Ricoa Duno & Torke, 2022

Tamayo-Cen, Ivan, Torke, Benjamin M., Lopez Contreras, Jose Enrique, Carnevali Fernandez-Concha, German, Ramirez Morillo, Ivon, Can Itza, Lilia Lorena & Duno de Stefano, Rodrigo, 2022, Revisiting the phylogeny and taxonomy of the Pithecellobium clade (Leguminosae, Caesalpinioideae) with new generic circumscriptions, PhytoKeys 205, pp. 279-298 : 279

Ricoa Duno & Torke gen. nov.

Type.

Ricoa leptophylla (DC.) Duno & Torke.

Diagnosis.

Similar to Painteria in shrubby habit with pronounced growth dimorphism into long- and short-shoots, deciduous microphyllous leaves and recurved pods with the fruit valves coriaceous to lignescent and elastically reflexed with age, but differing in the leaves with 3-7(9) pairs of pinnae (vs. 1-2 in Painteria ), the leaflets 10-25 per pinna (vs. 3-12), the floral bracts 0.8-2.1 mm long (vs. 0.4-0.7 mm), the flowers shortly pedicellate (vs. sessile) and the corolla lobes recurved (vs. erect-ascending).

Description.

Low xerophytic stiffly branched microphyllous shrubs 2-1.5 m tall, often growing in patches several metres in diameter, armed at each node of flexuous long shots with a pair of lignescent stipules, young growth indumented with minute whitish hairs. Stipules converted with straight to recurved spines with a thickened base, the spines 3-10 mm long. Leaves bipinnate with 3-7 (9) pairs of pinnae; leaflets 8-25 pairs per pinna, the primary leaf axis 0.5-5 cm long, with the petiole 2.5-10 (18) mm long and a subsessile circular nectary between the first pinnae pair (sometimes also between the second pair), nectaries absent on pinna-rachises; leaflets opposite, narrowly- or linear-oblong or lanceolate, semi-cordate at base, obtuse to weakly apiculate at apex, puberulous abaxially, marginally ciliate, the venation weakly developed, nearly simple or 1-branched, the mid-rib prominulous only dorsally, subcentric. Inflorescence of capitula arising from brachyblasts, peduncle 1-18 mm long; receptable clavate, 1.5-2.5 mm long, capitula globose, 1-1.5 cm in diameter, 16-35-flowered; bracts linear-oblanceolate or spatulate, 0.8-2.1 mm long, persistent into anthesis. Flowers externally homomorphic, but some functionally staminate, pedicellate, perianth 5-merous; pedicel 0.2-0.6 mm long; calyx campanulate, contracted at base, 1.3-3.2 mm long, minutely puberulent (or just on teeth), teeth ovate or deltate, 0.2-0.9 mm long; corolla reddish or greenish, tubular, 3.5-5 mm long, lobes ovate, recurving. 1.2-1.9 mm long, puberulous and densely fimbriolate on lobes; androecium 40-76-merous, 5-10.5 mm long, tube 2-4 mm long; ovary slenderly ellipsoid, compressed, glabrous, on a short stipe 1-1.4 mm long, style in bisexual flowers often longer and more robust than stamens. Pods l-2 (4) per capitulum, falcately or subcircinnately broadly linear in profile, attenuate into an erect cusp 2-6 mm long, the body 7-11.5 × 1.1-1.9 cm, 8-10-seeded, the valves stiffly leathery, at first plano-compressed, becoming turgid and low-convex (on both faces of pod) over each seed, densely grey puberulent, becoming glabrescent and dark castaneous, indistinctly venulose, the cavity continuous, dehiscence inert through both sutures; funicle straight or sinuous (but not sigmoid), seeds obliquely descending, 8-10, plumply lentiform, 7.5-11 × 3-4 mm, the testa smooth, hard, moderately lustrous, dark castaneous, the pleurogram incomplete.

Distribution.

Ricoa is found scattered over the Mexican Central Plane, in the States of Chihuahua, Coahuila, Durango, Guanajuato, Hidalgo, Jalisco, México, Michoacán, Oaxaca, Puebla, Querétaro, San Luis Potosí, Tlaxcala and Zacatecas.

Habitat.

It grows in grasslands, scrubs and at the lower edge of the pine-oak belt, on both basaltic and calcareous substrates, at 1600-2800 m elev. Plants flower between March and August.

Common names.

The common name is Huisache. This name is also given to Vachellia farnesiana (L.) Wight & Arn. and other related species ( Barneby and Grimes 1996). Other common names are charrasquillo, gatuña and tehuixtle ( Calderón de Rzedowski 2007).

Etymology.

The generic name honours María Lourdes Rico, whose profound dedication and perseverant commitment to botanical research over decades has deeply enhanced knowledge and understanding of the Leguminosae, especially tribe Ingeae .