Name

Acaciella sousae (L. Rico) L. Rico, Kew Bull. 59:  328. 2004.

Rico Arce & Bachman
Anales del Jardín Botánico de Madrid
Vol. 63(2): 189-244
July-December 2006

Synonymy and types

Acacia sousae L. Rico, Brittonia 39: 130. 1987. Type: Mexico: Guerrero, Distrito de Mina, Puerto de  la Calavera, G.B. Hinton 9541 (holotype, US!;  isotypes, GH!, K!, NY!, P!, TEX!).

Formal description

Shrub to 1.6 m tall; twigs glabrous, glaucous. Stipules  lanceolate, up to 5 mm long, fugacious. Leaves 9-  18 cm long, petiole (2.5)3.8-5.5 cm long, terete,  glabrous; rachis 2.8-3.4 cm long, glabrous, with 1-3  pairs of pinnae; pinnae 5-12 cm long; paraphyllidia  1.5 mm long; leaflets 1-3 pairs per pinna, (1.8)3-4.5 ×  (1.2)2-3.5 cm, broadly obovate, base oblique, apex  rounded, venation brochidodromous, main vein subcentral  at the base, central towards the apex, secondary  venation conspicuously pinnate-reticulate,  glabrous, chartaceous. Inflorescences consisting of  solitary, axillary capitulum-like racemes, or in clusters  of up to 5 capitulum-like racemes, main axis to 23 cm  long, glabrous; peduncles 1.5 cm long; glabrous; inflorescence  bracts not seen; floral bract 0.75 mm long,  glabrous, clavate, fugacious; pedicels 1.5-2 mm long,  glabrous; flowers white, yellow when dry, these up to  6 mm in diam. at anthesis. Calyx 1 mm long, 5-lobed,  the lobes less than ¼, the length of the whole calyx,  glabrous. Corolla 2.4 mm long, 5-lobed, the lobes to  more than half the whole corolla length, glabrous. Stamens  7-8 mm long. Ovary 1 mm long, glabrous, shortstipitate,  the stipe shorter than the ovary; basal nectary  0.7 mm high. Legume 4.5-5.5 × 1.3-1.8 × 0.3 cm,  flat, straight, late dehiscent; valves chartaceous, conspicuously  reticulate, glabrous, rounded at the base  and apex; stipe 1.5-2 cm long; beak present, 4 mm  long, very often breaking off. Seeds 4-7 per fruit, 4.3-  4.5 × 3.3-3.5 × 0.6 mm.

Distribution

Mexico central and southwestern: a  species of restricted distribution, found only in the Rio  Balsas Basin: Guerrero, Puebla and Morelos.

Additional info

Habitat. Low deciduous forest and transitional vegetation  to xerophytic scrub (matorral), grassland;  prefers limestone soils. Alt. 500-1500 m.

Flowering time

Flowering in March, and September to  October, fruiting from August to October. 

Representative specimens

MEXICO:

Guerrero:

• 3 km W of Apanguito, Atenango del Río,  18º 05' N, 99º 06' W, 808 m, 5-X-1981, Campos, G. 232 (FCME);
• Los Limones, km 62 road Cuernavaca-Iguala, 18º 04' N, 101º 35'  W, 1200 m, 14-X-1987, Contreras, J.L. 2155 (FCME);
• 3 km NW of  San Francisco Ozomatlan, 17º 54' N, 99º 17' W, 1230 m, 19-IX-  1989, Vargas-Pérez, A. 100 (FCME).

Puebla:

• 10 km adelante de  Matamoros, 18º 36' N, 98º 28' W, 1500 m, 16-X-1984, Dorado,O.  1199 (MEXU);
• Izúcar de Matamoros, 10 km adelante, rumbo a  Tehuitzingo, 18º 21' N, 98º 17' W, 1500 m, 16-VIII-1984, Dorado, O. 1359 (BM, K, MEXU).

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