Research Article |
Corresponding author: Juan Ernesto Guevara Andino ( jguevara@fieldmuseum.org ) Academic editor: Hugo de Boer
© 2020 Juan Ernesto Guevara Andino, Diana Fernandez-Fernandez.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Guevara Andino JE, Fernandez-Fernandez D (2020) A new rare and endemic species of Sloanea (Elaeocarpaceae) from the Chocó region of Ecuador. PhytoKeys 160: 131-139. https://doi.org/10.3897/phytokeys.160.54993
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A new species collected in the lowland forests of the Chocó region of Ecuador, Sloanea cayapensis, is described and illustrated and its morphological similarities with other species of Sloanea are discussed.
Chocó, Ecuador, endemic, lowland humid forest, Sloanea
The genus Sloanea L. is the second largest within the family Elaeocarpaceae and comprises approximately 200 species in the tropics and more than 120 species in the Neotropics (
The most recent taxonomic study of Sloanea in Ecuador revealed that 25–30 species of the genus occur in the country (
We describe a new species of Sloanea from the Ecuadorian Chocó region, based on an analysis of morphological characters from material deposited in four Ecuadorian herbaria: the Herbario de la Pontificia Universidad Católica del Ecuador (
Sloanea cayapensis resembles S. grandiflora Smith and S. fragrans Rusby, the most morphologically similar taxa, but can be differentiated from them by having short petioles (2–7.5 cm), obovate-spatulate leaves, 6–8 free sepals, shorter thick and acute-obtuse anthers (1.5–2 mm), densely hirsute filaments and styles and by having capsules with large, flexible, curled bristles (2.8–6 cm).
Ecuador. Esmeraldas: Borbón-Río Cayapas, 78°50'W, 1°5'S, 10 m elev., 3 May 2003, Jaime Jaramillo, A. Sola, S. Yandun 24200 (holotype [2 sheets]: QCA7007914! (fl, fr); QCA7007917!; isotypes QCA7007915!,QCA7007916! (fl), QCA204513!).
Medium-sized trees up to 15–18 m tall. Trunk striated, bark rough, brownish. Branchlets glabrous, quadrangular and covered by ovoid, cream-coloured lenticels. Leaves alternate; petioles 2–7.5 cm long, semi-terete, striated, shortly pubescent, thickened at the insertion with the blade; blades (18.8–)42–52(–61.8) cm long, (9.5–)17–26(–32) wide, coriaceous obovate-spatulate, attenuate-subcordate or rounded at base, obtuse-retuse at apex, the margins entire, slightly revolute; foliaceous stipules persistent at the top of the individual branchlets, 3.9–13 cm long, 2.1–3.9 cm wide, elliptical with acuminate apex, the margin entire or shallowly sinuate; primary vein prominent on the adaxial surface, very prominent and angular on the abaxial surface, secondary venation eucamptodromous, 11–20 secondary veins, prominent on the abaxial surface and ascendant (angle > 45°), flat on the adaxial surface, tertiary veins prominent on the abaxial surface, slightly flat on the adaxial surface. Inflorescence axillary, racemose; peduncles 2–6 cm long; rachis 5–18.5 cm long, slightly pubescent, deeply striated and quadrangular; pedicels 1–7 cm, stout, shortly pubescent, finely striate and quadrangular, pedicels, 1–1.5 cm long, navicular bracts at the base of individual pedicels, 4–4.5 mm long, dense appressed pubescence on both abaxial and adaxial surfaces, apex acute, commonly deciduous. Flowers with the receptacle large, expanded; sepals 6–8, free, 3–5 mm long, 2.5–3 mm wide, greenish coloured, ovate, apex acute-acuminate, margins entire, slightly involute, yellow on the outer surface, not covering the reproductive organs before anthesis. Stamens 5–6 mm long, yellow with orange anthers; filaments 3–3.5 mm long, densely hirsute, striated and angulate; anthers 1.5–2 mm long, densely hirsute, thick, the connective thin on the abaxial surface of the anther sacs, extended as an acute or obtuse awn, very short, up to 0.5 mm long; anther sacs not opening widely along entire length. Ovary 2–4 mm long, 1.5–2.7 wide, with four locules, 4-angled, ovoid, densely hirsute; placentation axillary; style to 8 mm long, densely hirsute at the base, becoming sparsely hirsute towards the apex. Fruits globose capsules 1.2–2.5 cm long, 1–2 cm wide, rounded, opening by 4 rigid valves; bristles 2.8–6 cm long, curled, contorted and flexible, laterally flattened, densely hirsute at the base, more sparse and appressed pubescence towards the apex, easily detached. Seeds not studied.
Paratypes. Ecuador: Esmeraldas: La Chiquita, bosque secundario, 45 m elev., Jaime Jaramillo 24422 (
Sloanea cayapensis is a medium-sized tree only known from two localities on high alluvial terraces along the Cayapas River in the Lowland Evergreen Forests of Equatorial Chocó (
From the Spanish word Cayapa, with reference to the Chachi indigenous group that inhabits a great portion of the evergreen lowland forests of the Equatorial Chocó in Ecuador. The word Chachi means ‘pure’ in the Cha’palaachi language. The species name was first proposed by the late Ecuadorian botanist J. Jaramillo as a written annotation on herbarium specimens, but was never validly published.
Sloanea cayapensis may be catalogued as Endangered (EN) following
Based on our description, Sloanea cayapensis is morphologically similar to S. grandiflora and S. fragrans, both members of the subgenus Sloanea. The new species can be readily distinguished from S. fragrans by having longer (3–3.5 mm vs. 1.5–2 mm long) and densely hirsute angle-striated filaments (vs. cylindrical puberulent filaments). It also differs from S. fragrans by having shorter anthers (1.5–2 mm vs. 2–3 mm long), acute or obtuse awn-shaped (vs. lanceolate) anthers densely hirsute (vs. glabrous to sub-glabrous), lanceolate stipules with entire margins (vs. navicular with remarkable irregular serrate margins) and shorter petioles (2–7.5 cm vs. 5.5–20(–25) cm long) (see Table
Diagnostic characters for Sloanea cayapensis and its closest relatives, as well as their geographical distribution in the Neotropics: Western Amazon (WA), Central Amazon (CA), Chocó region (Chocó), Central America (CAm) and the Guiana Shield (GS).
Characters | Sloanea cayapensis | Sloanea grandiflora | Sloanea fragrans |
---|---|---|---|
Leaf size | (18.8–)42–52(–61.8) long, (9.5–)17–26(–32) cm wide | 21–43.5 cm long, 15–25.5 cm wide | 45–65 cm long, 21–29.5 cm wide |
Leaf shape | Obovate-spatulate | Elliptic to elliptic-bovate | Obovate |
Leaf margins | Entire to shallowly sinuate | Irregularly dentate | Irregularly undulate |
Stipules | Lanceolate with entire margins | navicular with irregular serrate margins | navicular with finely dentate margins |
Stamens | 5–6 mm long | 7–9 mm long | 4–8 mm long |
Filaments | 3–3.5 mm long densely hirsute angle-striated | 2–4 mm long angled or laterally flattened | 1.5–2 mm long cylindrical puberulent |
Anthers | 1.5–2 mm long, thick and obtuse | 3–4 mm long, linear-lanceolate | 2–3 mm long, lanceolate |
Ovary | Ovoid, 2–4 mm long, 1.5–2.7 mm wide | Ovoid, 4 mm long, 2.5 mm wide | Globose, 3 mm long, 3 mm wide |
Style | Densely hirsute in its entire length up to 8 mm long | Pubescent at the base glabrous above, 7–9 mm long | Pubsecent in its entire length, 5–10 mm long |
Capsule | Globose densely covered by curled flexible spines | Ellipsoidal covered by stramineous flexible curled spines | Globose densely covered by short spines |
Elevation | 0–500 m | 0–1500 m | 0–1100 m |
Geographic distribution | Chocó | WA, CA, GS and CAm | WA and CAm |
Sloanea cayapensis is distinguished from S. grandiflora in having a densely hirsute style (vs. glabrous style at the apex and slightly pubescent at the base), thin connective (vs. very wide connective between the anthers sacs on the abaxial surface), thick and obtuse anthers (vs. linear-lanceolate) and an ovoid and densely hirsute ovary with 4 locules (vs. pubescent ovary with 4–6 locules). It also differs from S. grandiflora in having lanceolate stipules (vs. navicular stipules with finely dentate margins), shorter pedicels (4–11 mm vs. 7–25 mm) and strongly ascendant numerous secondary veins (11–20 vs. 13–15 slightly ascendant secondary veins).
We thank the staff at the herbaria