A contribution to the knowledge of leaf-mining Phyllocnistis Zeller, 1848 associated with Baccharis (Asteraceae), with description of two new species from Peru (Lepidoptera: Gracillariidae).

We provide new information on Neotropical Phyllocnistis Zeller (Gracillariidae) associated with Baccharis (Asteraceae) in the Andes region. Two new species are described, P. canta Cerdea Farfn, n. sp. and P. elongata Cerdea Farfn, n. sp., from the western slopes of the Andes of Peru between 2,000 and 3,000 m elevation, both associated with Baccharis latifolia (R.P.) Pers. The type locality of P. baccharidis Hering is confirmed; immature stages were found at 1,300 m feeding on Baccharis tucumanensis Hook. Arn. in Quebrada las Higueras (Tucumn, Argentina). Four new locality records for P. furcata Vargas Cerdea are provided, extending its distribution by 450 km to the north of the type locality.

Atacamaptilia ambrosiavora gen. et sp. nov. (Lepidoptera: Gracillariidae), a leaf miner of Ambrosia cumanensis (Asteraceae) in the Atacama Desert.

Adult and immature stages of Atacamaptilia ambrosiavora Vargas Espinoza-Donoso gen. et sp. nov. (Lepidoptera: Gracillariidae: Acrocercopinae) from the Atacama Desert of northern Chile are described and illustrated. The Neotropical Atacamaptilia Vargas Espinoza-Donoso gen. nov. resembles the Old World genera Melanocercops Kumata Kuroko, 1988 and Phodoryctis Kumata Kuroko, 1988 in wing venation. However, differences in genitalia morphology enable the recognition of Atacamaptilia Vargas Espinoza-Donoso gen. nov. as a different genus. COI sequences support this delimitation, since it is not closely phylogenetically related to these genera. A divergence of 18% (Kimura 2-parameter model) of A. ambrosiavora Vargas Espinoza-Donoso gen. et sp. nov. to its nearest neighbor Leucospilapteryx omissella (Stainton, 1848) was found. The larvae of A. ambrosiavora Vargas Espinoza-Donoso gen. et sp. nov. mine leaves of Ambrosia cumanensis Kunth (Asteraceae).