Cenostigma pluviosum var. maranionum (G.P.Lewis & C.E.Hughes) Gagnon & G.P.Lewis

Lewis, G.P., Hughes, C.E., Yomona, A.D. et al. 2010. Three new legumes endemic to the Marañón Valley, Perú. Kew Bulletin 65: 209. DOI: https://doi.org/10.1007/s12225-010-9203-6

Type

Perú, Cajamarca, Celendín, Marañón Valley, km 50 rd from Celendín to Leimebamba, 23 April 2002, fl. & fr., Hughes 2215, Daza & Forrest (holotypusFHO!; isotypi K!, MOL!).

Morphology General Habit

Shrub or small, often multi-stemmed, much branched tree, 1.8 – 5 m tall, with a dense rounded crown, trunk or main stems 4 cm in diam., bark silvery mid grey-brown, characteristically exfoliating in delicate papery vertical strips, the bark somewhat rougher on older stems, slash pale brown, inner bark green; young branches glabrous, or finely puberulous to sparsely pubescent, glabrescent, or the outer papery bark with scattered stellate white trichomes, or reddish orange glandular trichomes surrounded by simple hairs, the stems, leaf rachises and petioles with scattered pustular glands

Morphology Leaves Stipules

Stipules spatulate, 8 – 10 × 4 – 5 mm, the outer surface sparsely puberulous, and with a scattering of dark sunken glands, the tapering base with short-stalked glands, the margin fimbriate, glandular and ciliate, caducous

Morphology Leaves

Leaves bipinnate, pinnae in 2 – 4 pairs per leaf, plus a single terminal pinna, the basal 1 – 2 pairs alternate to subopposite, the apical pair opposite (and together with the single terminal pinna digitate); petiole 2 – 4 cm long, the basal pulvinus plump and somewhat expanded, a brown axillary perulate resting bud in the petiole axil; leaf rachis 2.5 – 8 cm long; leaflets alternate to subopposite, subsessile (the leaflet blade±auriculate around the upper \( \frac{2}{3} \) of the pulvinule), sub-coriaceous, 7 – 11 per pinna (each pinna with either a single terminal leaflet or a pair of leaflets), the pulvinule drying black in contrast to the yellowish midvein; distal leaflets of the terminal pinnae ovate, obovate or widely elliptic, 1.7 – 3 × 1.1 – 1.9 cm, the apex rounded to shallowly retuse, the base asymmetric, the midvein sometimes falcate, the median leaflets of the lower pinnae varying in shape from sub-circular to sub-quadrangular to ± rectangular, elliptic-rhombic or trapezoid, 1.4 – 2.2 (– 2.8) × 1 – 1.5 (–1.8) cm, apex rounded to shallowly retuse, base obtuse to inequilaterally truncate, upper surface of all leaflets sparsely to moderately puberulous to pubescent, or glabrous, sometimes only the midvein hairy, or only the pulvinule and the base of the midvein hairy (in material from Bagua Chica), occasionally shiny, the lower surface sparsely to moderately pubescent, or glabrous, dull, the margin ciliate (on material from Bagua Chica), the midvein and secondary venation flush or slightly prominent on both surfaces, ± brochidodromous, the reticulate tertiary venation evident on the lower surface, a dark gland at the apex of the midvein, sunken black glands within the areoles of the tertiary venation on the lower surface, and around the blade margin, the glands very obscure on the more mature coriaceous leaflets

Morphology Reproductive morphology Inflorescences

Inflorescence a short, erect, axillary or terminal, c- 30 – 60-flowered raceme held above the foliage, sometimes with secondary branching and thus paniculate, the rachis puberulous to pubescent to finely tomentose, with stellate-glandular trichomes intermixed (especially when young), or glabrous

Morphology Reproductive morphology Flowers

Flowers yellow, the pedicel 10 – 15 mm long, articulated at or just below its middle (5 – 7.5 mm below the calyx), the point of articulation slightly ridged and with a concentration of pale tangerine-coloured glandular trichomes, below the articulation glandular and glabrous to finely puberulous, above glandular and pubescent or puberulous, with stellate trichomes sometimes intermixed; bracts lanceolate to ovate-lanceolate, 4 – 5 × 2 mm, densely tomentose with matted trichomes together with a few subepidermal glands; calyx bright glossy green, upper and lateral lobes (5 –) 6 – 7.5 mm long, slightly reflexed, finely puberulous on both surfaces, a few subepidermal glands evident (these appearing as oil globules), lower calyx lobe 7 – 8 (– 9) mm long, the margin finely fimbriate, the fimbriae gland-tipped; standard petal sometimes speckled or streaked orangish red in its centre, suborbicular to broadly obovate to sub-panduriform, 11 – 12 × 8 – 10 mm (including a 2.5 – 3 mm long claw), the claw apex thickened on either side forming two erect, angular, sparsely gland-tipped ridges, the thickening of the claw far more pronounced than in the four lateral petals, a few subepidermal black glands embedded in the blade apex; the upper lateral petals suborbicular to elliptic or obovate, 11 – 12.5 × 8 – 11 mm (including a 2.5 – 3 mm long claw), the folded base of the blade running into the inrolled, thickened claw; the lower lateral petals suborbicular to elliptic-obovate, the blade asymmetric in relation to the claw position, 12 – 13 × 8 – 10 mm (including a 2 – 3 mm long claw), the folded base of the blade running into the inrolled, thickened claw; all petals densely covered with short-stalked or sessile glandular trichomes on their outer surfaces, all with a fine reticulate network of veins, the bases of the petal claws all pubescent on the outer surface; stamen filaments green, c- 11 – 12 mm long, the basal ⅔ - ¾ pubescent (the basal ¼ densely so) at least along the inner surface, an occasional short-stalked gland intermixed with the indumentum, anthers dull orangish green, 1.5 – 2 × 1 mm; ovary 6 – 7 mm long, moderately to densely puberulous to pubescent (with a mixture of short and longer hairs), with sessile to short-stalked glandular trichomes, stellate trichomes and stellate trichomes with a central stalked gland all intermixed, style c- 8 mm long with an indumentum as on the ovary, stigma a chamber fringed by a ring of papillae, the style apex slightly expanded directly below the stigma

Morphology Reproductive morphology Fruits

Fruit an explosively dehiscent, 5 – 6-seeded woody legume, yellowish green when unripe, turning mid orange-brown at maturity, 5.8 – 10.5 × 1.7 – 2.8 cm, the valves glabrous with subepidermal glands sometimes erupting as glandular pustules, occasionally with transverse orange-red resinous ducts and raised woody veins, the seeds separated by sub-woody partitions

Morphology Reproductive morphology Seeds

Seeds pale yellowish brown when fresh, mid brown and shiny when dry, broadly ovate to broadly elliptic, 10 – 16 × 7.5 – 13 mm

Distribution

Caesalpiniapluviosa var. maraniona is apparently common in the middle reaches of the upper Río Marañón Valley in northern Perú, in the Departments of Amazonas and Cajamarca. Most collections come from either the area between Celendín and Leimebamba, or from between Jaén and Bagua Chica. Map 1.

Ecology

In dry thorn scrub forest (this sometimes highly disturbed) and cactus forest (so called when members of the Cactaceae are dominant) on ‘desert slopes’ and in dry gullies of the Río Marañón Valley; c. 450 – 1160 m. Associated plants include Acacia macracantha Humb. & Bonpl. ex Willd., Coursetia cajamarcana, Parkinsonia praecox, Pithecellobium excelsum, Mimosa ctenodes, M. incarum, M. pectinatipinna Burkart (all Leguminosae), Browningia sp., Espostoa sp., Melocactus sp. and Rauhocereus sp. (Cactaceae), Eriotheca sp. (Bombacaceae), Capparis sp. (Capparidaceae), and Croton sp. (Euphorbiaceae).

Conservation

Although Caesalpiniapluviosa var. maraniona is restricted to the upper Río Marañón Valley of northern Perú, within the valley it occurs widely and is often abundant in secondary thorn scrub and thus, is apparently resilient to disturbance and given a conservation rating of Least Concern (LC).

Note

Flowering from January to April, fruiting from February to June. In phylogenetic analyses of molecular data (Sotuyo et al., unpublished), Caesalpiniapluviosa var. maraniona groups with other varieties of C. pluviosa and with C. eriostachys from Central America and México. The close relationship of C. pluviosa (all varieties restricted to South America) with C. eriostachys was previously demonstrated in the molecular analyses of Simpson et al. (2003) and Sotuyo et al. (unpublished). The new variety maraniona is most similar in leaf formula to varieties paraensis and sanfranciscana, but neither of those taxa extend into western South America and both have pedicels that are articulated directly below to no more than 2.5 mm below the calyx, in contrast to the pedicel articulation at 5 – 7.5 mm below the calyx in var. maraniona. The new taxon is also morphologically similar to C. gaumeri from Belize, the Yucatan Peninsula of México and western Cuba, and this relationship is also supported by unpublished molecular studies. C. gaumeri, however, has smooth grey bark, not the characteristic exfoliating papery bark of C. pluviosa var. maraniona. C. gaumeri also has smaller flowers with a standard petal 9 – 11 × 5 – 7 (– 10) mm (including a 3 – 4 mm long claw) in contrast to the standard 11 – 12 × 8 – 10 mm (including a 2.5 – 3 mm long claw) in C. pluviosa var. maraniona. The new variety is named after the Marañón Valley of northern Perú.