What is the key visual difference between megastoma and ipiranga

[anewbie]

Wetspot has a few megastoma for sale (wc but unclear if red specs or yellow specs) but i was comparing pictures to my ipiranga and other then the ipiranga having blue specs the form, shape and colouring of the fishes look very similar. In my naive way i would almost thing the ipirgana is a blue spec megastoma.

So i was wondering if someone with actual knowledge about the fishes taxonomy might know in more detail how the two species differ....

 

[Frank Hättich]

On the few pictures of different A. sp. Ipiranga specimens I know, I can't see any relevevant differences to A. megastoma.