Amburana acreana (Ducke) A. C. Smith (1940: 62)

Seleme, Elidiene P., Lewis, Gwilym P., Stirton, Charles H., Sartori, Ângela L. B. & Mansano, Vidal F., 2015, A Taxonomic Review And A New Species Of The South American Woody Genus Amburana (Leguminosae, Papilionoideae), Phytotaxa 212 (4), pp. 249-263 : 251-252

1. Amburana acreana (Ducke) A. C. Smith (1940: 62)

Basionym: Torresia acreana Ducke (1935: 205) . Type:— BRAZIL. Acre: Seringal Iracema, Rio Acre, em ilha não inundável, May 1933, A. Ducke 23769 (lectotype, designated here, RB547648!, isolectotypes K000500808! NY00033875! P03207065!) ( Figs. 1 & 2 ).

Tree to ca. 30 m tall. Stems smooth, rust colored. Leaves 15–35 cm long; petiole 14–17 mm long, pilose; leaflets 17–25 per leaf, 8–6 × 2–3 cm, alternate, ovate-lanceolate, apex acuminate, base rounded, midrib raised on the abaxial surface. Inflorescence lax, axillary or terminal, 4–10 cm long; peduncle 1.5–3 cm long, bracteoles ovate, pilose; flowers 10–18 mm long; standard petal white, 10–15 mm long, pilose adaxially; calyx campanulate, glabrescent, teeth shallow; stamens 10, filaments curved upwards, 5 vexillary, ca. 1 mm long, 5 abaxial, ca. 6 mm long; ovary ca. 4 mm long, glabrous. Fruit linear-oblong, 5–7 × 0.6–1 cm, a membranous endocarp surrounding the seed and forming a papery wing; seeds 1 (2) in the distal portion of the fruit, ellipsoid, 12–14 × 7–9 × 2–3 mm, black.

Distribution and habitat:— Amburana acreana occurs in the Amazonian Basin of northern Brazil (Acre and Rondonia states), Bolivia and Peru, on or near river banks, in rain forest, usually terra firme forest, but it may occur in periodically flooded areas ( Fig. 7 ).

Phenology:—Flowering March to October, fruiting April to October.

Taxonomy:— Amburana acreana can be distinguished from the other two species by its rust colored, darker stems (versus brown in A. cearensis and A. erythrosperma ); the number of leaflets per leaf (17–25 versus 7–15 in A. cearensis and 7–13 in A. erythrosperma ); leaflet shape (ovate-lanceolate versus elliptic to ovate in A. cearensis and A. erythrosperma ), leaflet apex (acuminate versus obtuse to retuse in A. cearensis and A. erythrosperma ); and the larger, 4–10 cm long and laxly branched inflorescence (versus 2–5 cm long and congested in A. cearensis and A. erythrosperma ).

In the description of the species, both fruiting and sterile material was used. The material deposited in RB is designated here as lectotype, because it is complete and morphologically representative material collected by Ducke.

Specimens examined: — BOLIVIA. La Paz: S. Yungas, Base do Rio Bopi , 690–750 m, 27–31 July 1939, B. A. Krukoff s.n. ( K) . BRAZIL. Acre: Mâncio Lima, Alto Rio Moa , parque Nacional da Serra do Divisor , comunidade do Igarapé Bruquinez , 217 m, 7°27’19”S, 73°38’80”W, 14 November 2007, H. C. de Lima et al. 6727 ( RB). Espírito Santo, Linhares, Rodovia BR 101 km 139, CULTIVADA área particular, 20 June 2011, E. P. Seleme et al. 462 ( RB). Rio de Janeiro: Rio de Janeiro, Jardim Botânico do Rio de Janeiro, CULTIVADA Canteiro 14- A, 05 May 2005, L. F. G. da Silva et al. 59 ( RB) ; Rio de Janeiro, Jardim Botânico do Rio de Janeiro, CULTIVADA Canteiro 14- A, 16 June 1989, V. F. Gonçalves s.n. ( RB) ; Rio de Janeiro, Jardim Botânico do Rio de Janeiro, CULTIVADA Canteiro 14- A, 25 April 1986, H. C. de Lima et al. 2682 ( RB, HUEFS) ; Rio de Janeiro, Jardim Botânico do Rio de Janeiro, CULTIVADA Canteiro 14- A, 10 October 1984, H. C. de Lima 2164 ( RB) ; Rio de Janeiro, Jardim Botânico do Rio de Janeiro, CULTIVADA Canteiro 14- A, 26 October 1983, H. C. de Lima 2073 ( RB). Rondônia: Alvorada do Oeste , Linha 64, a 04 km da BR 429 em direção a Costa Marques , 11°25’S, 62°30’W, 01 May 1987, C. A. C. Ferreira 8980 ( K) ; Costa Marques , cerca de 5 km NW de Costa Marques, 150 m, 12°25’S, 64°14’W, 29 March 1987, M Nee 34551 ( K) ; Eixo JP 14 , 9°15’S, 61°50’W, 21 October 1987, S. Romaniuc Neto et al. 687 ( HUEFS, MBM, SP, SPF) . PERU. Echarate: San Antonio, 1036 m, 12°38’56”S, 72°55’25”W, 23 March 2006, L. Valenzuela et al. 6698 ( K, MO) ; San Antonio, Rio Sapapoari, 1030 m, 12°38’56”S, 72°55’25”W, 23 March 2006, J. Farfán et al. 968 ( K, MO) ; San Antonio, Cirialo, 1320 m, 12°39’59”S, 72°54’39”W, 25 March 2006, I. Huamantupa et al. 7387 ( K, MO) ; San Antonio, Cirialo , 1320 m, 12°39’59”S, 72°54’39”W, 24 March 2006, I. Huamantupa et al. 7379 ( K, MO) - Leoncio Prado: Huanuco, Província Panao, distrito Pachitea, 26 July 1962, R. L. Magin 22 ( K) ; Huanuco, Província Pachitea, distrito Honoria , 220 m, 04 April 1964, R. L. Magin 126 ( K) ; Manu: Manu, Parque Nacional Manu , Rio Manu , Pakitsa Estação , Tachigali Trail para 8 km N do campo, 350 m, 11°56’S, 71°16’W, 25 December 1988, R. B. Foster & S. Baldeon 12804 ( K, US) ; San Martin: Chazuta, Rio Huallaga , 260 m, April 1935, G. Klug 4064 ( K) ; Tarapoto , December 1856, R. Spruce 4959 ( K) ; Ucayali: Pucallpa, Pucallpa para Tingo Maria km 85, reserva Von Humboldt , 250 m, 8°48’12”S, 75°03’79”W, 5 August 2001, T. D. Pennington & A. Daza 17174 ( K); Pucallpa para Tingo Maria km 85, reserva Von Humboldt, 250–350 m, 8°48’12”S, 75°03’79”W, 24 September 2000, T. D. Pennington et al. 16994 ( K) .

Figures

FIGURE 2. Amburana acreana. A. Branch with leaves; B. Inflorescence; C. Leaflet (adaxial face); D. Detail of midvein in C; E–F. Bracteole (abaxial and adaxial face, respectively); G. Flower bud; H. Flower in side view; J. Flower (with the petal removed) in side view showing the stamens and carpel; K. Standard (adaxial face); L. Longitudinal section of flower showing hypanthium and stamen insertion; M. Fruits; N. Winged seed (A from L. F. G. da Silva et al. 59, B–L from S. Romaniuc Neto et al. 687, M–N from T. D. Pennington et al. 16994). Drawn by Ana L. Souza.

FIGURE 7. Geographical distribution of Amburana acreana (■), A. cearensis (●) and A. erythrosperma (▲). Map created using Diva GIS.