How to differentiate between Clelia, Pseudoboa, Drepanoides?

[Jon Wedow]

I'm wondering about the small red snakes with the exact same colour pattern. And my question has nothing to do with range. I'm specifically thinking about parts of the Amazon where one may encounter all 3 genera.
The more I look at photos of head scalation the more confused I get .. there has to be something more, and I hope it is not counting ventral scales!

I'm intentionally holding back a photo until I hear some clear answers so that nobody guesses one or the other without an explanation

[Jeroen Speybroeck]

For Clelia vs. Drepanoides, it's not about ventral but about dorsal scales, if I remember well. You might want to check out some of the replies at the end of my Peru trip report thread here =>
viewtopic.php?f=2&t=17282

[Kfen]

You can tell by dorsal scale row counts
Clelia has 19 rows and a divided anal plate
Pseudoboa has 17 rows and an entire anal plate
Drepanoides has 15 rows and a divided anal plate.
(I'm not that good, I had to look up the numbers)

This snake gave us trouble until we counted. It was either a very large Pseudoboa, or a Clelia that retained juvie colors later than normal.
Turned out to be Pseudoboa


Here is a Drepanoides


Thanks for asking, it made my look at my photos from my trip again that I haven't in a couple of years.

[Jon Wedow]

Thanks everyone! i'll share a photo tonight. I hope I have enoigh photo evidence to make a possitive ID! i didn't realize there were so many possibilities until I returned home or I could have done a simple, on the spot, scale count ! But now I know, and hopefully others can reference this as well!

[Jeroen Speybroeck]

Thanks, Kfen, for the way more to-the-point reply!

[Gekkotan]

One more thing that should help, at least with southeastern brazilian Pseudoboa, they have unique subcaudals. This may work with amazonian too. Dont know about Drepanoides, but Clelia I am aware that have double subcaudals.

[Jon Wedow]

Based on some other photos I am fairly confident that this snake has 15 scales across the middle of the body ..... so Drepanoides?

Thanks for the help on this.

Jon