Another Recently Recognized Monotypic Genus is No Longer Monotypic: A Second Species of Pachycaulos (Gesneriaceae) from the Huancabamba Depression in Northern Peru

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A new species is described from the Huancabamba Pass, a relict montane forest in northwest Peru, near the southwestern border of Ecuador. Pachycaulos huancabambae J.L.Clark & Moonlight is a terrestrial or lithophytic herb with scandent stems that grows in dense mats of bryophytes. This is the second species of Pachycaulos and renders that taxon as non-monotypic. We discuss several other genera of Gesneriaceae that are also no longer monotypic because of recent exploratory research in tropical forests and increased taxon sampling from ongoing phylogenetic studies. A molecular phylogenetic analysis based on nrDNA ITS is presented that strongly supports the monophyly and sister-group relationship of P. huancabambae and P. nummularia. Based on IUCN guidelines, a preliminary conservation status is assigned as Critically Endangered (CR).