Plukenetia megastyla, Cardinal-McTeague & Gillespie, 2020

13. Plukenetia megastyla Card. -McTeag. & L.J.Gillespie sp. nov. TYPE: BOLIVIA. Depto. Santa Cruz, Prov. Guarayos (formerly Prov. Nuflo de Chavez ), 4 km N of Perseverencia, [-14.68333°, -62.80000°], 275 m, 9 September 1990, M.H. Nee 38682 (holotype: NY! [barcode 02286564]; isotype: MO! [accession 3816603, barcode MO-2001411 ]) .

Similar to P. brachybotrya Müll.Arg. and P. brevistyla Card. - McTeag. & L.J.Gillespie, but differs by having an oblong-obovoid stylar column with a truncate apex, 2.6–4.4 mm long.

Monoecious vines to slender lianas; stems erect or twining; older stems light brown and tan when dry, to; 5 mm in diam, striate, glabrate; younger stems smooth to striate, puberulous. Leaves alternate, evergreen; stipules narrowly triangular to deltoid, 0.3–1 mm long, persistent; petioles with thickened, often purplish, pulvinus-like regions at the base and apex, entire petiole 0.7–3.5 cm long, glabrate except sparsely puberulous when young; blades simple, narrowly elliptic to elliptic, oblong-elliptic, oblanceolate-elliptic, or obovate-elliptic (rarely ovate-elliptic), 7–19.8 3 1.8–7.5 cm, thick-chartaceous, both surfaces glabrate except sparsely puberulous on abaxial major veins when very young, base cuneate to obtuse, margins remotely serrulate, apex usually cuspidate, sometimes acuminate or attenuate, tip 0.4–1.6 cm long; venation pinnate, primary vein 1, secondary veins 5–7(–9) on each side of the midrib, weakly brochidodromous, tertiary veins percurrent, sometimes reticulate towards the midrib; stipels and glandular knobs absent adaxially at petiole apex; adaxial basilaminar extrafloral nectaries 2, narrowly to broadly oblong-elliptic, obovate, round-deltoid, or sometimes irregularly obtriangular, rarely with an additional smaller nectary above, 1.0–2.4 3 0.4–1.7 mm; abaxial laminar extrafloral nectaries (3–)6–14 per side (rarely absent), 0.2–0.7 mm in diam, near the margins on distal 9/10th to 4/fifth of the blade, adaxial laminar nectaries absent. Inflorescences axillary, bisexual racemose thyrses, 0.6–3 cm long, 1(2)/axil; peduncle absent (rarely 0.2–0.3 mm long); axes very sparsely to moderately puberulous throughout (sometimes more puberulous distally); staminate bracts ovate to broadly ovate, 0.4–1.1 mm long, puberulous (sometimes only along the margins and at the apex); pistillate bracts ovate, sometimes deltoid, (0.3–) 0.7–1 mm long, sparsely to densely puberulous; staminate flowers numerous, distal, 1–3(4)/node in condensed cymules (appearing short racemose if 3–4 flowers); pistillate flowers 1, basal (may appear to arise from the leaf axil), usually fallen or in fruit when staminate flowers are at or near anthesis. Staminate flowers: pedicel 12.8–14.8 mm long at anthesis, sparsely puberulous (densely when young); bud subglobose to ovoid, sometimes depressed and wider than long, apex rounded; sepals 3–4, incurved to spreading at anthesis, ovate to broadly ovate, 1–2.4 3 0.5–1.7 mm, apex obtuse, abaxial surface sparsely to moderately puberulous; receptacle subglobose to globose, fully covered with anthers; nectary an extrastaminal annular ring, upper surface sometimes undulate or uneven; androecium subglobose, 0.6–0.9 3 0.8–1.3 mm, stamens 20–30, filaments absent, anther sacs ellipsoid, dehiscing longitudinally. Pistillate flowers: pedicel (comprising cyme axis and true pedicel) 12.9–24.7 mm long, glabrate to sparsely puberulous; sepals 4, triangular, sometimes deltoid to broadly triangular, 0.5–1.2 3 0.4–0.7 mm, puberulous; ovary 4-lobed, 0.8–1.7 3 1–2 mm, lobes rounded and laterally compressed, glabrate except puberulous along midline of the lobe,conspicuous wings or horns absent;styles 4, entirely connate into an oblong-obovoid column, 2.6–4.4 3 2.6–3.7 mm, base constricted and 0.9–1.6 mm wide, apex truncate, with a central dimple when young, unlobed distally, glabrate; stigmas 4, light yellow-brown/tan or purple-red when dry, round-deltoid to circular, 0.8–1.1(2) mm long each, smooth. Fruits 4-lobed capsules, 0.7–1.1 3 1–1.6 cm, surface irregularly verrucose, glabrous or glabrate, each carpel lobe subglobose, usually with a short tubercle 0.4–1.4 mm long, sometimes unornamented; stylar columns persistent, oblong-obovoid, apex truncate and dilated; pedicel (comprising cyme axis and true pedicel) (12) 25–35 mm long. Seeds broadly lenticular, laterally compressed, elliptic to circular in outline, 4.8–5.2 3 5–5.9 3 3.8–4.2 mm, surface light to golden brown, sometimes with dark brown irregular splotches, weakly rugulose; testa persistent. Figure 8 View FIG .

Pollen —Tricolpate, oblate spheroidal (P/ E 5 0.88 –1.1), polar axis 32.9–45 m m, equatorial axis 31–51 m m; amb subcircular; colpi broad, margins uneven and jagged; tectum coarsely reticulate (voucher: Sperling et al. 6161 CAN).

Etymology —The specific epithet is derived from mega - (Greek, large or great) and -styla (Latin, -styled), and refers to the large stylar columns that differentiate this from similar species.

Distribution, Habitat, and Phenology —This species is known from two disjunct ranges in the southern Amazon basin: 1) Brazil, in southeastern Pará; and 2) Bolivia, in eastern Beni and Santa Cruz, and Brazil, in western Mato Grosso ( Fig. 6 View FIG ). They are slender lianas climbing on trees in terra firme rainforest with high canopies, growing in primary or disturbed primary forest along trails or forest edges, on flat lands or low hills from 140–738 m elevation. Flowering and fruiting specimens were collected from February to November in Pará and from August to November in Mato Grosso and Bolivia.

Discussion — Plukenetia megastyla is morphologically similar to P. brevistyla but differs by having thick oblong-obovoid stylar columns, 2.6–4.4 mm long ( Fig. 8 View FIG ), petioles with thickened, often purplish, pulvinus-like regions at the base and apex, and thick-chartaceous leaf blades, compared to short depressed-subglobose stylar columns, 0.3–1 mm long ( Fig. 5 View FIG ), petioles with more or less uniform thickness (sometimes darker in colour at the base and apex), and subcoriaceous leaf blades in P. brevistyla . Additionally, the annular nectary of P. megastyla appears to be consistently present ( Fig. 8G View FIG ), whereas the nectary of P. brevistyla is variable and can be annular, 3-lobed, or not evident. Both species are distributed in the Amazon basin, with P. megastyla along the southern boundary of the region and P. brevistyla near the main stem of the Amazon River ( Fig. 6 View FIG ). A previous molecular phylogeny based on two plastid (matK, ndhF) and five nuclear (ETS, ITS, KEA 1 introns 11 and 17, TEB exon 17) markers resolved P. megastyla (referred to as P. aff. brachybotrya ; Ledezma et al. 921, Sperling et al. 5873, 6161) in a strongly supported clade with P. supraglandulosa ( Cardinal-McTeague et al. 2019a;

summarized in Fig. 1 View FIG ). The ETS phylogeny of this study recovered P. megastyla in a poorly resolved polytomy within sect. Penninerviae, distinct from P. brevistyla ( Fig. 4 View FIG ). Both P. megastyla and P. brevistyla are vegetatively similar to P. brachybotrya , but the latter differs in its short massive globose stylar columns, 2–2.5 mm long ( Fig. 3C View FIG ), staminate flowers 1/node (compared to 1–3(4)/node), and primarily western Amazon distribution.

Sperling et al. 5873 (NY1461553) is unusual for having an aberrant pistillate flower with a slender-cylindrical stylar column and dilated apex. A younger pistillate flower on the sheet appears to have the typical oblong-obovoid stylar column.

Specimens Examined — Bolivia. — BENI: Prov. Iténez, Canton Mateguá, Campamento móvil Cerro Azul ubicado a 30 km de la Comunidad de Tiquin, [-13.816°, -62.761°], 738 m, 4 November 2006, Ledezma et al. 921 ( CAN, MO [accession 6057037, barcode MO-2115208 ]) . — SANTA CRUZ: Prov. Velasco, Los Fierros,la senda hacia la meseta adentro bosque alto,[-14.558°,-60.861°], 200 m, 20 August 1996, Jardim et al. 3336 ( MO [accession 04850338, barcode MO-1706758 ]) . Brazil. — MATO GROSSO: Mun. Vila Bela da Sant´ıssima Trindade, 41 km NNW of Pontes e Lacerda on BR364 to Vilhena, [-14.950°, -59.583°], 31 October 1985, Thomas et al. 4732 ( NY [barcode 010064912]). — PARÁ, Mun. Conceiçao~ do Araguaia, range of low hills ca. 20 km west of Redençao ~, near Sao ~ Jo~ ao and Troncamento Santa Teresa, approx. [-8.050°, -50.167°], 350–620 m, 12 February 1980, Plowman et al. 8741 ( NY [barcode 01461555]) ; Mun. Conceiç ~ ao do Araguaia, 100 km south of Redenç ~ ao on road (PA-150) to Barreiras dos Campos, Fazenda Inajapora ~ between Rio Inajazinho and Rio Inajá, approx. [-8.750°, -50.417°], 210 m, 19 February 1980, Plowman et al. 8908 ( NY01461551 ) ; Serra dos Carajás, 1–4 km along road from camp AZUL toward AMZA camp N-1, [-6.100°, -50.283°], 550–600 m, 28 May 1982, Sperling et al. 5873 ( MO [accession 4249342, barcode MO-2001412 ], NY [barcode 1461553]) ; Serra dos Carajás, 2–10 km southeast of ferry crossing on Rio Itacaiúnas , [-5.917°, -50.483°], ca. 225 m, 14 June 1982, Sperling et al. 6161 ( CAN, MO [accession 4247783, barcode MO-2001413 ], NY, US) .