Stryphnodendron procerum 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 : 260-262

28. Stryphnodendron procerum Scalon , sp. nov.

( Fig. 8 )

—Type: BRAZIL. Amazonas, Maraã, Rio Japurá , margem esquerda, Lago Maraã, 29 October 1982, Amaral et al. 232 (holotype INPA 106613 !, isotypes K!, MG!, MO!, NY!, UB!, US!)

Diagnosis: Stryphnodendron procerum is morphologically related to S. excelsum , but differs by its conical petiolar nectary (vs. verruciform with an elongated base in S. excelsum ), 4–8 pairs of pinnae (vs. 8–11 pairs), 2–9 rachillae nectaries (vs. 1–3), tuft of trichomes on the lower surface usually absent, inconspicuous when present (vs. present and unilateral), ovary sparsely white-tomentose to white-tomentose, sometimes white-pubescent, rarely glabrous (vs. glabrous), prophylls deciduous (vs. late deciduous).

Trees ca. 33 m tall, the branches gray and reddish-brown with scattered white lenticels, lacking extrafloral nectaries, glabrous, ferruginous-pulverulent and yellow-pubescent, glabrescent, more densely towards the apex, the apex densely ferruginous-pulverulent and yellow-pubescent. Leaves with petioles 2.2–4 cm long, glabrous to sparsely ferruginouspulverulent, glabrescent, yellow-pubescent to sparsely yellow-pubescent only near the insertion of the proximal pair of pinnae, extrafloral nectary 1, inserted at 0.5–1.6 cm from the base of the petiole, 1.5–3 × 1–1.5 mm, conical; pinnae 4–8 pairs, subopposite to opposite, the insertion of each pair spaced in (0.6–) 1–2.3 cm; rachis striate, sparsely ferruginouspulverulent, yellow-pubescent only near the insertion of the pinnae, otherwise glabrescent; extrafloral nectaries 1–4, inserted at 1–5 mm below the distal pair of pinnae, ca. 1 × 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 (5–)7–14 pairs, the 2–3 proximal pairs of pinnae bearing fewer pairs of leaflets; rachillae sparsely yellow-pubescent to yellow-pubescent, very sparsely ferruginous-pulverulent, glabrescent, extrafloral nectaries 2–9, inserted at ca. 1 mm below the distal pair of leaflets, ca. 0.5 × 0.5 mm, verruciform; stipel deciduous, not seen; leaflets usually subopposite, opoosite towards the apex of the rachis, very rarely alternate, blade asymmetrical, usually oblong to oblong-rhombic, sometimes ovate, rarely elliptic (specially athe the proximal pairs of leaflets), the distal pairs usually widely obovate, sometimes obovate, (5–)6–16 × 4–9 mm, apex usually retuse, sometimes rounded, rarely truncate, margin sub-revolute, entire and puberule to pubescent, base asymmetrical, proximal side usually obtuse, sometimes widely rounded, at the distal pairs of leaflets usually acute, distal side narrowly rounded, chartaceous to subcoriaceous, discolor, upper surface nigrescent, glossy, subglabrous to sparsely puberule, lower surface lighter, opaque, subglabrous, sparsely puberule to puberule, unilateral tuft of trichomes on the lower surface of the leaflets usually absent, sometimes inconspicuous, not prolonged, venation brochidodromous, the nerves weakly evident on both surfaces, the midrib sulcate at the upper surface, prominent at the lower surface, the remaining nerves weakly prominent. Inflorescences of simple thyrsi, yellow; cymulae bearing (1–)2–4 spikes 8–14 cm long; bracts deciduous, not seen; peduncle 1–2.5 cm long, ferruginous-pulverulent to densely ferruginous-pulverulent, flattened to subcylindrical; rachis sparsely ferruginous-pulverulent and yellow-pubescent to densely yellow-pubescent, subcylindrical, ca. 1 mm thick. Flowers monoclinous and diclinous (only staminate flowers seen), color unknown; calyx campanulate, shortly apiculate, yellow-pubescent, ca. 1 mm long; corolla ca. 2 mm long, tubular, petals fused up to 2/3 of its length, glabrous to subglabrous at the tube, the lobes puberule to pubescent, acute, erect; stamens 3–5 mm long, anthers ca. 0.5 mm long, nectaries stipitate, conspicuous fold present at the dorsal side of the anthers, approximately the same length of the thecae; ovary sparsely white-tomentose to tomentose-tomentose, sometimes white-pubescent, rarely glabrous, shortly stipitate, stigma porate; prophylls deciduous, ca. 0.5 mm long, shell-shaped, yellow-pubescent. Fruits not seen.

Etymology: —The epithet of this new species refers to the latin word for “very tall”, or “high”, in reference to the size of the individuals that were registered in herbarium specimens.

Remarks: — Stryphnodendron procerum has typically yellow flowers, with indumentum covering calyx and corolla, and as the name suggests, are large-sized trees up to 33 m tall and 2.5 m in diameter. The species is also distinguished by having only 4–8 pairs of pinnae, small (0.5 × 0.5 mm) and verruciform extrafloral nectaries at the rachillae, found between almost all pairs of leaflets, whilst the extrafloral nectaries of the rachis are conical. The leaflets usually lack the unilateral tuft of trichomes on the lower surface, or they are inconspicuous when present, and the ovary is usually white-tomentose to sparsely white-tomentose, sometimes white-pubescent (rarely glabrous). S. procerum so far have been treated either as S. microstachyum , or S. guianense , although it does not have the glabrous flowers and cupuliform calyx characteristic of S. guianense , nor the conical extrafloral nectaries at the rachillae that are typical of S. microstachyum . This species belongs to the group of Amazonian multifoliolate taxa with medium-sized leaflets, and the species that are morphologically most similar to S. procerum are S. excelsum and S. conicum , which can be distinguished by the features listed on table 5. According to the holotype’s label (I.L. Amaral et al. 232), this species has a white and heavy wood, and the label in L.C. Procópio et al. 275 mentions that the tree exudates a sticky, honey-colored resin when cut.

Distribution and habitat: — Stryphnodendron procerum has a very restricted distribution in the Amazon region, known only in tropical rainforest areas of the Northwest Sector phytogeographic province, in periodically flooded areas. There are two registers of this new taxon collected in a legal protection area (Reserva de Desenvolvimento Sustentável Mamirauá), and although the labels of the specimens refer their occurrence in Manaus, this conservation unit is located between the Japurá, Solimões and Auti-Paraná rivers in Western Amazon instead.

Conservation: —Endangered (EN B2ab(ii,iii)) [AOO= 8.000 km 2, EOO not measurable]. The new species is known from only three records from two different locations, and although it occurs in a very restricted area, there are registers of S. procerum in legally protected areas (Mamirauá Sustainable Development Reserve), which is a favorable factor for its conservation.

Phenology: —The species was collected with flowers in October and fruits in May.

Additional specimens examined (paratypes): — BRAZIL. Amazonas: Manaus, Reserva de Desenvolvimento Sustentável de Mamirauá , 09 October 2000, fl., J.M. Brito 139 ( INPA, UB). Manaus, Estação Ecológica de Mamirauá, 06 May 2000, fr., L.C. Procópio et al. 275 (INPA, UB) .

Figures

FIGURE 8. Stryphnodendron procerum Scalon. A. Flowering branch. B. Detail of rachilla with extrafloral nectaries. C. Leaflet (adaxial side). D. Leaflet (abaxial side). E. Detail of apex of rachis with an extrafloral nectary. F. Detail of petiole with extrafloral nectary. G. Flower. H. Open flower exposing the pistil.