive phenology: —Flowering in January, March to May and October to December. Fruiting in January, March to May, November and December.

Distribution and habitat: — Rhynchosia hauthalli occurs in Brazil, Paraguay and Argentina ( Fig. 9 ). Miotto (1988) recorded this species for Uruguay, but that apparent occurrence has not been confirmed in this work. The species is found in pampean environments, pastures, along roadsides, at forest edges, in grasslands, and on sandy soils.

Conservation status: —Least Concern ( LC). Based on an EOO of 286,657 km 2 (GeoCAT, accessed in May 2022), R. hauthalii is classified as LC following IUCN Red List criteria ( IUCN 2022). It is common in herbaria (especially those from southern Brazil), and is often found in conservation areas such as the Parque Nacional de Itapuã , Rio Grande do Sul, Brazil.

Selected Specimens Examined:— ARGENTINA. Corrientes: Dep. Empedrado, 13 November 1954 (fl./fr.), A. Burkart 2982 ( P); ibid., Estancia “Las Tres Marias ”, 13 November 1954 (fl./fr.), T. M. Pedersen 2982 ( NY) . BRAZIL. Paraná: Guarapuava, Cadeado , 14 December 1973 (fl.), G. Hatschbach 33529 ( MBM, NY) . Rio Grande do Sul: Alegrete, Parada Perau , 29 October 1989 (fl.), Machado & Alvarez 289 ( SMDB) ; Caçapava do Sul, BR-292, ca. 5km do acesso à cidade, 9 November 1996 (fl.), J. A. Jarenkow 3241 ( MBM) ; ibid., Irapuá, Coxilha-Alta , 30 December 1988 (fl.), L. A. Z Machado 123 ( SMDB) ; Manoel Viana ( Vila Kramer )—S. Fco. de Assis, 16 May 1991 (fr.), Machado et al. 1197 ( SMDB) ; Passo Fundo, na rodovia Marau , 4 December 1986 (fr.), J. Mattos & N. Silveira 30406 ( HAS) ; Pelotas, Fazenda do Sr. Ary Alcantara , 20 December 1962 (fl.), Barreto-Kappel 4001 ( BLA) ; Porto Alegre, Morro da Polícia , 17 April 1986 (fl./fr.), H. Janke 3 ( HAS) ; ibid., Morro Santana , 24 November 2011 (fr.), F. Schmidt-Silveira 34 ( ICN) ; ibid., s.d. (fl.), B. Rambo s.n. ( PACA) ; Santa Maria, Itagui , 18 April 1972 (fr.), Dobereiner & Tokarnia s/nº ( RB) ; ibid., Campus UFSM , 01 December 1988 (fl./fr.), L. A. Z. Machado 56 ( SMDB) ; ibid., atrás do Hospital Veterinário, na estrada em direção ao Tambo (lado direito), 25 March 1999 (fr.), E. Biondo s.n. ( SMDB) ; ibid., Distrito de Santo Antão, Morro Pedra do Lagarto , 19 November 2014 (fl./fr.), H. F. Menezes HEL021 ( SMDB) ; Santiago, Boqueirao divisa com S. Fco. de Assis , 16 January 1991 (fl.), Machado et al. 1207 ( SMDB) ; ibid., Capão do Cipó , 12 January 1991 (fl.), Machado et al. 827 ( SMDB) ; São Borja, BR 287, 14 January 1991 (fl.), Machado et al. 988 ( SMDB) ; São Francisco de Assis, a 27 km ao Norte, estrada de acesso a Santiago , 7 March 1990 (fl./fr.), L. A. Z. Machado 589 ( SMDB) ; ibid., 16 January 1991 (fr.), Machado et al. 1241 ( SMDB) ; São Gabriel, 29 May 1991 (fl.), L. A. Z. Machado et al. s.n. ( SMDB) ; Sobradinho / Manoel Viana–Itaqui , 15 January 1991 (fl.), Machado et al. 1057 ( SMDB) ; Tupanciretã, Passo da Lage , 11 January 1991 (fl./fr.), Machado et al. 780 ( SMDB) ; Viamão, Parque Nacional de Itapuã , 15 December 2005 (fr.), S. T. S. Miotto & M. S. Pereira 2271 ( ICN) ; ibid., 2 December 1984 (fr.), M. Sobral 84 ( MBM) . PARAGUAY. Itapuá: Parque Nacional San Rafael , San Pedro Mi, 14 November 2001 (fl./fr.), G. Caballero Marmori 3922 ( MBM) . Misiones: Santiago, 19 November 1956 (fl./fr.), T. M. Pedersen 4352 ( US) . 13. Rhynchosia lateritia Burkart, Legum. Argent. 2: 545. 1952. Type: — ARGENTINA, Misiones, Apóstoles , sabana quebrada, November 1943 (fr.), A. Burkart 14356 (Lectotype, designated here: SI 002517 [digital image!]; isolectotype: SI 002518 [digital image!]). Iconography: Rodriguésia 70: 9. 2019 .

Subshrub prostrate, stems simple, pilose to villous, indumentum light yellow, with sparse yellow vesicular glands, but lacking bulbous-based trichomes. Stipules 5–6 × 1–1.5 mm, free, caducous, lanceolate, externally pubescent with yellow vesicular grands, but lacking bulbous-based trichomes. Leaves trifoliolate; petiole 2.3–4.2 cm long; leaf rachis 1.2–2 cm long; stipels caducous; leaflets 3–8.5 x 1.9–5.9 cm, ovate, elliptical, obovate or rounded, surface not bullate, cuneate to rounded at apex and base, margin entire, pilose, with yellow vesicular glands on both surfaces. Inflorescences axillary, racemose, 7–21 cm long, many-flowered, exceeding the length of the subtending leaf; bracts caducous; pedicel 0.5–2.2 mm long. Flowers 7–12 mm long excluding the pedicel; calyx 9–11 mm long, pubescent, with yellow vesicular glands but lacking bulbous-based trichomes, lobes lanceolate, generally all of them equaling or exceeding the corolla in length (but sometimes slightly smaller on flowers of the same specimen); standard petal 11–12 × 6.5–8 mm, obovate, emarginate to rounded at apex, pilose, with yellow vesicular glands, but lacking bulbous-based trichomes, claw 1.5–2 mm long, auricle ca. 0.5 mm long; wing petals 10.5–11.5 × 2–3 mm, oblong, claw 2.5–3 mm long, auricle 0.5 mm long; keel petals 10–11 × 3–4 mm, falcate, claw 2.5–3.5 mm long; stamens 12.5–13.5 mm long; ovary 3.5–4.2 mm long, pubescent, with yellow vesicular glands. Fruits 1.1–2.3 × 0.6–0.8 cm, brown, without constrictions between the seeds, oblong, pilose to pubescent, with yellow vesicular glands but lacking bulbous-based trichomes. Seeds 3–4 × 3 mm, ovate, unicolored, brown.

Nomenclatural and taxonomic notes: — Rhynchosia lateritia was described by Burkart (1952) based on the gathering Burkart 14356 deposited in SI. There are two duplicates of this collection in SI (SI 002517 and SI 002518), but no particular specimen was specified as type by the author in the original publication. Therefore, we designate the specimen with barcode number SI 002517 as the lectotype of R. lateritia (see Turland et al., 2018, Art. 9.10, Ex. 11; Prado et al., 2020).

The species morphologically resembles R. hauthalii , but differs from it by the characters listed in the taxonomic notes of that species.

Reproductive phenology: —Flowering in March, October and December; fruiting in October.

Distribution and habitat: — Rhynchosia lateritia occurs in Argentina and Paraguay ( Fig. 9 ) in grassland and clay areas of Cerrado. Grear (1978) and Fortunato (1983) cited the collection Montes 3379 as being Rhynchosia lateritia from Brazil. We had the opportunity to examine this vegetative collection and consider that it is more likely a collection of R. hauthalii .

Conservation status: —Endangered (EN). Based on an EOO of 3,095 km 2 (GeoCAT, accessed in May 2022), R. lateritia is classified as EN following IUCN red list criteria ( IUCN 2022), under subcriteria, B1b (i, iii). The species was first described in 1952 and few specimens of it have been collected since.

Selected Specimens Examined:— ARGENTINA. Corrientes: Santo Tomé , 3 km SW de Gdor. Virasoro, 02 December 1981 (fl./fr.), S. G. Tressens et al. 1426 ( MEXU 339855 ) . Misiones: Candelaria, Loreto , Ruta Nac. 12, 6 October 2007 (fl.), H. A. Keller et al. 4566 ( UEC); Loreto, March 1945 (fl.), J. E. Montes 634 (SI 002519); Posadas, in graminosis prope “La Granja” prädium, 14 December 1907 (fl.), E. L. Ekman 1680 ( NY) . PARAGUAY. Paraguari: Ybytinù , 10 September 1952 (fl.), J. E. Montes 12969 (P 02748609) .

Figures

FIGURE 9. Geographical distribution of Rhynchosia hauthalii, R. lateritia, R. leucophylla and R. lineata in South America.