Arquita E. Gagnon, G. P. Lewis & C. E. Hughes, Taxon 64(3): 479. 2015

Gagnon, Edeline, Bruneau, Anne, Hughes, Colin E., de Queiroz, Luciano Paganucci & Lewis, Gwilym P., 2016, A new generic system for the pantropical Caesalpinia group (Leguminosae), PhytoKeys 71, pp. 1-160 : 69-71

24. Arquita E. Gagnon, G. P. Lewis & C. E. Hughes, Taxon 64(3): 479. 2015 Figs 38 , 39I-O

Type.

Arquita mimosifolia (Griseb.) E. Gagnon, G. P. Lewis & C. E. Hughes.

Description.

Small to medium-sized, often decumbent shrubs, 0.3-2.5 m in height, slender in stature, usually with glandular trichomes on various parts of the plant; young stems and inflorescence rachises red-orange to maroon. Stipules ovate-obovate to deltoid, chartaceous, 2.5-5.5 mm long, usually with a fimbriate-glandular margin and short-stalked glands (except in some specimens of Arquita ancashiana ), caducous. Leaves bipinnate, with 1-5 pairs of pinnae, usually with a single terminal pinna; petiole (0.3-) 0.5-6 cm long; rachis 0.5-6 cm long (but sometimes absent); leaflets in 4-12 opposite pairs per pinna, oblong-obovate, 2.5-10 (- 14) × 1-3.5 (- 6) mm, often with maroon/black glands in depressions on crenulated leaflet margins, and sometimes with occasional sessile black glands on the undersurface of leaflet blades (in Arquita ancashiana the glands are submarginal on the lower half of the basal leaflets of the pinnae). Inflorescences leaf-opposed, determinate racemes (with only 1 to 2 flowers open at a given time), (5-) 7-21 (- 41.5) cm long; bracts lanceolate, acuminate, either eglandular or covered in gland-tipped trichomes, 2.75-7 mm long, caducous. Flowers bisexual, zygomorphic; calyx comprising a hypanthium, and 5 sepals, 6-11 mm long, caducous, the lower sepal cucullate, and sepals either have an entire or glandular-fimbriate margin; petals 5, free, yellow to orange, median petal, sometimes streaked red, 6-17 × 4-12 mm, claw pubescent at the base, either flat or inrolled, sometimes with stipitate-glandular trichomes on the dorsal surface of the whole petal, upper and lower lateral petals 6-17 × 3-12 mm; stamens 10, free, 5-13 mm long, anthers 0.75-2.3 mm long, the stamens deflexed and loosely grouped around the gynoecium; ovary usually covered with gland-tipped trichomes. Fruits laterally compressed, lunate-falcate pods with a marcescent style, covered sparsely to densely with gland-tipped trichomes, these sometimes dendritic, 2-4.7 × (0.7-) 0.9-1 cm. Seeds laterally compressed, ovate-orbicular, 4.5-6 × 3.5-4.5 × 1 mm, the testa shiny olive-grey, sometimes mottled or streaked black.

Geographic distribution.

The genus Arquita comprises six taxa in five species restricted to the Andes in South America, in disjunct inter-Andean valleys, in Ecuador, Peru, Bolivia and Argentina.

Habitat.

Seasonally dry, montane, rupestral habitats in inter-Andean valleys.

Etymology.

The name Arquita derives from the vernacular name of Arquita trichocarpa in Argentina ( Ulibarri 1996).

Notes.

A revision of Arquita with a complete key to species is available in Gagnon et al. (Taxon 64(3): 468-490, 2015).

References.

Burkart (1936); Ulibarri (1996); Lewis (1998: 167-171, 174-179); Lewis et al. (2010); Gagnon et al. (2015: 468-490).

Figures

Figure 38. Arquita mimosifolia (Griseb.) E. Gagnon, G. P. Lewis & C. E. Hughes. A flowering branchlet B stipule C eglandular leaflet undersurface D glandular leaflet undersurface E detail of glands on stem F inflorescence G bract H calyx opened out I median petal J lateral petal K stamen L gynoecium M stigma N detail of glands on ovary O fruits. A-E, G-N from Kiesling et al. 4990 F from Lorentz s. n. O from Schreiter 68526. Drawn by Eleanor Catherine.

Figure 39. Pomaria pilosa (Vogel) B. B. Simpson & G. P. Lewis. A inflorescences (A. A. Schneider, Flora Digital (http: // www. ufrgs. br / fitoecologia / florars /), Rio Grande do Sul, Brazil, unvouchered). Pomaria rubicunda (Vogel) B. B. Simpson & G. P. Lewis B flowers C inflorescences (S. Bordignon, Flora Digital (http: // www. ufrgs. br / fitoecologia / florars /), Rio Grande do Sul, Brazil, unvouchered). Pomaria jamesii (Torr. & Gray) Walp. D flower E fruit (P. Alexander, SEINet Arizona Chapter (http: // swbiodiversity. org / seinet / imagelib /), Arizona, USA, unvouchered); Pomaria burchellii (DC.) B. B. Simpson & G. P. Lewis subsp. burchellii (captions continued on next page) F flower G habit H fruits (O. Bourquin, Flora of Zimbabwe (http: // www. zimbabweflora. co. zw /), Ghanzi district, Botswana, unvouchered). Arquita grandiflora E. Gagnon, G. P. Lewis & C. E. Hughes I flower and buds (C. E. Hughes, Ancash, Peru, Saerkinen et al. 2225 (FHO )). Arquita celendiniana (G. P. Lewis & C. E. Hughes) E. Gagnon, G. P. Lewis & C. E. Hughes J flower (E. Gagnon, Cajamarca, Peru, Hughes & al. 3097 (MT )). Arquita trichocarpa (Griseb.) E. Gagnon, G. P. Lewis & C. E. Hughes K inflorescence M fruit (E. Gagnon, Salta, Argentina, Gagnon & Atchison 218 (MT )) O habit (E. Gagnon, Jujuy, Argentina, Gagnon et al. 204 (MT )). Arquita ancashiana (Ulibarri) E. Gagnon, G. P. Lewis & C. E. Hughes L undersurface of leaflet (E. Gagnon, Cajamarca, Peru, Hughes et al. 3065 (MT )). Arquita mimosifolia (Griseb.) E. Gagnon, G. P. Lewis & C. E. Hughes N fruit (E. Gagnon, Salta, Argentina, Gagnon et al. 203 (MT )).