Discovering Karima (Euphorbiaceae), a New Crotonoid Genus from West Tropical Africa Long Hidden within Croton.

Gill Challen,Ricarda Riina,Martin Cheek,Patricia Barberá,Hannah Banks,Nico Cellinese,Aiah Lebbie

doi:10.1371/journal.pone.0152110

Gill Challen, Ricarda Riina + Show 5 more

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https://doi.org/10.1371/journal.pone.0152110

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Abstract

Croton scarciesii (Euphorbiaceae-Crotonoideae), a rheophytic shrub from West Africa, is shown to have been misplaced in Croton for 120 years, having none of the diagnostic characters of that genus, but rather a set of characters present in no known genus of the family. Pollen analysis shows that the new genus Karima belongs to the inaperturate crotonoid group. Analysis of a concatenated molecular dataset combining trnL-F and rbcL sequences positioned Karima as sister to Neoholstia from south eastern tropical Africa in a well-supported clade comprised of genera of subtribes Grosserineae and Neoboutonieae of the inaperturate crotonoid genera. Several morphological characters support the relationship of Karima with Neoholstia, yet separation is merited by numerous characters usually associated with generic rank in Euphorbiaceae. Quantitative ecological data and a conservation assessment supplement illustrations and descriptions of the taxon.

Highlights

The environmental impact assessment of the Bumbuna-Yiben Hydroelectric Dam project in Sierra Leone which was led by Xander van der Burgt of the Royal Botanic Gardens, Kew, with colleagues from the National Herbarium of Sierra Leone provided numerous plant collections [1]
It was eventually matched at K with material named as Croton scarciesii Scott-Elliot, including both syntypes, these authors noted that the main morphological characters of Croton scarciesii disagree with most typical Croton L. features and matched no known genus
Field studies of Karima at the Taia River reported in S2 Appendix were conducted by the National Herbarium of Sierra Leone, which has the national statutory responsibility for study of the vegetation and plant species of Sierra Leone and requires no individual permits in order to conduct field surveys

Summary

Introduction

The environmental impact assessment of the Bumbuna-Yiben Hydroelectric Dam project in Sierra Leone which was led by Xander van der Burgt of the Royal Botanic Gardens, Kew, with colleagues from the National Herbarium of Sierra Leone provided numerous plant collections [1]. Among the resultant herbarium specimens, one (Momoh 94) proved of great interest. The presence of a single ovule in each carpel excludes the material from Phyllanthaceae [2, 3], as the presence of petals and absence of white exudate excludes the material from Euphorbiaceae–Euphorbioideae [2, 3]. It was eventually matched at K with material named as Croton scarciesii Scott-Elliot, including both syntypes, these authors noted that the main morphological characters of Croton scarciesii disagree with most typical Croton L. features and matched no known genus.

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