Silverstoneia flotator vs. Allobates talamancae in Costa Rica
Costa Rica has 7 species of Poison Frogs. Most are very easy to separate based on appearance and/or distribution.
But 2, Silverstoneia flotator and Allobates talamancae, which are actually in completely different families are often confused.
I spent some time doing research on distinguishing these frogs, one great reference is The Dendrobatid Frogs of Central America (1968) by Jay M. Savage*.
While amazingly superficially similar, Silverstoneia flotator has an "oblique lateral stripe" from the groin to the eye that is actually lacking in Allobates talamancae. In Allobates talamancae there is a dorsolateral stripe which looks very similar but it originates above the leg (not in the groin and thus not oblique/diagonal across the body) and extends passed the eye. I've found the best way to tell if you're looking at a oblique lateral stripe (Silverstoneia flotator) or a dorsolateral stripe (Allobates talamancae) is to look at the end that hits the leg/groin. If it hits the groin (oblique lateral stripe) there will usually be some black side of the body color above the stripe visible before you get to the lighter brown dorsal top of the frog. If it hits the leg above the groin (dorsolateral stripe) the stripe itself will be the border between the black side of the body color and the lighter brown dorsal top of the frog.
Also male Allobates talamancae have gray/black throats/bellies which are white in Silverstoneia flotator. And Allobates talamancae are a bit larger (snout to urostyle lengths of 17–24 mm vs 14.4–18 mm in Silverstoneia flotator). Once you go south into Panama, there are other species in the mix (Silverstoneia nubicola, Colostethus pratti, Colostethus latinasus, Colostethus inguinalis, Colostethus panamansis) that make things a bit more complicated. I might update this post with them at some point.
Alot of poison frogs mimic one another to take advantage of learned poison avoidance by predators. I wonder if thats whats going on here, because for being in different families, Silverstoneia flotator and Allobates talamancae sure do look amazingly similar!
Thanks to @wasatch_hunter for posting the awesome photos I made use of here
*The names have changed a bit since the Savage paper, here's a mapping to the current taxonomy
Savage -> current
Dendrobates auratus -> Dendrobates auratus
Dendrobates granuliferus -> Oophaga granulifera (genus change)
Dendrobates pumillo -> Oophaga pumilio (genus change)
Dendrobates speciousus -> Oophaga speciosa (genus change, also extinct)
Dendrobates minutus -> Andinobates minutus (genus change)
Phylobates lugubris -> Phyllobates vittatus/Phyllobates lugubris/Andinobates claudiae (split)
Colostethus inguinalis -> Colostethus inguinalis/Colostethus panamansis (split)
Colostethus latinasus -> Colostethus latinasus
Colostethus pratti -> Colostethus pratti
Colostethus nubicola -> Silverstoneia nubicola/Silverstoneia flotator (split and genus change)
Colostethus talamancae -> Allobates talamancae (genus change)
Savage doesn't include these species, I'm not sure why, maybe not discovered yet?
Andinobates geminisae
Andinobates fulguritus
Oophaga vicentei