Stryphnodendron platycarpum 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 : 254-257

23. Stryphnodendron platycarpum Scalon , sp. nov. ( Fig. 7 ).

—Type: PERU. Loreto, Requena , bosque inundable, ca. 800m de la Base Yarina, margen derecha del caño Yarina, en la Zona Reservada del río Pacaya, margen izquierda del Río Ucayali, 22 March 1977, Encarnación E –1071 (holotype G 0252076!, isotypes K!, US!)

Diagnosis: Stryphnodendron platycarpum is morphologically related to S. guianense , but differs by its verruciform petiolar nectary ca.1.5 × 0.5 mm (vs. verruciform with an elongated base, 2–3 × 1.5–2 mm in S. guianense ); conical rachis nectary (vs. verruciform); calyx glabrous, ciliate only at the apex of the lobes, shortly apiculate (vs. glabrous to rarely subglabrous, usually ciliate, lobes not evident), fruits 11–13.5 × 2.2–2.7 cm (vs. 5.5–7 × 1.1–1.4 cm).

Small-sized trees (height unknown), the branches lenticellate, lacking extrafloral nectaries, glabrous, ferruginouspulverulent, glabrescent, ferruginous-pulverulent. Leaves with petioles 3–4.5 cm long, ferruginous-pulverulent, glabrescent, extrafloral nectary 1, inserted at 1.3–2 cm from the base of the petiole, ca. 1.5 × 0.5 mm, verruciform; pinnae 7–9(–10) pairs, subopposite to opposite, the insertion of each pair spaced in 1–1.5 cm; rachis striate, sparsely ferruginous-pulverulent and sparsely yellow-pubescent, glabrescent; extrafloral nectaries 2–4, inserted at 2–3 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–)8–11 pairs; rachillae yellowpubescent, glabrescent, extrafloral nectaries 2–9, inserted at 1–2 mm below the distal pair of leaflets, ca. 0.5 × 0.5 mm long, verruciform; stipel deciduous, not seen; leaflets usually alternate, or usually subopposite near the base or the apex of the rachillae, blade asymmetrical, usually oblong-rhombic, sometimes elliptical at the proximal pairs, obovate at the distal pairs, (4–)6–11 × (–3) 5–7 mm, apex usually rounded, rarely retuse, margin flat, slightly thickened, entire and puberule, base asymmetrical, the proximal side of the blade usually obtuse, sometimes widely rounded, distal side usually narrowly rounded, rarely acute, the base of distal pairs sometimes acute, membranaceous-chartaceous, discolor, upper surface usually glaucous, opaque, glabrous, lower surface lighter, opaque, puberule, unilateral tuft of trichomes on the lower surface of the leaflets present, not prolonged, venation brochidodromous, the nerves not visible and immersed at the upper surface, evident and prominent at the lower surface. Inflorescences of simple thyrsi, color unknown; cymulae of solitary to ternate spikes, spike 7.2–7.7 cm long; bracts deciduous, not seen; peduncle 1.5–1.7 cm long, ferruginous-pulverulent, cylindrical; rachis yellow-pulverulent, sparsely yellow-pubescent, cylindrical, ca. 1 mm thick. Flowers monoclinous, pinkish; calyx campanulate, shortly apiculate, glabrous, ciliate only at the apex of the lobes, ca. 0.5 mm long, color unknown; corolla ca. 2 mm long, campanulate, petals fused up to 1/2 of its length, glabrous, color unknown, lobes acute, erect; stamens ca. 3.5 mm long, color unknown, anthers ca. 0.3 mm long, nectaries stipitate, conspicuous fold present at the dorsal side of the anthers, ca. the same size as the thecae; ovary shortly stipitate, glabrous, stigma porate; prophylls deciduous, ca. 0.5 mm long, shell-shaped with an elongated base, pubescent. Fruit sessile, nucoid legume, straight to very rarely slightly curved, apex apiculate, base attenuate to acute, flat-compressed with slightly prominent seeds when immature, mature fruit not seen, 11–13.5 × 2.2–2.7 cm, valves coriaceous, dark brown to reddish brown, ferruginous-pulverulent, glabrescent. Seeds 8–10, not seen.

Etymology: —The epithet “ platycarpum ” refers to the Greek word meaning abnormally flattened and enlarged fruits.

Remarks: — Stryphnodendron platycarpum forms the larger fruits among the Amazonian multifoliolate taxa, with medium-sized leaflets and glabrous corolla (rarely subglabrous). Though the only fruiting sample available does not refer their degree of maturity, only mentioning “legumbre carnoso subterminal”, the fruits are flat-compressed with a prominent margin and slightly prominent seeds, which is more frequently observed in this genus for fruits that are not completely mature and might indicate the phenological phase of this specimen, reinforcing the size discrepancy between this new species and the remainder of its group. This species has been referred as a “arbusto bejucoso”, that is, a prostrate bush growing along the riverside; however, most specimens describe it as arboreous individuals, without mentioning the height.

Stryphnodendron platycarpum is morphologically close to S. guianense , from which it differs by its flowers with shortly apiculate calyx, verruciform and reduced petiolar extrafloral nectaries and extrafloral nectaries of the rachis conical. The species are also distinct in their geographical distributions, S. guianense being found at Eastern Amazon, whilst S. platycarpum occurs at Western Amazon. Another similar species that occurs sympatrically with S. platycarpum , S. microstachyum has only 1-2 conical extrafloral nectaries at the rachis, a larger verruciform petiolar extrafloral nectary with an elongated base, and arboreous habit with medium to large sized individuals, as well as fruits usually curved, subturgid with prominent seeds. Further distinctive features are listed on table 4.

Besides having the largest fruits (11–13.5 × 2.2–2.7 cm) within this group, the new species is easily recognized by its pinkish flowers with ciliate, shortly apiculate calyx lobes and campanulate, glabrous corolla. Diagnostic vegetative features include verruciform and reduced (0.5 × 0.5 mm) extrafloral nectaries of the rachillae inserted between almost all pairs of leaflets, and reduced petiolar extrafloral nectary (ca. 1.5 × 0.5 mm).

Distribution and habitat: —The new species is known only in Western Amazon (phytogeographic province Sector Southwest), in the Iquitos region in Peru. Pristine areas of this region are covered by different types of forests and all of them show great species richness, including the periodically flooded forests known as tahuampa (Gentry, 1989). The specimens collected so far are very brief on the description of the collecting sites, but samples collected near the Ucayali river indicated a bosque inundable, or flooded forest, cited by Gentry (1989) as common in the region.

Conservation:—Data Deficient (DD) [AOO= 8.000 km 2, EOO not measurable]. The new species is known to occur in just a few locations within a very restricted area, with no recent collections and registers of populations in conservation units. However, the information currently available with regards to the threats in the area is not sufficient to allow an accurate assessment of the conservation status of the taxon.

Phenology: —This species was collected with flowers in October and fruits in March.

Additional specimens examined (paratypes): — PERU. Depto. Loreto: Mishuyaco, near Iquitos , 100m, October-November 1929, fl., G. Klug 47 ( NY). Iquitos, 26 October 1927, fl., A. Ducke s.n. ( RB 20182 , K, US).

Figures

FIGURE 7. Holotype of Stryphnodendron platycarpum Scalon in G.