Discolobium junceum Micheli (1889: 80

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 : 6-12

2. Discolobium junceum Micheli (1889: 80 ; Tabula XXIV). Lectotype (designated here):— PARAGUAY, Balansa

3089 (F28076 (photo!), isolectotype G00306262!). Figure 2 .

= Discolobium leptophyllum var. junceum (Micheli) Hassl. (1910: 68) , syn. nov. Lectotype (designated here):— PARAGUAY, wet grassland by lower Pilcomayo River , Rojas 380 (F G00306215!).

= Discolobium leptophyllum var. junceum f. grandiflora Hassl. (1910: 126) , syn. nov. Lectotype (designated here):— PARAGUAY, Pilar , Loma Clavel, Gran Chaco, 23°20’S, November 1903, E. Hassler 2579 ( LIL393542 !, isolectotypes K! FG00306249! NY00007776! P02936292! RB00175976! US00001951! W19060001172!).

= Discolobium leptophyllum var. junceum f. parviflora Hassl. (1910: 126) , syn. nov. Lectotype (designated here):— PARAGUAY, wet grassland by lower Pilcomayo River , Rojas 380 (FG00306215!).

Subshrub erect, ca. 0.6–0.8 m tall, branch chestnut brown, subglabrous to sericeous, glandular trichomes absent; leaf rarely present 3–6.5 cm long, petiole 1.5–2 cm long, sericeous, ventrally canaliculate, rachis grooved, petiolule 1.2–1.8 mm long, velvety, base horizontally not grooved, stipules lateral, ca. 3 mm long, persistent, linear or linear-triangular, apex acute, base truncate, hirsute, glandular trichomes sparse; 3(–5) leaflets, elliptical or oblong, apex rounded, mucronulate, base acute to rounded, opposed or sub-opposed, margin same color as blade, 5–12.5 × 3.5–6.5 mm, discolorous, adaxial surface glabrous, abaxial surface sparsely sericeous, glandular trichomes absent, main and secondary venations emerged on the abaxial surface, main vein densely pilose; inflorescence 35–55 cm long, stem sparsely sericeous; bracts ca. 3 mm long, ovate-lanceolate, margins green, apex acute, base truncate, sparsely sericeous externally; flowers ca. 1.5 cm long, pedicel ca. 0.6 cm long, sericeous all along its length, glandular trichomes absent; bracteoles 2–2.6 mm, lanceolate-linear to triangular, apex acute, base truncate, sparsely sericeous, glandular trichomes absent; calyx sparsely sericeous externally, glabrous internally, dorsal lacinia obtuse, fused on 5/6 of their length, apex dorsally expanded, ventral lacinia lateral with apex acute and central ones with apex rounded, fused on half of their length; vexillum suborbicular, apex obcordate, base unguiculate, 7.5 × 7.6 mm long, claw 1.4 mm long; wings obovate 7.2 × 3.5 mm, claw 1.3 mm long; keel petals obovate 5× 2.7 mm, claw 1.4 mm long; stamens 4.7–6.3 mm long, anther 0.9 × 0.4 mm; gynoecium 6.7 mm long, ovary 1.7 mm long, ciliate, stipe 1 mm long, ciliate on distal portion, style 4 mm long, glabrous, stigma clavate. Fruit with seminiferous region sparsely to densely tuberculate on margins; upper whorl 3–7 mm in width, sometimes rudimentary; middle whorl 15–19 mm in width, lower whorl 7.5–12.5 mm in width.

Distribution and habitat:— Discolobium junceum occurs in Argentina, in the provinces of Corrientes and Formosa, and in Paraguay, in the departments of Misiones, Pilar, and President Hayes, in floodable areas with medium height herbaceous vegetation and evergreen trees or with medium height herbaceous vegetation, practically without woody vegetation, dry or flooded most of the year ( Figure 7 ).

Phenology:—Flowers from January to May and fruits from February to May.

Distinguishing features:— Discolobium junceum is characterized by its typical 3-, rarely 5-foliolate leaves, elliptical or oblong leaflets, calyx with obtuse dorsal lacinia and lateral ventral lacinia with acute apex and central ones with rounded apex.

Burkart (1939) proposed to synonymize D. junceum and D. leptophyllum var. junceum with D. leptophyllum based on the type material, Balansa 3089 (F), which seems to have 1-foliolate leaves. Nevertheless, D. junceum presents 3-foliolate leaves, as shown by the scar left after leaflets fall, and its leaflets are shorter than 1 cm. Such features are not in line with the delimitation of D. leptophyllum . In this study, D. junceum is considered as a distinct taxon, with 3-rarely 5-foliolate leaves, brochidodromous venation and main and secondary veins emerged on abaxial surface.

Since Hassler may have made a mistake when he considered D. junceum as a variety of D. leptophyllum , we propose to synonymize D. leptophyllum var. junceum with D. junceum based on the above-mentioned differences in venation and in the length of terminal leaflets seen in these taxa.

After analyzing the type material of D. leptophyllum var. junceum f. grandiflora , we verified that its morphology and number of leaflets fit into the delimitation of D. junceum , which prompted us to synonymize this form.

According to the original description, the distinctive features of D. leptophyllum var. junceum f. parviflora are the form of its bracteole and the measures of flower parts in millimeters. Yet these characters overlap those of the above-mentioned taxa and, therefore, were not considered consistent enough to maintain D. leptophyllum var. junceum f. parviflora . In addition, when he described the form parviflora, Hassler (1910) used a specimen he had already mentioned in the description of D. leptophyllum var. junceum , which created an inconsistency in the infraspecific category he proposed.

Specimens examined:— ARGENTINA. Corrientes: San Luis del Palmar, Rota 5, a 18 Km de San Luis del Palmar , 02 November 1979, R. Vanni et al. 106 ( LIL, MBM) ; Formosa: s/l, s/d, C. Spegazzini 10155 ( LIL) ; s/l, 1918, P. Jórgensen 2691 ( LIL, MO) ; Formosa, borda da Rota 11 nos limites Depto Pilcomayo , 09 November 1986, A. Charpinez & U. Esleuche 2489 (G, MO) ; Parque Nacional de Pilcomayo , 09 November 1991, R. H. Fortunato et al. 2010 ( INTA) ; Pilcomayo, Ruta 11 Km 101, 29 November 1947, I. Morel 4268 ( LIL) ; Misiones: Capital, Posadas , Arroio Zaimán , 24 November 1993, I. Lirussi & A. Cardoso 531 ( INTA) . PARAGUAY. s/l, 05 February 1945, T. Rojas 12521 ( LIL) ; s/l, Estancia Loma Porá, Chaco , V.1917, T. Rojas 2890 ( LIL) ; Misiones: Santiago, Estancia La Soledad , 21 October 1959, T. M. Pedersen 5182 (C, K, P) ; Presidente Haynes: Pozo Colorado — Asunción, 104 Km de Pozo Colorado , 19 November 1993, E. M. Zardini & L. Guerrero 37566 ( INTA) .

3. Discolobium leptophyllum Benth. (1859: 72) . Lectotype (designated here):— BRAZIL, Salinas , May 1844, M.A. Weddell 2162 (P02936290 (photo!). Figure 3 .

Subshrub erect, 0.6–2 m tall, branch dark brown, pubescent, apex velvety, trichomes hirsute-hirtellous, sparsely glandular; leaf 9–18 cm long, petiole 2–3 cm long, sparsely sericeous, glandular trichomes sparse, ventrally canaliculate, rachis grooved, petiolule ca. 2 mm long, velvety, base horizontally grooved, stipules lateral, ca. 4.5 mm long, caducous, rarely persistent, lanceolate, apex acute, aristate, base truncate, sericeous, trichomes on margins; (1–3–)5–9(–11) leaflets, rarely one leaflet only, when present located at branch base, oblong-linear, collective vein prominent, apex rounded, mucronulate, base acute, opposed, margin entirely reddish to blackened, terminal leaflets two to three times longer than lateral ones, (5.5–)8(–14) × 0.5 mm, lateral ones 4 × 0.3 cm, discolorous, adaxial surface glabrous, abaxial surface puberulent to sparsely sericeous, glandular trichomes present, main vein emerged on abaxial surface, densely pilose; inflorescence 20–70 cm long, stem hirsute, glandulous; bract ca. 5 mm long, ovate-lanceolate, apex acute, base truncate, externally pubescent, glandular trichomes sparse; flowers ca. 2.5 cm long, pedicel ca. 0.5 cm long, hirsute, glandular trichomes apically sparse; bracteoles ca. 2.5 mm long, lanceolate, margins vinaceous, apex acute, base truncate, externally sericeous, trichomes on margin; calyx 7.6 mm long, sparsely sericeous externally, glabrous internally, dorsal lacinia rounded, fused on 4/5 of their length, ventral lacinia acute, fused on half of their length; vexillum oboval, apex retuse, base unguiculate, 9.9 × 7.6 mm, claw 2.8 mm long; wings obovate 9.2 × 3.6 mm, claw 2.9 mm long; keel petals obovate 8 × 3.3 mm, claw 2.9 mm long; stamens 6.4–7 mm long, anther 1.7 × 0.9 mm; gynoecium 8.6 mm long, ovary 2.5 mm long, ciliated, stipe 1 mm long, glabrous, style 5.1 mm long, stigma punctiform. Fruit with seminiferous region sparsely tuberculate on the margin, upper whorl 4.3–7.2 mm width, middle whorl 13–20 mm in width, lower whorl 6–8.2 mm in width.

Distribution and habitat:— Discolobium leptophyllum only occurs in the Central-West region of Brazil, in the State of Mato Grosso and north of Mato Grosso do Sul and Tocantins States. It is commonly reported in the Pantanal in floodable areas with high herbaceous vegetation; medium height herbaceous vegetation with evergreen trees; herbaceous tropical vegetation with palm trees; high herbaceous vegetation with trees covering less than ten per cent of the area, with or without shrubs; medium height herbaceous vegetation, practically without woody vegetation, dry or flooded most of the year and by water bodies. ( Figure 7 )

Phenology:—Flowers from January to May and fruits from February to May.

Distinguishing features:— Discolobium leptophyllum is distinguished from the other species by its leaves that can have up to 11 oblong-linear leaflets with entire reddish to blackened margins, terminal leaflets up to 14 cm long, two to three times longer than lateral ones, and bracteoles with vinaceous margins.

According to the original description, D. leptophyllum presents 1–3 foliolate leaves, and the type material has only one leaflet. When analyzing the specimens, we verified that 1-foliolate leaves are rare and that they occur at the branch base when present; the leaves of the specimens analyzed usually presented 5 to 11 leaflets. The aspect of the leaf found in the holotype results from the fall of lateral leaflets, a very common situation in both D. leptophyllum and D. junceum that probably led Burkart (1939) to synonymize both, which is not accepted in the present study.

Discolobium leptophyllum is easily differentiated by its leaflets with intramarginal venation and reddish to blackened margins and by its terminal leaflets that are always longer than 5 cm, while Discolobium junceum presents weak brochidodromous venation and leaflets that never exceed 1.2 cm long.

Specimens examined:— BRAZIL. Mato Grosso do Sul: Coxim, Fazenda Santa Rosa, Pantanal no leste do Paiaguás , 26 February 1987, A. Pott 2575 ( CPAP) ; Mato Grosso: Cuiabá, Rod. BR 364 próximo ao córrego Pindaival , 11 February 1975, W. R. Anderson 11336 ( HB, MBM, MO, NY) ; Luciara , 19 March 1997, V. C. Souza et al. 14595 ( CGMS, UFMT, UB, UEC) ; Luciara, Lake 2 km NW of Luciara, 08 October 1985, W. W. Thomas et al. 4298 ( NY), Poconé , 21 October 1991, M. Schessl 5256 ( UFMT) ; Poconé, Transpantaneira , 13 May 1981, C. J. da Silva 295 ( UFMT) ; Poconé, Transpantaneira, Estrada MT 060 Km 10, Pantanal , 27 February 1996, V. J. Pott et al. 2978 ( CPAP) ; São Félix do Araguaia , 11°27’S, 50°19’W, 25 November 1977, C. J. Falcão 5107 ( RB) ; São Félix do Araguaia, Estrada São Félix do Araguaia—Alto Boa Vista, Fazenda Agropasa , 15 March 1997, V. C. Souza et al. 14139 ( ESA) ; Rio Culuene , 16 January 1948, M. Victorino 22 (R) ; Rio Tuatuari , 12 May 1958, A. Lima 3145 ( RB) ; Vila Bela da Santíssima Trindade , 14°59’05”S, 59°55’06”W, M. F. Simon et al. 2342 ( CEN, RB, NY) ; Tocantins, estrada Alvorada— Peixe , 12°29’46,3”S, 49°00’50,7”W, 16 April 2006, C. P. Bone et al. 1639 ( RB) ; Tocantins, Palmas , 10°11’09”S, 48°24’00”W, 11 February 1999, G. F. Árbocz 6690 ( RB) .

4. Discolobium psoraleaefolium Benth. (1859: 72) . Lectotype (designated here):— BRAZIL, A. St-Hilaire 2561 (K000222461!, isolectotypes P00758427, P00758428 (photos!). Figure 4 .

Subshrub erect, 0.4–1.8 m tall, branch chestnut brown, subglabrous to sericeous, glandular trichomes sparse; leaf 6.5–13 cm long, petiole 2–5 cm long, subglabrous to adpressed-sericeous, glandular trichomes absent, ventrally canaliculate, rachis grooved, petiolule 1.4–2.5 mm long, velvety, stipules lateral, ca. 4 mm long, persistent, lanceolate to lanceolate-linear, apex acuminate, base truncate, glabrous to sericeous; 5–13 leaflets, oblong-linear or elliptical, apex rounded, mucronulate, base acute, opposed or sub-opposed, margin same color as blade; terminal leaflets slightly longer than lateral ones (ca. 0.5 cm) 15–40 × 2–7.5 mm, discolorous, adaxial surface glabrous, abaxial surface sparsely sericeous, glandular trichomes absent, main and secondary veins emerged on the abaxial surface, main vein densely pilose; inflorescence 30–50 cm long, stem sericeous, apex velvety, glandular trichomes absent; bracts 2–3.5 mm long, ovate-lanceolate to lanceolate-linear, margins green, apex acuminate, base truncate, externally sericeous; flowers 1.8– 2.2 cm long, pedicel 0.5–1 cm long, hirsute, glandular trichomes apically sparse; bracteoles ca. 3 mm long, lanceolate to lanceolate-linear, apex acute, base truncate, sericeous, glandular trichomes absent; calyx ca. 5.3 mm long, sparsely sericeous externally, glabrous internally, dorsal lacinia rounded, almost completely fused, ventral lacinia acute to slightly accuminate, fused on 3/5 of their length; vexillum suborbicular, apex obcordate, base unguiculate, 7.3 × 7.7 mm long, claw 1.3 mm long; wings obovate, 7.1 × 3.6 mm, claw 1.6 mm long; keel petals obovate, 5.8 × 3.1 mm long, claw 1.6 mm long; stamens 4.5–4.9 mm long, anther elliptic, 0.9 × 0.6 mm; gynoecium 5.8 mm long, ovary 1.6 mm long, ciliated, stipe 1.1 mm long, ciliated, style 3.1 mm long, stigma punctiform. Fruit with seminiferous region sparsely to densely tuberculate on margin; upper whorl 6–7.5 mm in width, middle whorl 15–20 mm in width, lower whorl 8–10 mm in width.

Distribution and habitat:— Discolobium psoraleaefolium is confirmed in Argentina, in the provinces of Corrientes, Formosa, and Misiones, and in Brazil, in the States of Mato Grosso and Rio Grande do Sul in floodable areas with high herbaceous vegetation with trees covering less than ten per cent of the area, with or without shrubs; medium height herbaceous vegetation, practically without woody vegetation, dry or flooded most of the year; medium height herbaceous vegetation with evergreen trees and on river or water body banks ( Figure 8 ).

Phenology:—Flowers from September to April and fruits from September to March.

Distinguishing features:— Discolobium psoraleaefolium is distinguished from the other species by its oblong-linear or elliptical leaflets and by the morphology of its calyx lacinia: dorsal ones are rounded, almost completely fused, while ventral ones vary from acute to slightly accuminate and are fused on 3/5 of their length. The leaflets of Discolobium psoraleaefolium resemble those of D. junceum , as for shape, but are always longer than 14 mm, while those of the latter species never exceed 12.5 mm long.

Discolobium psoraleaefolium and D. pulchellum can be confused by their leaflet number, but the former presents discolorous leaflets with well-marked secondary venation on the abaxial surface, whereas the latter has concolorous leaflets with non evident secondary venation.

Specimens examined:— ARGENTINA. Corrientes: Curuzú Cuatiá , 02 March 1945, T. S. Ibarrola 2541 ( LIL) ; Curuzú Cuatiá , 03 December 1941, M. Biraben 5167 ( LP) ; Curuzú Cuatiá, Rota Provincial 25, 09 October 2008, H. A. Keller et al. 6352 ( CTES) ; Mercedes, cruzamento Rota Provincial 23 sobre o Rio Miriñay , 04 November 1973, M. N. Correa et al. 5251 ( BAB) ; Mercedes , November 1936, A. P. Rodrigo 765 ( LP) ; Mercedes, Guayaibí, 22 Km sudeste de Mercedes, nascente do Arroio Guayaibí , 23 February 1984, S. G. Tressens et al. 2393 ( LIL, MBM) ; Mercedes, Estância Itá Caabó , 17 October 1961, T. M. Pedersen 6173 ( LP) ; Mercedes, Rio Miriñay e Rota 23, 17 November 1977, A. Schinini & C. Quarín 14451 ( CTES) ; Mercedes, Rota 123 Km 159, 10 December 1995, V. Solis Neffa et al. 220 ( CTES) ; Mercedes, Rota 23 e Rio Miriñay , 04 November 1973, A. Schinini 7753 ( LIL) ; Monte Caseros , 02 February 1945, T. S. Ibarrola 2290 ( LIL) ; Monte Caseros, Mocoretá , 03 March 1945, C. L. Schulz 200 ( LIL) ; Monte Caseros, Mocoretá , 16 February 1945, T. S. Ibarrola 2443 ( LIL) ; Monte Caseros, Rio Mocoretá e Rota 14, 25 February 1984, S. G. Tressens et al. 2505 ( CTES) ; Paso de Los Libres, Cabred , 25 January 1945, T. S. Ibarrola 2180 ( LIL) ; San Martín, sobre Rio Uruguay , 08 February 1979, A. Schinini et al. 16838 ( CTES,K) ; San Martín, Rota 40, 6 Km norte de acesso a Yapeyú , 28 January 1976, A. Krapovickas & C. L. Cristóbal 29003 ( LIL) ; San Martín, Yapeyú , 18 December 1946, A. M. R. Huidobro 3743 ( LIL) ; Santo Tomé , 07 October 1971, R. Carnevali 2693 ( LIL) ; Santo Tomé, Estabelecimento Las Marías, Rota Nacional 14, 7 Km sul de Gobernador Virasoro, 01 December 1970, A. Krapovickas et al. 16822 ( BAB, IAC, LP, MBM, P) ; Santo Tomé, Estancia Garruchos, cachoeira, Arroio Chimiray , 06 February 1972, A. Krapovickas et al. 21199 ( LIL, LP) ; Santo Tomé, Gobernador Virasoro, 10 Km oeste por Garruchos , 08 November 1998, G. Seijo 1266 ( CTES) ; Santo Tomé, Subi Grande , 08 December 1944, T. Ibarrola 1611 ( LIL) ; Formosa: s/l, Rota 11, 30 Km sul de Formosa, 19 April 1987, C. L. Cristóbal & A. Krapovickas 2167 ( IAC, LIL) ; Pilagás, Espinillo , 24 September 1970, A. G. Schulz 17572 ( CTES) ; Misiones: Apostoles, Rio Chimiray , 09 November 1944, T. Ybarrola 1145 ( LIL) ; Capital, Garupá, Camping Municipal , 16 September 1981, P. Legname et al. 8572 ( LIL) ; Capital, nas margens do Arroio Garupá , 22 November 1980, P. Legname et al. 7661 ( LIL) ; Capital , 30 September 1978, P. Legname et al. 5518 ( LIL) ; Pindapoy , 08 December 1941, M. Biraben 5398 ( LP) .— BRAZIL. Mato Grosso: Novo Santo Antônio , 12°22’29,9”S, 50°55’15,3”W, H. Jancoski 109 ( RB) ; Rio Grande do Sul: s/l, Região da Campanha , December 1985, J. F. M. Valls 9666 ( ICN, IPA) ; s/l, Região da Campanha , December 1985, J. F. M. Valls 9691 ( ICN) ; Itaqui, Rod. BR 472 Km 507, 13 January 2002, S. T. S. Miotto 2022 ( FLOR, ICN) ; Itaqui, Rod. BR 472 Km 507, 13 January 2002, E. Biondo 225 ( ICN) ; São Vicente do Sul, Cerro Loreto e proximidades, 06 December 1986, G. L. Webser 25968 ( ICN) ; São Vicente do Sul, Cerro Loreto , December 1986, M. Sobral et al. 5359 ( ICN) ; Uruguaiana, Saladero, Barra do Quaraí , 20 March 1993, S. Miotto 1402 ( ICN) ; Uruguaiana , 24.I.1948, Palacios-Cuezzo 243 ( LIL) ; Uruguaiana, Arroio Imbaá , November 1984, M. Sobral 3330 ( EAC, ICN, INPA, RB, SP) .

Figures

FIGURE 2. Discolobium junceum Micheli. A. Branch with inflorescence. B. Leaflet. C. Bract. D. Bracteole. E. Calyx. F. Vexillum. G–H. Wing. I–J. Keel petals. K. Androecium. L. Gynoecium. M. Fruit. (A–L from T. Rojas 12521 (LIL), M from R. H. Fortunato 2110 (INTA))

FIGURE 3. Discolobium leptophyllum Benth. A. Branch with inflorescence, buds and fruits. B. Leaflet. C. Bract. D. Bracteole. E. Calyx. F. Vexillum. G–H. Wing. I–J. Keel petals. K. Androecium. L. Gynoecium. M. Fruit. (A–M from V. J. Pott 2978 (CPAP))

FIGURE 4. Discolobium psoraleaefolium 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. (A–L from E. Biondo 225 (ICN); M from P. Legname 7761 (LIL))

FIGURE 7. Geographical distribution of species of Discolobium in South America: ▲ Discolobium hirtum, ■ Discolobium junceum, ● Discolobium leptophyllum.

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