Discolobium pulchellum Benth. (1837: 42)

Sartori, Ângela Lúcia Bagnatori, Neves, Ianny Marques, Seleme, Elidiene Priscila & Mansano, Vidal De Freitas, 2017, A taxonomic revision of the South American genus Discolobium (Leguminosae, Papilionoideae), Phytotaxa 308 (1), pp. 1-19 : 12-18

5. Discolobium pulchellum Benth. (1837: 42) . Lectotype (designated here):— BRAZIL, s/d, Schüch 98 F (photo!),

isolectotype W0031719!). Figure 5 .

= Discolobium elongatum Benth. (1859: 73) , syn. nov. Lectotype (designated here):— PARAGUAY, May 1845, M. A. Weddell 3196 (P02936293 (photo!), isolectotype P02936294!).

= Discolobium pulchellum var. major ( Moore 1895: 343) , syn. nov. Lectotype (designated here):— BRAZIL, Mato Grosso, 1891–92, S. Moore s/n (BM000931731!).

= Discolobium paucijugum Harms ex Kuntze (1898: 60) , syn. nov. Lectotype (designated here):— PARAGUAY, Vila Florida, November 1892, Harms s/n (F2131 (photo!), isolectotypes NY00007777 (photo!), US00001950!).

= Discolobium pulchellum var. viscosissimum Hassler (1910: 125) , syn. nov. Lectotype (designated here):— PARAGUAY, Alto Paraguai, Chaco, 1906, K. Fiebrig 1214 (G00306254 (photo!).

Subshrub erect, 1–3.5 m tall, branch grayish or dark brown, hirsute, apex velvety, branch and petiole with glandular trichomes; leaf 8.5–30 cm long, petiole 3–4.5 cm long, sparsely sericeous, ventrally canaliculate, rachis grooved, petiolule 1.4–1.9 mm long, velvety, base horizontally grooved, stipules lateral, 5–6.5 mm long, persistent or caducous, linear or lanceolate-linear, apex acute, base truncate, sericeous, trichomes on margins; (7–)9–15(–17) leaflets, elliptical, apex rounded, mucronulate, base acute, opposed or sub-opposed, margin same color as blade, 1.5–7 × 0.25–1.3 mm, concolorous, adaxial surface glabrous, abaxial surface puberulent to densely sericeous, main vein emerged on abaxial surface, secondary venation immersed, densely pilose; inflorescence 20–37.5 cm long, stem hirsute, glandulous, apex velvety; bract 5.5–5.7 mm long, ovate-lanceolate, apex acute, aristate, base truncate, externally pubescent, glandular trichomes sparse; flowers 2–3 cm long, pedicel 0.5–1 cm long, hirsute, glandular trichomes all along its length; bracteoles ca. 4.5 mm long, lanceolate-linear, apex acute, base truncate, sericeous, trichomes on margins; calyx 7.75 mm long, sparsely sericeous externally, glabrous internally, dorsal lacinia obtuse, fused on ca. 4/5 of their length, ventral lacinia acute, fused on ca. half of their length; vexillum large-oboval, apex obcordate, base unguiculate, 11 × 10.7 mm, claw 1.8 mm long; wings obovate 10.3 × 4.5 mm, claw 2.6 mm long; keel petals falciform 7.4 × 3.5 mm, claw 2.6 mm long; stamens 5.4–6.8 mm long, anther elliptic, 1.4 × 0.8 mm; gynoecium 9.1 mm long, ovary 2.1 mm long, ciliated, stipe 1.8 mm long, ciliated on distal portion, style 5.2 mm long, stigma punctiform. Fruit with seminiferous region sparsely tuberculate on margin, sinuated fruit margin; upper whorl ca. 3–6 mm in width, middle whorl 13–19 mm in width, lower whorl imperceptible under the calyx persistent.

Distribution and habitat:— Discolobium pulchellum is widely distributed and reported in Argentina, Paraguay, and Brazil, in floodable areas of the Pantanal and Chaco regions, in tropical ombrophilous alluvial forests; medium height herbaceous vegetation, practically without woody vegetation, dry or flooded most of the year and on river banks ( Figure 8 ).

Phenology:—Flowers all year round, fruits in October and from December to August.

Distinguishing features:— Discolobium pulchellum is considered the most polymorphic species of the genus since it presents morphological variations in a single specimen or in plants at different developmental stages. It is distinguished from the other species by its 7–17-foliolate leaves, elliptical, discolorous leaflets, calyx with obtuse dorsal lacinia, fused on ca. 4/5 of their length and acute ventral lacinia fused on ca. half of their length, falciform keel petals, and fruits with sinuous margins.

Discolobium elongatum had already been treated by Burkart (1939) as a synonym of D. pulchellum var. viscosissimum . D. paucijugum and D. pulchellum were considered distinct based on the superposition of indumentum features or types, here considered as variable characteristics, thus minimally reliable. The present study proposes to synonymize Discolobium elongatum , Discolobium paucijugum , Discolobium pulchellum var. viscosissimum , and Discolobium pulchellum var. major with D. pulchellum because the type specimens observed together with other materials show that these morphological variations do not justify delimiting distinct taxa.

According to its description, D. paucijugum usually presents seven leaflets, a feature compatible with D. pulchellum , although it is less frequent. D. pulchellum var. major has been described based on such few features as leaflet and flower measures, but such characters are similar to those of D. pulchellum and are inadequate to establish a major variety.

According to Hassler (1910), variety viscosissimum relied mainly on the indumentum with glandular trichomes and on the leaflet number, attributes that can vary on the same plant, as our observations have shown. Such features had already been reported by Bentham (1837) in his description of D. pulchellum , which justifies the synonymization proposed here.

Specimens examined:— ARGENTINA. Chaco: Puerto Bermejo , 07 March 1901, Kermes 662 ( INTA) ; Formosa: s/l, September 1918, P. Jórgensen 3110 ( LIL) ; Las Delicias , 08 January 1947, A. Reales 118 ( LIL) ; Pilcomayo , ao sul de Clorinda, 29 August 1946, I. Morel 1132 ( LIL) ; Pilcomayo, Costa do rio Paraguai a aproximadamente 4 Km do Porto da Prefeitura Bouvier em direção norte, 25 March 1993, R. H. Fortunato et al. 4019 ( CTES, INTA) ; Pilcomayo, Isla Laguna , 04 September 1944, T. Rojas 12214 ( LIL) ; Pilcomayo, Loma Porá , 09 December 1946, I. Morel 1808 ( LIL) . BRAZIL. s/l, Fazenda Santa Izabel , 09 October 1979, A. Allem & G. Vieira 2589 ( HUEFS, NY) ; s.l., s.d., Schuech 98 ( NY) ; Mato Grosso do Sul: s/l, próximo ao Rio Negro , 22 October 1980, Paschoal 43 ( HRB, RB) ; Aquidauana, Pantanal , 28 January 1979, A. Fernandes & P. Bezerra s.n. ( EAC 5248 ) ; Corumbá , 02 July 2007, A. P. Oliveira et al. 07 ( CGMS) ; Corumbá, Base de Pesquisas UFMS, 02 November 1992, U. M. Resende 803 ( CGMS) ; Corumbá, Campo inundável próximo a margem do Rio Bracinho , 23 July 2009, R. H. Silva 48 ( CGMS) ; Corumbá, Estrada Parque , 08 February 2007, M. L. Bueno et al. 490 ( CGMS) ; Corumbá, Estrada Parque , 25 July 2006, J. S. Garcia et al. 14 ( CGMS) ; Corumbá, Fazenda Bodoquena , 28 October 1978, A. C. Allem et al. 2229 ( NY) ; Corumbá, Fazenda Leque , 19 August 1991, A. C. Cervi et al. 3348 ( CPAP, MBM, UPCB) ; Corumbá, Fazenda Porto Belo, Baía do Castelo , 29 July 1986, A. Rego 642 ( COR) ; Corumbá, Fazenda Três Alziras, Rod. MS 454 a 27 km da Rod. BR 262, Jacadigo , Pantanal , 27 May 1992, V. J. Pott et al. 1684 ( CPAP, R) ; Corumbá, Porto Esperança , September 1914, G. Kuhlmann 395 (R) ; Corumbá, próximo a Ilha do Sargento , 30 July 1982, J. E. de Paula & C. A. Conceição 1571 ( IBGE) ; Corumbá, Rio Paraguaimirim , 03 April 2009, F. S. Carvalho et al. 167 ( CGMS) ; Corumbá, Rio Taquari , 03 April 1983, C. A. Conceição 1303 ( CGMS, IBGE) ; Corumbá, Leque , 10 November 1977, I. A. Rodrigues et al. 382 ( RB) ; Miranda, Rio Miranda , 13 May 1976, G. Hatschbach 38630 ( MBM) ; Miranda, Rod. BR 262 próximo ao Rio Miranda , 14 May 1972, G. Hatschbach 29467 ( MBM, MO) ; Miranda, Rod. Miranda—Corumbá Km 668, 18 June 2006, J. M. Silva & E. Barbosa 4994 ( MBM) ; Miranda, 90 Km oeste de Miranda, Morro do Azeite , 28 January 1979, A. Krapovickas & C. L. Crisóbal 34454 ( MBM) ; Porto da Manga, Pantanal , 25 September 1982, O. L. Peixoto & G.M. Barroso 1708 ( RB, UEC) ; Porto Murtinho, 18 March 1985, G. Hatschbach & F. J. Zelma 49226 ( CEPEC, CPAP, MBM, MO, W), Porto Murtinho, Fazenda Quebracho-Brasil , 03 October 2012, A.L.B.Sartori et al. 1114 ( CGMS) ; Rio Apa , 22°04’56”S, 57°58’56”W, 24 March 1998, H. C. Lima 5565 ( CEN, RB) ; Porto Murtinho , 21°30’15”S, 57°29’31”W, 24 May 2013, V. A. Assunção 723 ( RB) ; Porto Murtinho , 21°46’48”S, 57°54’37”W, S. M. de Faria et al. 1437 ( RB) ; Mato Grosso: s.l., Fazenda Baia, 01 October 1977, G. Schaller 45 ( NY) ; s.l., Fazenda Jofre, Transpantaneira , 15 October 1978, G. Schaller 492 ( NY) ; Cuiabá , 1827, L.Riedel s.n. ( NY 1056226 ) ; s/l, Estrada Transpantaneira, Acampamento do Exército , 28 January 1979. E. P. Heringer et al. 878 ( IBGE, NY, RB) ; Barão de Melgaço , 16°39’53”S, 56°17’52”W, 26 May 2015, G. Matinelli et al. 18611 ( RB) ; Poconé , 17 March 2004, G. A. Lima Jr & H. Ferreira 253 ( UFMT) ; Poconé, a 20 Km do Rio Cassangé na estrada MT 060, 26 October 1985, W. Thomas et al. 4631 ( INPA, NY) ; Poconé, Retiro Santa Isabel, Fazenda Porto Jofre , Pantanal sub-região de Poconé, 05 October 1989, A. Pott 5012 ( CPAP) . PARAGUAY. s/l, s/d, Hassler 7177 (BM, K, LIL, P, W) ; s/l, Pelas margens do Rio Salado , March 1916, Rojas 1653 ( LIL) ; Alto Paraguai: Puerto Gaurani , 17 October 1947, T. Rojas 13608 ( LIL) ; Capital: Ita Enramada , 29 March 1981, A. Schinini 21038 ( CTES) ; Central: Tavarory , 12 August 1993, E. M. Zardini & L. Guerrero 36867 ( BAB) ; Urbanização Acosta Ñú, entre San Antonio e Ytororó , 08 May 1994, A. Krapovickas et al. 45214 ( LIL) ; Concepción: Itapucumi , 19 September 1893, Malme 966 ( BM, R) ; PILAR: Humaitá , 09 December 1950, T. Meyer 16175 ( LIL) ; Humaitá , 12 December 1950, A. G. Schulz 7778 ( LIL) ; Presidente Haynes: Colônia Indígena , 15 december 1950, G. J. Schwarz 11030 ( LIL) ; Estancia Santa María del Doce , 05 March 2006, J. De Egea Juvinel et al. 966 ( BM) ; Margem do alto Paraguai, frente a Puerto Risso , 18 January 1955, T. Meyer & A. G. Schulz 18509 ( LIL) .

6. Discolobium tocantinum ( Ducke 1922: 143) . Lectotype (designated here):— BRAZIL, Pará, Rio Tocantins, Arapary , 08 July 1916, A. Ducke 16212 (MG16212!, isolectotypes: BM000931730!, BR3200407, F, R000002393!, RB00540252!, US00001949!). Figure 6 .

Subshrub erect, ca. 1 m tall, branch chestnut brown, canescent, velvety, glandular trichomes absent; leaf ca. 4–6 cm long, petiole 1.5–3 cm long, canescent, velvety, petiole ventrally canaliculate, rachis not grooved, petiolule 1–2 mm long, velvety, stipules lateral, ca. 4 mm long, persistent, linear-triangular, apex acute, base truncate; 5(–7) leaflets, oblong to elliptical, apex rounded, mucronulate, base acute, opposed, margin same color as blade, terminal leaflets slightly longer than lateral ones (ca. 1 cm) ca. 25 mm × 7 mm, discolorous; adaxial surface glabrous, abaxial surface sparse canescent, main vein emerged on abaxial surface, secondary venation immersed, densely pilose; inflorescence up to 15 cm long, stem canescent; bracts ca. 3 mm long, lanceolate, apex acute, base truncate, sericeous; flowers ca. 1.7 cm long, pedicel ca. 0.5–1 cm long, bracteoles ca. 2 mm long, lanceolate, apex acute, base truncate; calyx ca. 8 mm long, glabrous, dorsal lacinia rounded, ventral lacinia accuminate, both fused on ca. 3/4 of their length; vexillum large-elliptic to suborbicular, apex retuse, base unguiculate, 12 × 7 mm, claw 2.5 mm long; wings obovate, 12 × 4 mm, claw 4 mm long; keel petals obovate, 7.5 × 3 mm long, claw 2.5 mm long; stamens ca. 7–8 mm long, anther elliptic, 1 × 0.5 mm; gynoecium 7 mm long, ovary 2 mm long, glabrous, stipe 2 mm long, glabrous, style 3 mm long, stigma punctiform; immature fruit (not described).

Distribution and habitat:— Discolobium tocantinum occurs exclusively in the State of Para, Brazil, in floodable areas of the Tocantins River among stones or on banks ( Figure 8 ).

Phenology:—Presents flowers and fruit in July. Very likely a rare species since only the type specimen has thus far been registered.

Distinguishing features:— Discolobium tocantinum differs from the other species mainly by its canescent indumentum and dorsal and ventral calyx lacinia with a similar degree of fusion, in addition to its short inflorescence, with stems up to 15 cm long.

Specimens examined:—This species is known only by the type collection.

Figures

FIGURE 5. Discolobium pulchellum Benth. A. Branch with inflorescence, buds and flowers. B. Leaflet. C. Bract. D. Bracteole. E. Calyx. F. Vexillum. G–H. Wing. I–J. Keel petals. K.Androecium. L. Gynoecium. M. Fruit with sinuous margin. (A–L from R. H. Silva 98 (CGMS); M from A. Pott 5012 (CPAP))

FIGURE 6. Discolobium tocantinum Ducke. A. Branch with leaf and inflorescence. B. Leaflet. C. Bract. D. Bracteole. E. Calyx. F. Vexillum. G–H. Wing. I–J. Keel petals. K. Androecium. L. Gynoecium. (A–M from A. Ducke 16212 (RB))

FIGURE 8. Geographical distribution of species of Discolobium in South America: ▲ Discolobium psoraleaefolium, ● Discolobium pulchellum, ■ Discolobium tocantinum.