Stuardosatyrus Herrera & Etcheverry, 1965

Type species: Stuardosatyrus williamsianus (Butler, 1868) (Argyrophorus)

Diagnosis. Wing patterning somewhat resembles both Argyrophorus and Punargentus, but the pupillated M1-M2 ventral forewing ocellus sets it apart from Punargentus and, in addition to the lack of silver coloration, it is unlike Argyrophorus in the ventral hindwing postmedian band and the lack of yellow rings around the hindwing ocelli. Genitalic features further set it apart. The shape of the saccus, the shape of the aedeagus, and the general shape of the valvae as well as the deep serrations across the dorsal edge of the valvae indicate sufficient difference to warrant placement in a separate genus from Argyrophorus and Punargentus . Thus, Stuardosatyrus, named for Chilean dipterologist Carlos Stuardo Ortíz (1895–1962), remains a valid genus.

Remarks. Butler described a single, somewhat tattered female specimen that has the distinction of having been collected by Charles Darwin, though the original description is brief and entirely based on wing patterning. Heimlich (1963) followed williamsianus through the literature from its original placement in Argyrophorus, to Chionobas in Mabille (1884), to Satyrus in Staudinger (1899), to Cosmosatyrus in Elwes (1902), and demoted to a subspecies of Cosmosatyrus chiliensis in Hayward (1958) . Heimlich then returned williamsianus to its original position in Argyrophorus in his revision of the genus. Herrera & Etcheverry (1965) created a new genus, Stuardosatyrus, mainly on the basis of venation and differences in male genitalia. Heimlich (1972), followed by Pyrcz & Wojtusiak (2010), again returned williamsianus to a broadly-defined Argyrophorus, though with little evidence justifying this placement. However, Herrera & Pérez (1989) argued strongly, based on male and female genitalic dissections, that the Stuardosatyrus is distincs and valid.