Stryphnodendron conicum 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 : 237-239

4. Stryphnodendron conicum Scalon , sp. nov. ( Fig. 3 ).

—Type: BRAZIL. Pará, Oriximiná, Área de Mineração Rio Norte , 5 km da vila residencial, 1°28’S, 56°23’W, 11 November 1987, C.A. Cid Ferreira 9548 (holotype INPA 155605 !, isotypes F!, K!, MO!, NY!, RB!, US!)

Diagnosis: Stryphnodendron conicum resembles S. guianense , but differs by its conical petiolar nectaries, with 3 distinct layers (vs. verruciform with an elongated base), rachis nectary conical to verruciform with an elongated base (vs. verruciform), rachilla nectary conical (vs. verruciform), tuft of hairs on the lower surface of the blades absent (vs. usually present, sometimes inconspicuous), calyx yellow-pubescent with apiculate lobes (vs. glabrous to rarely subglabrous with no evident lobes) and corolla pubescent at the lobes (vs. glabrous).

Treelets to trees (3) 4–10 m tall, the branches lenticellate, lacking extrafloral nectaries, ferruginous-pulverulent, glabrescent. Leaves with petioles 3.7–5 cm long, ferruginous-pulverulent, very sparsely yellow-pubescent towards the apex, extrafloral nectary 1, inserted at (0.8–) 1–1.6 cm of the base of the petiole, 3.5–4 × 1–1.5 mm, conical (with 3 distinct layers); pinnae (8–)9–11(–13) pairs, subopposite to opposite, the insertion of each pair spaced in 1–1.8 cm; rachis striate, ferruginous-pulverulent and sparsely yellow-pubescent; extrafloral nectaries 1–3(–4), inserted immediately below the distal pair of pinnae, ca.1.5 × 1.5 mm, conical to verruciform with an elongated base; stipels deciduous, not seen; 2 nd degree petiolules ca. 1 mm long, the same color as the upper surface of the blade, yellowpuberule; leaflets (6–)9–14 pairs, the proximal 2–3 pairs of pinnae bearing fewer pairs of leaflets; rachillae yellowpubescent, very sparsely ferruginous-pulverulent, extrafloral nectaries 1–3, inserted at ca. 1 mm below the distal pair of leaflets, ca.1 × 1 mm, conical, present only at the 2–3 proximal pairs of pinnae; stipel late deciduous, linear, ca. 0.5 mm long; insertion of leaflets usually alternate, very rarely subopposite, blade usually elliptic to elliptic-ovate, rarely oblong or circular, the ones of the distal pairs usually widely obovate, (5–)7–13 × (–4) 5–8 mm, apex usually retuse, sometimes rounded, rarely truncate, at the distal pairs of pinnnulae usually emarginate, margin sub-revolute, entire, puberule, base asymmetrical, the proximal side usually truncate, sometimes widely rounded, at the distal pairs of leaflets usually acute, the distal side narrowly rounded, chartaceous, discolor, the upper surface dark, glossy, sparsely puberule, the lower surface lighter, opaque, puberule, unilateral tuft of trichomes on the lower surface of the leaflets absent, venation brochidodromous, the nerves evident and prominent on both surfaces. Inflorescences of simple thyrsi, yellow to greenish-yellow; cymulae of solitary geminate to ternate spikes, spike (8–) 12–14 cm long; bracts deciduous, not seen; peduncle 1.1–3.5 cm long, ferruginous-pulverulent, subcylindrical; rachis sparsely ferruginous-pulverulent, densely yellow-pubescent, rarely yellow-pubescent, cylindrical, ca. 0.8 mm thick. Flowers monoclinous, color unknown; calyx tubular-campanulate to campanulate, apiculate, yellow-pubescent, ca. 1 mm long, color unknown, corolla ca. 2 mm long, campanulate, petals fused up to 2/3 of its length, subglabrous to sparsely pubescent at the tube, the central part of the lobes pubescent (the indumentum usually does not reach the edge), lobes acute, erect, color unknown; stamens 3.5–4 mm long, color unknown, anthers ca. 0.3 mm long, nectaries stipitate, conspicuous fold present at the dorsal side of the anthers, approximately the same length as the thecae; ovary shortly stipitate, stigma porate, sparsely puberule to glabrous; prophylls deciduous, ca. 0.5 mm long, shell-shaped, yellow-pubescent. Fruit a sessile, nucoid legume, mature fruits not seen, immature fruits straight, flat-compressed, seeds prominent, 6–7 × 1 cm, valves coriaceous, reddish-brown, densely ferruginous-pubescent. Seeds not seen.

Etymology: —The name of this new species refers to the conical shape of the rachillae´s floral nectaries which is very distinct from other morphologically close species.

Remarks: — Stryphnodendron conicum vegetatively resembles all the multifoliolate Amazonian species with medium-sized leaflets, yellowish inflorescences and indumentum in calyx and corolla (table 5). The specimens of this new species have often been named as S. guianense based on blade shape and the presence of unilateral tuft of trichomes on its lower surface, since the only identification key to Amazonian species of the genus to date ( Martins, 1981) used vegetative characters. However, by the time this key was published the concept of S. guianensis showed many morphological and nomenclatural problems, and the circumscription of the species was usually broadened and often mistakenly included other species of Stryphnodendron . In fact, the analysis of a large number of specimens has showed that the tuft of trichomes are only rarely absent on the lower surface of the blades of S. guianense (vs. absent in S. conicum ), and the new species shows other distinct characteristics such as extrafloral nectaries of the rachis conical to verruciform with an elongated base, calyx yellow-pubescent and indumentum ed corolla. Moreover, the leaf primordia at the apex of the branches show very developed petiolar extrafloral nectaries, almost the size of a mature leaf´s, a very characteristic feature and useful in the identification of the specimens.

Stryphnodendron conicum can also be confused with S. pulcherrimum , with which sometimes occurs sympatrically, but the new species shows larger and fewer leaflets, evident nerves on both surfaces of the blade, extrafloral nectaries of the rachillae conical and the calyx about half the length of the corolla. Stryphnodendron microstachyum , another morphologically close species, has flowers with the calyx usually glabrous to subglabrous (very rarely sparsely pubescent) and a glabrous to rarely subglabrous corolla, besides shorter inflorescences (usually 6.5–10 cm long) and vegetatively, the leaflets of this species are usually widely oblong, oblong-rhombic to oblongovate, whereas in S. conicum they are elliptic to elliptic-ovate.

Distribution and habitat: —This taxon is restricted to areas of campinas on sandy soil, near watercourses, in the region of the lower Trombetas river in Pará state (municipalities of Porto Trombetas and Oriximiná). The area of occurrence of this taxon corresponds to the phytogeographic province Jari-Trombetas.

Conservation: —Vulnerable (VU B2ab(ii,iii)) [AOO= 8.000 km 2, EOO not measurable]. The species occurs in a very restricted area in Amazonia that is subject to intensive mining activities, and preliminarily this would assign it the status of Critically Endangered. However, there are at least six records of the new species within its limited distribution (one of them in a conservation unit, FLONA Saracá), and based on the available data we assign Stryphnodendron conicum the status of Vulnerable.

Phenology: —Specimens with flowers were collected from September to January and with immature fruits in July, mature fruits from September to November.

Additional specimens examined (paratypes): — BRAZIL. Pará : Oriximiná , Porto Trombetas, estrada C– Leste, 11 November 2005, fl./fr., R.D. Ribeiro et al. 542 ( RB) . Oriximiná , FLONA Saracá–Taquera / IBAMA, Porto Trombetas, 16 January 2003, fl., R.P. Salomão et al. 981 ( MG) . Oriximiná , Rio Trombetas, margem da estrada, Mineração Santa Patrícia, 08 July 1980, im.fr., C.A. Cid et al. 1360 ( INPA, MG, MO, NY) . Oriximiná , BR 163, estrada que dá acesso a Perimetral Norte, a 14 km da Cachoeira Porteira, 09 September 1986, C.A. Cid Ferreira et al. 7637, im.fr. ( INPA, MO, NY) . Porto Trombetas , Estrada da Mina, lado esquerdo, beira da estrada, 20 November 1985, E. Soares 31, fl. ( INPA) . Rio Trombetas , Monte Branco, jazida de Bauxita da Alcoa-Mineração, 06 October 1982, fl., J. Revilla et al. 6960 ( INPA) .

Figures

FIGURE 3. Holotype of Stryphnodendron conicum Scalon in INPA.