Tuesday, May 2, 2023

[Botany • 2023] Drypetes stevartii (Putranjivaceae)A Matter of Warts: A Taxonomic Treatment for Drypetes verrucosa and A New cauliflorous Species from Cameroon and Nigeria

Drypetes stevartii Sonké & Quintanar,  

in Quintanar, Sonké, Simo-Droissart, Barberá, Libalah et Harris, 2023. 

Background and aims – Specimens of a new tree species in the genus Drypetes (Putranjivaceae) distributed in Cameroon and eastern Nigeria, D. stevartii, were associated with D. verrucosa, another tree species endemic to Gabon, due to its warty fruits and to the overall morphological resemblances of both species.

Material and methods – The present study is based on the study of 20 gatherings of D. verrucosa and 26 gatherings of D. stevartii. Morphological observations on herbarium specimens belonging to the new species and D. verrucosa were carried out in order to describe them.

Key results – This treatment includes the detailed descriptions of these two species, the typification of their names, a comparative table summarizing their main morphological differences, an identification key, photographs of both, as well as information about their distribution, habitat, and phenology. Preliminary IUCN Red List assessments show that both D. verrucosa and D. stevartii are ‘Near Threatened’ species.

Keywords: Central Africa, conservation, dioecy, fruit dispersal, herbarium, isothiocyanates, IUCN Red List assessments, pollination, taxonomy

Drypetes stevartii Sonké & Quintanar.
A. Branchlet and leaves. B. Female inflorescence. C. Male inflorescence. D. Infructescences on the trunk. E. Infructescence with ripe fruits. F. Infructescence with immature fruits.
A, C from Sonké 7097; B from Sonké 7096; D from Sonké 7127 (type); E from Sonké 6975; F from Sonké 7094. Photographs A–F by Bonaventure Sonké, E by Murielle Simo-Droissart.

Drypetes stevartii Sonké & Quintanar, sp. nov.

Diagnosis: Haec species a Drypete verrucosa Pierre ex Hutch. stipulis 1.9–2.2 mm longis anguste triangularibus caducis, petiolis (2.6–)3–4.6(–5.1) mm longis confertim subtiliter rugosis, laminis foliorum (6.5–)7–11.1(–13.7) cm longis ad basim plerumque obliquis aliquando asymmetricis subter pubescentibus imprimis in nervis, inflorescentiis in truncum et ramorum principalium positis constantibus ex 1–7(–18) floribus, pedicello florum masculinorum (9.2–)14.7–20 mm longo, sepalis florum masculinorum 4.7–4.9 mm longis, disco florum masculinorum 3.1–3.3 mm diametro aliquantum exili sparsim pubescenti, staminibus 19–20, filamento 1.5–1.6 mm longo, anthera 2.2–2.4 mm longa anguste ellipsoidea sparsim pubescenti, pedicello florum femininorum 5.5–6.2 mm longo, sepalis florum femininorum 2.6–3.2 mm longis, disco florum femininorum 2.1–2.4 mm diametro glabro, fructibus (18–)20–29(–31) × 17–23(–25) mm late ovoideis, exocarpio 1–3 mm lato phymatodeo brunneo diluto luteolo tum aurantiacescenti vel rubescenti differt.

Distribution and chorology: Cameroon (Centre, East, Littoral, and West Regions) and eastern Nigeria (Adamawa) (Fig. 2). Lower Guinea subcentre of endemism (White 1979).

Etymology: According to the wishes of Bonaventure Sonké, the collector of the type specimen, we have named this new species after the botanist Tariq Stévart (b. 1974, Coordinator, West and Central Africa Program, Missouri Botanical Garden, Africa & Madagascar Department), in recognition of his helpful collaboration to our research on Drypetes and especially of his constant support to the second and third authors.

Alejandro Quintanar, Bonaventure Sonké, Murielle Simo-Droissart, Patricia Barberá, Moses Libalah and David J. Harris. 2023. A Matter of Warts: A Taxonomic Treatment for Drypetes verrucosa (Putranjivaceae, Malpighiales) and A New cauliflorous Species from Cameroon and Nigeria, D. stevartii. Plant Ecology and Evolution. 156(2): 160-173. DOI: 10.5091/plecevo.102004