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Which L # would this be?

In the entire batch, 13 of them, there appears to be 2 species, 12 of one and 1 of the other.

I can't get a good pic of the odd one out.

These are Chaetostoma cf. thomsoni (L187b).

Because most streams harbor 2-3 spp. of Chaetostoma it is common to find two spp. in the same shipment. Yours came from Colombia. On an interesting note, a bunch of this same spp. showed up in the aquarium trade here in Mexico this week. I bought all six I could find (between 2 pet stores) but they all appear to be the same spp.
-Shane