Bitaeniata and diplotaenia

[Levin Tilghman]

These two species are remarkably similar in my opinion. How do you distinguish them, especially the females?

 

[MacZ]

I don't find them that similar to be honest. The finnage is completely different.

A. bitaeniata have a spiked mohawk-like dorsal with the first fin rays being elongated and ending almost filamentous. The caudal is lyre shaped. The females have a similar spiked dorsal, though shorter and the caudal is trapezoid with little to no markings.
In A. diplotaenia the dorsal starts off rounded with shot rays and never really shows height. The caudal is rounded spade shaped. In females the dorsal is similar and the caudal too, with dots and other markings.

And that's just what I can tell you from comparing 5 min after getting up without a coffee. Mike and Frank will be able to add a whole lot more and taxonomically more important diagnostics.

 

[Mike Wise]

This is fairly simple actually. A. bitaeniata females have a deeper body than female A. diplotaenia. The lateral band and abdominal band are always separate from each other.The lower abdominal band usually is not as pronounced as the upper lateral band and is also narrower. This varies to some extent depending on the species/population. A. diplotaenia females have a more slender body. They have NO second abdominal band. I know this sounds strange, but this species has only a single very broad abdominal band that has a lighter interior for most of its length. This make it appear to have 2 bands of equal width. Toward the tail (caudal peduncle) the dark parts of the band join together. Since there is only 1 band, the upper and lower sections are the same darkness.