Disentangling the identity of Pterocaulon rugosum and P. alopecuroides (Asteraceae, Inuleae), with a description of a new species
24 November 2017
Monge, Marcelo; Volet, Danilo; Anderberg, Arne; Semir, JoãoTaxonomic studies in Brazilian Inuleae (Asteraceae) have revealed that the name Pterocaulon rugosum (Cass.) Malme has been misapplied because its type belongs to the same species that is currently recognized as Pterocaulon alopecuroides (Lam.) DC. Additionally, several works supposed that Pterocaulon rugosum (Cass.) Malme was based on Conyza rugosa Vahl, which is illegitimate, because it is predated by Conyza rugosa Dryand. So, Conyza rugosa Vahl is the replaced synonym and Chlaenobolus rugosus Cass. was a new name, the basionym of Pterocaulon rugosum (Cass.) Malme. The species hitherto referred to P. rugosum is a separate species that requires a new name and is described here as Pterocaulon cabrerae. It is characterized by broad leaves with a whitish adaxial surface, and capitula grouped in terminal glomerules. It occurs in savannas and temperate grasslands in Brazil, Colombia, and Paraguay. Affinities are discussed and an identification key for similar species is provided. Additionally, four lectotypifications, three subsequent lectotypifications, one neotype, and one new synonym, were made to provide nomenclatural stability to Pterocaulon alopecuroides.