A synoptic revision ofPohliella(Podostemaceae) with notes onAulea, CipoiaandSaxicolella

Abstract

ABSTRACTSaxicolellaEngl., an African genus of the waterfall specialist plant family Podostemaceae, was shown to be polyphyletic as currently delimited. One clade, sampled from species in Ghana, is sister to AmericanCeratolacis(Tul.)Wedd.,PodostemumMichx. and all Old World Podostemoideae (podostemoids). The second clade, sampled from Cameroonian material, was embedded within the major clade of African podostemoids. In this paper the generic nomenclature applied toSaxicolellasensu lato (Saxicolella, PohliellaEngl., AuleaLebrun & Stork nom. inval.), is reviewed and the morphological support for the two clades and their correct generic names is determined.Pohliellais shown to be the correct name for the first clade (based onPohliella laciniataEngl., Cameroon) and a synoptic treatment of its three published species is given, one of which is extinct, and two are threatened. However, a fourth, unpublished species exists. The new combinationsPohliella submersa(J.B.Hall) Cheek andPohliella amicorum(J.B. Hall) Cheek are made for the two published Ghanaian species. The recently described New World genusCipoiaC.T. Philbrick, Novelo & Irgang is revealed as being morphologically identical toPohliella, but in view of the geographical disjunction, confirmation from molecular evidence is awaited before its two species are also transferred toPohliella. The correct name for the second clade, embedded in African podostemoids, isSaxicolella(sensu stricto), now with two known species,Saxicolella nanaEngl. (type ofSaxicolella,Cameroon) andSaxicolella flabellata(G.Taylor) C. Cusset (Nigeria).