A morphological study and cladistic analysis of Sinningia and associated genera with particular reference to Lembocarpus, Lietzia, Paliavana, and Vanhouttea

Sinningia and two other tuberous South American genera of Gesneriaceae, Lembocarpus and Lietzia, were transferred to tribe Gloxinieae by Wiehler (1983) with the note that further study may place the latter two genera within the circumscription of Sinningia. A morphological study of the species of these three genera, as well as two nontuberous genera, Paliavana and Vanhouttea, was undertaken. The objectives were to elucidate the relationships. among these genera and critically examine their circumscriptions. Lembocarpus was determined not to share any synapomorphies with the other genera examined and was therefore excluded from Gloxinieae and referred to Episcieae near Rhoogeton. Cladistic analysis of the cultivated species of the other genera revealed that the present division of Sinningia into two subgenera, Sinningia and Rechsteineria, cannot be supported. Four well-defined clades can be recognized in Sinningia, but the relationships of these.four clades to each other remain uncertain. The species of Lietzia share several synapomorphies with one of these clades, and their transfer to Sinningia is recommended. The species of Paliavana and Vanhouttea form a monophyletic group and may be members of another of the clades of Sinningia, but this placement cannot be considered conclusive. If further study supports this relationship of Paliavana and Vanhouttea to Sinningia, it is recommended that Sinningia be divided into four genera, corresponding to the four clades discovered by cladistic analysis, as such an arrangement would allow a clearer definition of the genera.