Friday, September 29, 2023

[Botany • 2020] Memecylon afroschismaticum (Melastomataceae: Olisbeoideae) • A New Species endemic to the East African Rift region of Rwanda, Burundi and western Tanzania


Memecylon afroschismaticum R.D.Stone,

 in Stone, 2020. 
Drawn by Sandie Burrows.

Abstract
Background – A new species of Memecylon (Melastomataceae–Olisbeoideae) from Rwanda, Burundi and western Tanzania is described in connection with preparing the family treatment for the Flore d’Afrique centrale.

Methods – Standard herbarium practices were applied.

Key results – Memecylon afroschismaticum R.D.Stone is described and illustrated. This new species is remarkable for being endemic to forests of the East African Rift region avoided by all but a few other species of African Memecylon. A close relationship with M. flavovirens Baker (type of M. sect. Obtusifolia Engl.) is suggested by its corolla being narrowly conical-acute in bud and anther connectives with dorsal oil-gland and acute posterior extremity. However, its elliptic-ovate and distinctly acuminate leaves resemble those of M. myrianthum Gilg (of M. sect. Polyanthema Engl.) and M. verruculosum Brenan (of M. sect. Buxifolia R.D.Stone). The known location in western Tanzania is formally protected within the Mahale Mountains National Park, but the subpopulations in Rwanda and Burundi are unprotected and presumably threatened by high human population density and subsistence agriculture. The estimated area of occupancy is also quite small (12 km2). Memecylon afroschismaticum is thus provisionally assessed as Endangered [EN B1ab(iii)+B2ab(iii)] in accordance with IUCN criteria.

Keywords: Burundi, East African Rift, Melastomataceae, Memecylon afroschismaticum, new species, plant taxonomy, Rwanda, Tanzania

Memecylon afroschismaticum.
A . Flowering branch. B . Leaf. C . Section of branchlet showing axillary cyme. D . Floral bud. E . Anther dissected from oral bud, side view (left), top view (right). F . Fruit.
A from Bridson 287 (BR); B–E from Runyinya 935 (K); F from Harley 9597 (K). 
Drawn by Sandie Burrows.

Memecylon afroschismaticum R.D.Stone, sp. nov.

Etymology – The epithet afroschismaticum is a neuter adjective meaning “of the East African Rift region.


 Robert Douglas Stone. 2023. Memecylon afroschismaticum sp. nov. (Melastomataceae–Olisbeoideae) endemic to the East African Rift region of Rwanda, Burundi and western Tanzania. Plant Ecology and Evolution. 153(1); 160-166. DOI:10.5091/plecevo.2020.1657