A synopsis of the genus Stryphnodendron (Fabaceae, Caesalpinioideae, mimosoid clade) Author Scalon, Viviane Renata 0000-0001-7000-6641 Universidade Federal de Ouro Preto, Herbário OUPR. Campus Morro do Cruzeiro s. n., 35400 - 000, Ouro Preto / MG, Brazil. vrscalon @ gmail. com; https: // orcid. org / 0000 - 0001 - 7000 - 6641 vrscalon@gmail.com Author Paula-Souza, Juliana De Universidade Federal de Santa Catarina, Departamento de Botânica / CCB. Rua Eng. Agronômico Andrei Cristian Ferreira 216, 88040 - 535, Florianópolis / SC, Brazil. Author Lima, Alexandre Gibau De Universidade de São Paulo, ESALQ. Av. Pádua Dias 11, 13418 - 900, Piracicaba / SP, Brazil. & Escola Nacional de Botânica Tropical, Jardim Botânico do Rio de Janeiro, Rua Pacheco Leão 2040, 22460 - 030, Rio de Janeiro / RJ, Brazil. alegibau @ gmail. com. Author Souza, Vinicius Castro Universidade de São Paulo, ESALQ. Av. Pádua Dias 11, 13418 - 900, Piracicaba / SP, Brazil. text Phytotaxa 2022 2022-05-03 544 3 227 279 http://dx.doi.org/10.11646/phytotaxa.544.3.1 journal article 55680 10.11646/phytotaxa.544.3.1 f125f93d-3a5b-48a3-9561-4ebee258e3d6 1179-3163 6520280 21. Stryphnodendron orinocense Scalon , sp. nov. ( Fig. 6 ) —Type: VENEZUELA . Território Amazonas , Rio Orinoco , along left bank of river just below mouth of Rio Ventuari , 125–150 m , 16 June 1959 , Wurdack & Adderley 42999 ( holotype IAN 114608 !, isotypes F!, IAN! K!, NY!, U!, US !) Diagnosis: Stryphnodendron orinocense is morphologically similar to S. guianense , but vegetatively it differs by its conical rachis nectary ca. 1 × 1mm ( vs. verruciform, ca. 0.5 × 0.5 mm ), prophylls late deciduous, yellow-pubescent ( vs. deciduous and pubescent). Reproductively S. orinocense is distinguished by its shortly apiculate calyx ( vs. inconspicuous lobes); corolla usually tubulate, rarely tubulate-campanulate 3–3.5 mm long, with petals fused up to 2/3 of its length ( vs. campanulate 2mm long, fused at 1/2 of its length), and longer stamens 5–6mm ( vs. 3–3.5 mm ). FIGURE 6 . Holotype of Stryphnodendron orinocense Scalon in IAN. Trees 8–10 m tall, the branches lenticellate, lacking extrafloral nectaries, ferruginous-pulverulent, sparsely pubescent, glabrescent, ferruginous-pulverulent at the apex. Leaves with petioles 3.5–4.2 cm long, ferruginouspulverulent, glabrescent, sparsely yellow-pubescent on the ventral surface, extrafloral nectary 1, inserted at ca. 1 cm from the base of the petiole, ca. 4 × 1 mm , verruciform with an elongated base; pinnae (5–)7–8(–10) pairs, subopposite to opposite, the insertion of each pair spaced in 1.5–2 cm ; rachis striate, ferruginous-pulverulent and sparsely yellowpubescent, glabrescent at the dorsal region; extrafloral nectaries (1–)2, inserted at 2.5–3 mm below the distal pair of pinnae, 1–1.5 × 1 mm , conical; stipels deciduous, not seen; 2nd degree petiolules ca. 1 mm long, the same color as the upper surface of the blade, yellow-pubescent; leaflets 8–11 pairs; rachillae sparsely ferruginous-pulverulent and yellow-pubescent, glabrescent on the dorsal surface, extrafloral nectaries 1–2, inserted 1–2 mm below the distal pair of leaflets, 1 × 1 mm long, verruciform; stipel deciduous, not seen; insertion of leaflets usually alternate, frequently subopposite near the apex and base of the rachillae, blade asymmetrical, usually widely oblong to oblong-rhombic, the ones of the proximal pairs sometimes elliptic, the distal pairs usually obovate, rarely cordiform, (8–)10–15 × (6–) 8–11 mm , apex usually retuse to rounded, at the distal pairs of leaflets usually emarginate, margin sub-revolute, entire and puberule, base asymmetrical, the proximal side of the blade usually widely rounded, sometimes obtuse, at the distal pairs usually acute, distal side usually narrowly rounded to acute, subcoriaceous, discolor, upper surface nigrescent, glabrous to subglabrous, lower surface lighter, puberule, unilateral tuft of trichomes on the lower surface of the leaflets present, not prolonged, opaque on both surfaces, venation brochidodromous, the nerves weakly evident and immersed in the upper surface, evident and prominent on the upper surface. Inflorescences of simple thyrsi, color unknown; cymulae of geminate to ternate spikes, spikes 9–14 cm long; bracts deciduous, not seen; peduncle 1–2.5 cm long, ferruginous-pulverulent, subcylindrical; rachis sparsely ferruginous-pulverulent and yellow-pubescent, cylindrical, ca. 1 mm thick. Flowers monoclinous, white; calyx crateriform, shortly apiculate, glabrous to subglabrous, ca. 0.5 mm long, white; corolla 3–3.5 mm long, tubular or rarely tubular-campanulate, petals fused up to 2/3 of its length, glabrous, color unknown, lobes acute, erect; stamens 5–6 mm long, filament color unknown, anthers ca. 0.3 mm long, color unknown, nectaries stipitate, conspicuous fold present at the dorsal side of the anthers, approximately the same size of the thecae; ovary shortly stipitate, glabrous, style color unknown, stigma porate; prophylls late deciduous, ca. 0.5 mm long, shell shaped, yellow-pubescent. Mature fruits not seen. Etymology: —The epithet “ orinocense ” refers to the river in Venezuela along which the new species grows. Remarks: — Stryphnodendron orinocense is morphologically similar to S. guianense , from which it differs by a series of vegetative and reproductive features summarized on table 4. Additionally, the two species show distinct geographical distributions, S. orinocense occurring in a much narrower area around the Orinoco River in Northwestern Amazonia. Distribution and habitat: — Stryphnodendron orinocense is only known from sites along the Orinoco river in Southern Venezuela , in the Northwest Sector phytogeographic province of the Amazon region. Conservation: —Data Deficient (DD) [AOO= 8.000 km 2 , EOO not measurable]. There are no recent collections of S. orinocense and it is known from a very reduced area. Current data about in situ populations of Stryphnodendron orinocense are not available, as well as information about threats in the area, hindering a precise assessment of its conservation status. Phenology: —The species was collected with flowers in May, June and August and with immature fruits in August. Additional specimens examined ( paratypes ): — VENEZUELA . Território Amazonas : Cano Cupaven , Rio Orinoco at mouth of Rio Atabapo , 11 May 1954 , fl., J.S. Level 75 ( RB , F, US, NY ) . Atabapo , alrededores de Caserío Guahibo “La Venturosa”, ribera del Orinoco , a 3 km al oeste de Santa Bárbara del Orinoco , 118 m , 03°56’N , 67°09’W , 12 August 1982 , fl./im.fr, F. Guanchez 1867 ( NY ) .