Prunus luxurians Pérez-Zab., Á. J. Pérez, Romol. & N. Albán, 2025

Prunus luxurians Pérez-Zab., Á. J. Pérez, Romol. & N. Albán sp. nov.

Figs 1 View Figure 1 , 2 View Figure 2 , 3 View Figure 3

Type.

Ecuador. El Oro: • Cantón Santa Rosa, Parroquia Torata, Buenaventura Reserve, Jocotoco Foundation , 03°33'54.7"S, 79°46'47.5"W, 1300–1400 m, 22 Dec 2021 (fl), Á. J. Pérez, P. Mena-Olmedo, A. de la Cruz, J. Zambrano & L. Aguilar 11743 (holotype: QCA; isotypes: LOJA, QCNE) GoogleMaps .

Diagnosis.

Prunus luxurians has a unique combination of leaves oblong lanceolate, cernuous in posture, around three times longer than wider, with prominent secondary and tertiary veins, secondary veins curved toward the margin and apparently eucamptodromous but becoming brochidodromous distally, base rounded to subcordate, floriferous shoots erect, densiflorous, less than 5 cm long, sepals with 2 marginal glands and flowers with turbinate hypanthium. Prunus integrifolia (Presl.) Walp. share with the new species the leaf shape and transverse posture, number of secondary veins, erect floriferous shoots and anthers of similar size; but, the new species has leaves shorter than 14 cm (vs. more than 15 cm.), chartaceous (vs. coriaceous), with conspicuous venation (vs. relatively obscure), glands submarginal and separated from the midrib (vs. attached to the midrib), turbinate hypanthium (vs. wide turbinate) and erect pedicels (vs. recurved) (Fig. 4 View Figure 4 ).

Description.

Tree up to 11 m tall; main trunk bark brown, grooved, with brown to light brown lenticels. Most recent growth units 2–2.6 mm diam. at base, with 8–9 leaves per unit, glabrous, angled, reddish brown in vivo; lenticels (0.2 –) 0.5–0.9 × 0.1–0.4 mm, elliptic to narrowly elliptic, slightly protuberant, density up to 32 per centimeter (at the base of last growth units); cataphylls 2.8–3 × 3.5–4.1 mm, trapezoidal, trilobed at the apex, glabrous. Leaves alternate, distichous on plagiotropic shoots, transversal posture cernuous when fresh; petioles 3.5–5.9 × 1–1.4 (– 1.8) mm long, flexuous, longitudinally grooved, glabrous; stipules paired, 1.3–1.5 mm at the base (scar), ca. 3.5 mm long, oblong falcate, apex acute, apparently deciduous when blades start expanding; leaf-blades (6.1 –) 10–13.65 × (2.9 –) 3.5–4.65 cm, around three times longer than wide, oblong-lanceolate, equilateral, chartaceous, conduplicate longitudinally, base rounded to subcordate, apex acute; margin entire to slightly repand; upper surface lustrous, impressed to slightly bulliform, glabrous; lower surface opaque, slightly rugose, glabrous; midrib 0.6–0.9 mm wide, slightly depressed above, prominent below, secondary vein framework apparently eucamptodromous but becoming brochidodromous distally, secondary veins 7–14 pairs, departing at 70–80 degrees from the midrib and progressively curving up to 30 degrees after the first quarter and almost parallel to the margin towards the end, slightly depressed above, raised below; intersecondaries 1–3 per intercostal area, following up the proximal trajectory of secondaries up to 20–30 % of their length; tertiary intercostal opposite percurrent sinuous, obtuse with respect to the midvein, epimedial tertiary alternate percurrent and perpendicular to midvein, distal course basiflexed, slightly depressed above, impressed below, exterior tertiary veins looped; quaternary and higher order veins inconspicuous; leaf glands 2, elliptic to circular, 0.5–1 × 0.5–1 mm, dark brown, sub-basal below the first pair of secondary veins, distanced (0.3 –) 1–1.2 (– 3.4) mm from the midrib and 0.2–0.9 mm from the margin. Floriferous shoots with a single axis, erect to suberect, present on the axils of all leaves and cataphylls of the current growth units, axis (17 –) 32–44.5 × 2.4–2.8 mm at the base and keeping a similar width until the middle, light green in vivo, glabrous, 14–27 flowered with groups of 3–4 flowers closer together; first flower at ca 8 mm from the base; cataphylls 1.6–3.7 × 1.2–4.1 mm, glabrous, trapezoidal, floral bracts not seen. Flowers pedicellate, pedicels 1.5–5.4 × 0.3–1.4 mm, straight, thickened at apex, white, glabrous; hypanthium 1.5–2.1 × 2–3.5 mm, turbinate, pale yellow, glabrous outside; sepals 0.7–1.2 × 0.7–1.5 mm, broadly triangular, margin entire, apex acute, glabrous outside and inside, slightly reflexed, with two marginal subapical glands that turn black when dry; petals 1.5–2.4 × 1.1–2 mm, widely obovate, 0.4–0.6 (– 0.8) mm wide at the basal claw, white, glabrous, apex rounded, margin entire, and slightly involute, venation with 4–6 lateral branches little conspicuous, eglandular; stamens 19–26, in two series, the outer series (3–3.2 mm long) longer than the inner one (1.5–2 mm long), glabrous, filaments 1.4–3.5 mm long, white, anthers 0.4–0.6 × 0.3–0.4 mm, basifixed with indorse dehiscence, elliptic-oblong, yellow; pistil 2–4.5 mm long, ovary 0.3–1.2 × 0.2–1.4 mm, glabrous, style 0.3–2.7 mm long, as long as or shorter than stamens, glabrous, stigma 0.5–1.0 mm wide, discoid-lobed. Fruit not seen.

Etymology.

We use the epithet luxurians to refer to the profuse blooming and outstanding beauty of this species at its flowering time that make it very conspicuous at the lower and mid-strata of the forest where it inhabits.

Distribution, habitat and ecology.

Known thus far only from the type locality in El Oro province, south-western Ecuador, a montane forest remnant at the Sambotambo-Birón area along the road to Cerro Pelado, between 1300–1600 m (Fig. 5 View Figure 5 ). According to the Ministerio del Ambiente del Ecuador (2013) the type locality lies in the Catamayo-Alamor evergreen piedmont forest (BsPn 02) that harbors high diversity and endemism ( Cerón et al. 1999; Myers et al. 2000) as a result of the Andes and Tumbesian region influence. In the Sambotambo-Birón area a total of five individuals of Prunus luxurians were observed growing on the borders of the forest remnants co-occurring with the following tree species: Guatteria microcarpa Ruiz & Pav. ( Annonaceae ), Dictyocaryum lamarckianum (Mart.) H. Wendl. , Wettinia kalbreyeri (R. Bernal) R. Bernal ( Arecaceae ), Guarea kunthiana A. Juss. ( Meliaceae ), Roupala montana Aubl. ( Proteaceae ) and the recently described Magnolia buenaventurensis Á. J. Pérez & E. Rea ( Magnoliaceae ) and Begonia jocotocoi Á. J. Pérez & Tebbitt ( Begoniaceae ) ( Pérez et al. 2023, 2024).

Phenology.

Flowering from October to January and probably fruiting in July to August (the latter according to testimonies of people living in the area).

Conservation status.

Known only from a single herbarium collection of a population of around five adults that we observed growing on the edges of the forest remnants in the Buenaventura Reserve, close to the road to Cerro Pelado in the Sambotambo-Birón area. Based on the available information, and according to the IUCN Red List Criteria and Guidelines ( IUCN Standards and Petitions Committee 2024), Prunus luxurians is preliminarily assessed as Critically Endangered (CR B 2 ab (iii )) because of its limited area of occupancy (AOO <5 km 2) and a single known population of around five individuals. Additionally, mining and farming activities currently threaten the forest remnants around the type locality. Priority reproduction studies and germination assays are needed for attempting ex-situ conservation of this promising ornamental species.