The Custard Apples (Annonacaea) are a family of flowering trees and shrubs found throughout the tropics, some of which produce edible fruit. They are placed within the Magnoliales (Magnolias), generally thought to be one of the oldest groups of flowering plants. To date around 2450 species have been described. The genus Pseudephedranthus currently contains a single species from the Brazilian state of Amazonas and adjacent areas of Venezuela.
In a paper published in the journal Phytokeys on 21 September 2017, Roy Erkens of the Maastricht Science Programme at Maastricht University, and the Naturalis Biodiversity Center, Jessica Oosterhof of the Netherlands, and Lubbert Westra and Paul Maas, also of the Maastricht Science Programme at Maastricht University, describe a new species of Pseudephedranthus from Suriname, Guyana and the Brazilian state of Pará.
The new species is named Pseudephedranthus enigmaticus, presumably meaning 'enigmatic', though no explanation is given. While the species is newly described, Erkins et al. were able to find a number of specimens that they assign to it in different herbaria (plant collections) under a variety of names. The species forms trees up to 15 m in height in periodically inundated forests at altitudes of 100-600 m. It was observed to produce greenish white flowers in May to June, and black, ellipsoid fruit from June to September.
Drawing of Pseudephedranthus enigmaticus. (a) Flowering branch, (b) Flower in lateral view, (c) Staminate flower in longitudinal section, (d) Outer petal, (e) Inner petal, (f) Stamen, (g) Fruit, (h) Seed, small part of seed coat removed to show lamellate ruminations, (i) Cross section of monocarp and enclosed seed showing 4-parted rumination. Esmée Winkel in Erkins et al. (2017).
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