Gea
(after Levi 1983): Gea differs from Argiope by having the posterior eyes about equally spaced; those of Argiope have the posterior medians farther from the laterals than the posterior medians from each other. Gea differs from both Argiope and Neogea by having the anterior head region bearing the posterior median eyes swollen. The epigynum is usually weakly sclerotized, the openings sometimes hidden and appearing more elaborate and specialized than those of most Argiope species. The male palpus has a longer median apophysis, a more elaborate conductor, again appearing more specialized than the palpus of Argiope species, although I expect that some species are intermediate between the two genera. All Gea species are relatively small, females 5 to 9 mm total length.
Molecular data appears to support that Gea is a junior synonym of Argiope (Scharff et al. 2020).
Publications
Levi HW (1983): The orb-weaver genera Argiope, Gea, and Neogea from the western Pacific region (Araneae: Araneidae, Argiopinae).. Bulletin of the Museum of Comparative Zoology. 150: 247 - 338
Scharff N, Coddington JA, Blackledge TA, Agnarsson I, Framenau VW, Szúts T, Hayashi C & Dimitrov D (2020): Phylogeny of the orb-weaving spider family Araneidae (Araneae: Araneoidea). Cladistics. 36: 1 - 21