Systematic revision of the genus Isostigma Less.(Asteraceae, Coreopsideae)

摘要

Isostigma Less. (Asteraceae, Coreopsideae) is a South Ameri-can genus, distributed in Argentina, Brazil, Bolivia, Paraguay,and Uruguay. This genus has 2 subgenus (Isostigma Less. andMicrotrichon Guad. Peter) including 11 species (Isostigma acaule(Baker) Chodat, Isostigma brasiliense (Gardner) B. D. Jacks.,Isostigma cordobense Cabrera, Isostigma dissitifolium Baker,Isostigma herzogii Hassl., Isostigma hoffmannii Kuntze, Iso-stigma molfinianum Sherff, Isostigma peucedanifolium (Spreng.)Less., Isostigma scorzonerifolium (Baker) Sherff, Isostigma sim-plicifolium Less. and Isostigma sparsifolium Guad. Peter) and6 varieties. Here are described the new subgenus Microtrichonand the taxon Isostigma peucedanifolium var. strictum Guad.Peter. Three new status and combinations are made: Isostigmapeucedanifolium var. crithmifolium (Less.) Guad. Peter, Isostigmapeucedanifolium var. speciosum (Less.) Guad. Peter andIsostigma simplicifolium var. riedelii (Baker) Guad. Peter. Threelectotypes are designated for the names Isostigma hoffmannii,Isostigma peucedanifolium var. crithmifolium and Isostigmascorzonerifolium. Two neotypes are designated for the namesIsostigma cordobense and Isostigma simplicifolium Less. var.simplicifolium. One name (Isostigma megapotamicum (Spreng.)Sherff) is excluded. Distribution maps and identification keysare provided.