The genus Frigga includes 10 species, 3 of which are cited for Argentina (February 2017). It is very common for males of this genus to be confused with those of the genus Phiale. In males of the genus Phiale, the red dorsal spot of the opisthosoma (abdomen) borders the white part, while in the genus Frigga, it borders the black part (this is only noticeable in dorsal or lateral view). This distinction can only be applied to specimens from the Argentine provinces of Buenos Aires, Entre Ríos, Santa Fe, Córdoba, San Luis, Mendoza, and La Pampa, primarily because in Misiones, Uruguay, or Brazil, there are species that "break" the abdominal color rule (such as Phiale gratiosa).
Frigga coronigera is found in Brazil and in Argentina only in Misiones. Frigga finitima is found in Bolivia and in Argentina only in Salta and Jujuy. Frigga quintensis is found in the central and northern parts of Argentina, southern Brazil, and possibly in Uruguay and Paraguay.
I believe the most appropriate approach would be to classify specimens from northern Argentina (Misiones, Chaco, Formosa, Salta, and Jujuy) and bordering countries as Frigga sp., and those from other Argentine provinces as Frigga quintensis.

Comment by: Luciano Peralta, updated by Lucas Rubio (07/01/2019).