Aztec Dancer looks almost identical to California Dancer A. agrioides, and their ranges overlap considerably throughout California. There are a few spots in extreme northeastern California where only Aztec occurs (so far) and a few locales in the southeast where only California Dancer is known (so far), but they can occur together throughout the California foothills. Usually, though, one species is most abundant. In Monterey County, that common species is California Dancer. There are, however, specimens of Aztec Dancer in adjacent San Benito County.

On 25 Aug 2007, Don Roberson and Paul Johnson were looking for odes along a stretch of the San Lorenzo River, on private land east of King City. Here the river forms the boundary between Monterey and San Benito counties (all photos here are from the MTY side). While Paul worked downstream, Don decided to try to sort through the hundreds of Argia dancers then ovipositing on flotsam in the river. He netted a random half-dozen (all A. agrioides) and then focused on photography. He noticed that there were a few "pale blue" males among the many bright blue male California Dancers; this photo (below) shows the two types together (pale one to the left, darker blue one to the right).

Once one has narrowed down the California/Aztec Dancers to just the ones with relatively unmarked second segments, identification is made in-hand or in close-up photography by looking at the appendages (on males) or the mesostigmal plates (on females). I can only illustrate the identification of males here; for females, see figure 12 on p. 52 of Manolis (2003).

For males, although there are other differences in appendage details, the easiest to see is the relative width of the two torus, compared to the gap between them. One needs to get overhead with a clean dorsal view to do this comparison. The differences are illustrated in the photos by yellow and red lines, but these lines are set off the tip of the appendages while, in fact, one needs to be comparing width at the base of the cerci, just at the end of the blue on the final segment. On California Dancer (below left) the gap between the tori (red) is about the same width as either torus (yellow). On Aztec Dancer (below right) the gap between the tori (red) is only about half as wide as either torus (yellow).