Stryphnodendron velutinum Scalon, 2022

Scalon, Viviane Renata, Paula-Souza, Juliana De, Lima, Alexandre Gibau De & Souza, Vinicius Castro, 2022, A synopsis of the genus Stryphnodendron (Fabaceae, Caesalpinioideae, mimosoid clade), Phytotaxa 544 (3), pp. 227-279 : 269-271

34. Stryphnodendron velutinum Scalon , sp. nov. ( Fig. 10 )

— Type: BRAZIL. Minas Gerais, Unaí, fragmento de cerradão no km 11 da rodovia Unaí / Paracatú , elev. 650 m, 16°15’S, 46°45’W, 22 October 1995, Pereira & Alvarenga 2943 (holotype IBGE 36575 !, isotypes CEN!, NY!, RB!, RFA!)

Diagnosis: Stryphnodendron velutinum is similar to S. adstringens , but it has velutinous petioles (vs. glabrous to very sparsely pubescent in S. adstringens ); fusiform, usually immersed, sometimes slightly prominent petiolar nectary (vs. verruciform with an elongated base), 2–4 rachillae nectaries (vs. 1), blades puberule-velutinous on both surfaces, more densely at the lower surface (vs. glabrous), glabrous to white-pulverulent ovary, glabrescent (vs. glabrous), prophylls late deciduous, densely yellow-tomentose and ferruginous-pulverulent (vs. deciduous and tomentose) and flat-compressed fruits (vs. turgid).

Trees 4–5m tall, the branches erect, lenticellate, lacking extrafloral nectaries, velutinous, glabrescent, yellowvelutinous at the apex. Leaves with petioles 6.5–8.5 cm long, velutinous, extrafloral nectary 1, inserted at 0.3–0.7 cm from the base of the petiole, 3–4 × 0–0.5 mm, fusiform, usually immersed, sometimes slightly prominent, darkened; pinnae 5–6 pairs, subopposite to opposite, the insertion of each pair spaced in 2–3 cm; rachis striate, velutinous; extrafloral nectaries 1–2, inserted at (1–) 3–5 mm below the distal pairs of pinnae, 1–2 × 0–0.5 mm, usually fusiform with the central part circular e slightly elevated, sometimes rounded, darkened; stipels deciduous, not seen; 2nd degree petiolules 0.2–0.3 mm long, color not evident, densely yellow-velutinous; leaflets 5–7 pairs, the proximal and distal pairs of pinnae bearing fewer pinnula; rachillae velutinous, extrafloral nectaries 2–4, inserted 0.5–2 mm below the distal pair of leaflets, (0.5–)1 × 0.2–0.5 mm, verruciform to fusiform, darkened; stipel deciduous, not seen; leaflets usually alternate, subopposite only at the distal pair of leaflets, blade slightly asymmetrical, usually orbicular, sometimes widely elliptic to ovate, distal leaflets usually obovate, (11–)20–26 × (11–) 16–24 mm, apex usually asymmetrical, emarginate, rarely retuse, margin sub-revolute, entire and velutinous, base asymmetrical, the proximal side usually truncate, sometimes widely rounded, distal side usually rounded, the proximal side acute and distal side rounded at the distal pairs of leaflets, membrano-chartaceous, subconcolor, upper surface slightly darker, puberule-velutinous, lower surface lighter, densely puberule-velutinous, opaque on both surfaces, unilateral tuft of trichomes on the lower surface of the leaflets present, usually prolonged up to the 2nd or 3rd pair of secondary nerves, venation brochidodromous, the nerves clearly evident and weakly prominent at the upper surface, evident and prominent at the lower surface. Inflorescences of simple thyrsi, whitish; cymulae of solitary to geminate spikes, spikes 9.5–14 cm long; bracts deciduous, not seen; peduncle 1–2.5 cm long, ferruginous-pulverulent and velutinous, subcylindrical; rachis densely yellow-velutinous, very sparsely ferruginous-pulverulent, cylindrical, ca. 2 mm thick. Flowers monoclinous, color unknown; calyx campanulate, apiculate, glabrous to rarely subglabrous, ciliate only at the apex of the lobes, ca. 1.5 mm long; corolla 4–4.5 mm long, tubular-campanulate, fused up to 1/2 of its length, glabrous, lobes acute, erect; stamens 8–9 mm long, anthers ca. 0.8 mm long, nectaries stipitate, conspicuous fold present at the dorsal side of the anthers, only above the insertion of the filament; ovary shortly stipitate, glabrous to white-pulverulent, glabrescent, stigma porate; prophylls deciduous, ca. 1 mm long, shell-shaped, densely yellow-tomentose and ferruginous-pulverulent. Fruit a sessile nucoid legume, straight to slightly curved, apex acute to rounded, base attenuate, flat-compressed, seeds slightly prominent, 7–9 × 1.3–1.7 cm, valves coriaceous, dark brown, reddish, ferruginous-pulverulent, glabrescent. Seeds 6–8, not seen.

Etymology: —The epithet of this new species refers to the very characteristic indumentum that covers the vegetative parts of the plant.

Remarks: — Stryphnodendron velutinum is most similar to S. adstringens in respect to vegetative (number of pairs of pinnae and leaflets and shape) and also reproductive characters (flower color, size of spikes and congested aspect of the inflorescences, stamen size), but shows some unique features that support its recognition as a separate taxon, listed on table 6.

This new species also shows the fusiform petiolar extrafloral nectaries that are usually immersed to sometimes slightly prominent and darkened, as seen in S. holosericeum , but the leaves have fewer pairs of pinnae and leaflets, besides being mostly larger and velutinous on both surfaces.

Distribution and habitat: —This new species is only known from a very small area in Northeastern Minas Gerais, with a few registers collected in “degraded cerrado” or “cerradão” on the roadside near the municipality of Unaí, just a few kilometers from the limits with Goiás state. Stryphnodendron velutinum grows on sandy soils, as observed in situ.

Conservation: —Endangered (CR B1ab(i,iii)+2ab(ii,iii) [AOO= 8.000 km 2, EOO= 83.263 km 2]. Recent visits to the area indicated that the individuals of this species are very sparse and the populations are subject to intense anthropogenic pressure, as suggested from herbarium collections.

Phenology: — Stryphnodendron velutinum was collected with flowers in October and with fruits in February.

Additional specimens examined (paratypes): — BRAZIL. Minas Gerais: Unaí, lado esquerdo do Trevo Unaí / Bonfinópolis / Garapuava , 06 October 1994, fl., B.A.S. Pereira & D. Alvarenga 2659 ( CEN, IBGE, NY, RB) . Unaí , Fz. Guará, July 2003, sterile, A. Menezes Jr. s.n. ( RB 388697) . Unaí , margem direita da rodovia MG 188 (Unaí-Paracatu), ca. 7.3km da cidade, 16°26’07.7”S, 46°53’10.3”W, 03 February 2005, fr., V.R. Scalon et al. 719 ( ESA) .

Figures

FIGURE 10. Stryphnodendron velutinum Scalon. A. Flowering branch. B. Detail of rachilla with extrafloral nectaries. C. Leaflet (adaxial side). D. Leaflet (abaxial side). E. Detail of petiole with extrafloral nectary. F. Detail of inflorescence rachis. G. Flower. H. Pistil.