Lipochaeta and Melanthera (Asteraceae: Heliantheae subtribe Ecliptinae):: establishing their natural limits and a synopsis

We restrict the genus Lipochaeta to the allopolyploid species of the typical section. Lipochaeta s.str. is interpreted to be the result of an intergeneric hybridization between Melanthera and a presently unknown taxon, perhaps of the genus Wedelia. Lipochaeta is characterized, in addition to its allopolyploidy (n=26), by having both flavonols and flavones, disk corollas with 4 lobes, achenes tuberculate at maturity, the disk achenes flattened to slightly biconvex, and ray achenes ob-compressed. Lipochaeta sect. Aphanopappus and Wollastonia are here reduced to synonymy under Melanthera. We transfer 14 Hawaiian Lipochaeta and one New Caledonian species as well as the Asian Wedelia prostrata to Melanthera. These transfers, along with the species in Africa and North America, bring the number of species in the genus to 35. Melanthera is delimited by an abruptly narrowed to truncate and flattened top of the achene, (0-)1-15(-20) often unequal, ciliate or barbellate, caducous pappus bristles immediately surrounding the corolla, involucral bracts and receptacular paleae with many veins forming longitudinal striations, and n=15. The florets are 5-merous, the corollas are yellow or white, and rays are absent (in white-flowered species) or present and neutral or fertile. In dealing with species formerly placed in Lipochaeta, the Galapagos L. laricifolia is here transferred from the illegitimate generic name Macraea to Trigonopterum and the Brazilian L. goyazensis is transferred to Angelphytum. We maintain the earlier reduction of Echinocephalum under Melanthera and reduce all three taxa originally described in it to one, M. latifolia.