Mucuna argentea T.M. Moura, G.P. Lewis & A.M.G. Azevedo, Kew Bull.

De, Tânia M., Lewis, Gwilym P., Mansano, Vidal F. & Tozzi, Ana M. G. A., 2018, A revision of the neotropical Mucuna species (Leguminosae-Papilionoideae), Phytotaxa 337 (1), pp. 448-450 : 448-450

2. Mucuna argentea T.M. Moura, G.P. Lewis & A.M.G. Azevedo, Kew Bull. 68 (1): 143–150. 2013. ( Fig. 2 )

TYPE:— COLOMBIA, Araracuara , 18 August 1994 (fl./fr.), B. Katys & A. van Dulmen AVD 265 (holotype: K!; isotypes: COAH!, MO!) .

Liana. Leaves 3-foliolate; pulvinus 15 × 3.0–5.0 mm; petiole 12–13 cm long; stipels persistent; rachis 1.5–3.0 cm long; petiolules 5.0–8.0 mm long; lateral leaflets, 12–18 × 8.0– 11.5 cm, asymmetric at base, cuspidate at apex; apical leaflets obovate or elliptic, 13–17 × 9.0– 12 cm, acute to rounded at base, cuspidate at apex; venation eucamptodromous, secondary veins in 7.0–9.0 pairs per leaflet; dense, adpressed silvery hairs on abaxial surface; less dense adaxially. Inflorescence axillary, umbel-like pseudoraceme (in which all flowers are closely clustered at the inflorescence apex and where the floral internodes are so reduced as not to be evident); peduncle 7.0– 10 cm long; bracts ca. 3.0 cm long, caducous; pedicels 1.5–2.0 cm long. Flowers 8.0–9.0 cm long; calyx reported to be greenish yellow (R. López et al. 4009 COAH), 2.0– 2.5 cm long, 4-lobed, the adaxial lobe formed by two connate sepals, 5.0 × 3.0 mm, obtuse at apex, the other three lobes 5.0–7.0 × 3.0 mm, acute at apex; corolla reported to be yellow (J.G.R. Arango et al. 8243 COAH); standard broadly elliptic, 5.0–6.0 × 3.0 cm, attenuate at base, rounded to retuse at apex, claw 5.0–6.0 mm long; wings oblong-ovate, 7.0–9.0 × 1.0– 1.5 cm, attenuate at base, acute at apex, the claw 7.0–9.0 mm long; keel petals oblong, 7.0–8.5 × 2.0 cm, attenuate at base, acute at apex, the claw 7.0–9.0 mm long; pubescent at base of wing and keel petals. Stamen filaments reported to be cream coloured (R. Callejas & O. Marulanda 7092 COAH, MO), 8.0– 10 cm long, glabrous. Gynoecium 10 cm long; style 8.0–9.0 cm long, sericeous, except at apex; ovary 10 × 4.0 mm, sericeous; stigma peltate, villous. Fruits 20 × 3.5 cm, acute at base, cuspidate at apex, not ornamented by lamellae, covered with dense hairs. Seeds not seen.

Taxonomic notes:— Mucuna argentea Moura et al. (2013b: 143–144) differs from the other species with an umbel-like pseudoracemose inflorescence [ M. cajamarca (in Moura et al. 2013b: 144), M. cuatrecasasii , M. elliptica ( Ruiz & Pavon 1798: 176) De Candolle (1825: 405) , M. klitgaardiae (in Moura et al. 2013b: 149), and M. pseudoelliptica (in Moura et al. 2014a: 891)] by its silver coloured hairs on the abaxial surface of the leaflets, a characteristic that does not occur on the other species. Mucuna argyrophylla Standley (1922: 509) also has silvery hairs on the abaxial surface of its leaflets, but its inflorescence is pseudoracemose (not umbel-like) with the rachis 3.0–5.0 cm long and the internodes 2.0–3.0 mm long and clearly evident, a suite of characters which distinguish it from M. argentea .

Phenology:— Flowering June to January, with most flowering specimens in herbaria collected in August; fruiting August to November.

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Distribution and habitat:— Mucuna argentea occurs in Colombia, Ecuador and Peru ( Fig. 3 ). Field labels report the species to grow in ‘selva’ (R. Jaramillo et al. 406 US), disturbed forest (J.G.R. Arango et al. 8243 COAH) and secondary forest (R.N. Mowbray 6991 MO, NY), frequently close to rivers (B. Kats & A. van Dulmen AVD 265 COAH, K, MO; J. Brandbyge et al. 33631 AAU, MO). In general it occurs at low elevations, (160–450 m), but it also has been reported at 1300 m in Meta, Colombia.

Conservation status:— Mucuna argentea is preliminarily ranked as being of Least Concern (LC) [EOO 366,123.36 km 2; AOO 60km 2]. Although Moura et al. (2013b) considered this species to be Endangered, more recently seen collections have confirmed that the species occurs within protected areas and is therefore under less threat than previously assumed. No decline or fluctuation in known populations has been recorded.

Vernacular name:—‘ Calates huasca’ in Sucumbios, Ecuador ( W. Sarabia & P. Gamboa 911 Q) .

Representative specimens examined:— COLOMBIA. Caquetá: Caquetá Peña Roja, cerca al Centro Experimental Araracuara, Amazonas , orilla del rio Caquetá, 18 August 1994 (fl./fr.), B. Kats & A. van Dulmen AVD 265 (holotype K; isotypes COAH, MO) . Cauca: Guayuyacu , 23 July 1984 (fl.), J. Laferriere 205 ( MO) . Meta: La Macarena, vereda ‘ Yarumales arriba’, finca bordando ciénaga de Río Guayabero , 12 August 1988 (fl.), R. Callejas & O. Marulanda 7092 ( COAH, MO) ; Mpio. de La Macarena, Vereda “Marimbas 1”, valle aluvial de origen Amazónico , 8 July 2004 (fl.), J.G.R. Arango et al. 8243 ( COAH) . Putumayo: selva higrofila del Rio Putumayo, 24 November 1940 (fl./fr.), J. Cuatrecasas 10797 ( US); Cordillera la Macarena, mesa del rio Sansa , 23 January 1951 (fl.), J.M. Idrobo & R.E. Schultes 1279 ( US); Acacías , en selva, 1 January 1946 (fl.), R. Jaramillo et al. 406 ( US); Lejanías , vereda el triunfo, 20 July 1998 (fl.), R. Lopéz et al. 4009 ( COAH) ; zona de preservacion del AMEN, 1 August 2000 (fl./fr.), R. Lopéz et al. 6736 ( COAH) . Vaupés: Taraira , 22 November 1994 (fl.), D. Cárdenas et al. 6116 ( COAH, K, MO) . ECUADOR. Napo: Puerto el Carmen de Putumayo , August 1980 (fl.), R. Andrade 33014 ( AAU) ; Rio Cuyabeno , 17 August 1981 (fl./fr.), J. Brandbyge et al. 33631 ( AAU, MO) ; 17 July 1978 (fl.), M. T. Madison et al. 5401 ( AAU) ; Napo road, Limoncocha , September 1969 (fl.), R.N. Mowbray 6991 ( MO, NY) . Sucumbios: Cantón Shushufindi, parroquia Limoncocha, sector Pishira , June 2002 (fl.), W. Sarabia & P. Gamboa 911 (Q) . PERU. Loreto: Rio Putumayo, May-July 1931 (fl.), G. Klug 2265 (K, MO) .

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Figures

FIGURE 2. Mucuna argentea. A—Leaf and inflorescence. B—Indumentum on abaxial surface of leaflet. C—Calyx opened out. D—Standard petal. E—Wing petal. F—Keel petals. G—Androecium (9 + 1) and apex of gynoecium. H—Ovary. J—Immature fruit. Figure first published in Moura et al. (2013b). Drawn by Margaret Tebbs.

FIGURE 3. Geographical distribution of the six species of Mucuna with umbel-like pseudoracemose inflorescences endemic to South American.