Gochnatia (Asteraceae, Mutisieae) and the Gochnatia Complex: Taxonomic Implications from Morphology

Abstract

Gochnatia is one of the largest genera of the tribe Mutisieae (Asteraceae) and has been traditionally characterized by its homogamous capitula with isomorphic corollas. A morphological study of Gochnatia and associated genera, i.e., Actinoseris, Chucoa, Cnicothamnus, Cyclolepis, Hyalis, lanthopappus, Nouelia, Pleiotaxis, and Wunderlichia, was carried out to evaluate the circumscription of Cochnatia and its sections, and the affinities of this complex of genera. The characters studied involve habit, leaf features (consistency, pubescence type, shape, margin, and venation), types of capitulescence, involucre features (shape, size, phyllary series, pubescence, and shape), paleae, floret features (morphology, sex, number, color of corolla, anthers, style shapes, achenial pubescence, and pappus). Analysis of these features revealed: (1) although Cochnatia is highly variable in most of the characters studied, it can be defined by this suite of features: isomorphic to subdimorphic corollas, apiculate anther appendages, and smooth style branches; (2) sections of Gochnatia needed to be re-evaluated. As result of this, two sections, i.e., sect. Discoseris and sect. Pentaphorus, are confirmed; two sections are proposed, i.e., sect. Glomerata sect. nov. and sect. Rotundifolia sect. nov.; three sections are redefined, i.e., sect. Hedraiophyllum, sect. Leucomeris, and sect. Gochnatia, while sect. Anastraphioides is formally published; and (3) the combination of apiculate anther appendages and smooth style branches is unique to Actinoseris, Cnicothamnns, Cyclolepis, Gochnatia, Hyalis, lanthopappus, and Nouelia within the Mutisieae. This group of genera is recognized here as the Gochnatia complex, with Cochnatia as the basal genus of this complex. Chucoa, Pleiotaxis, and Wunderlichia do not belong to the Gochnatia complex.