There are several forms of African Dwarf Clawed Frogs available in the pet trade. They are mostly captive bred in Germany, Poland, Czech Republic, Indonesia, USA, Hong Kong and probably some more countries as well.

A large number of ADCFs in the pet trade are imported directly from Nigeria and Cameroon.
The taxonomy of Hymenochirus and Pseudhymenochirus is very confused. This means that it is very difficult to clearly identify the species and subspecies to which individual frogs belong. It follows therefore, that all references to their identity here should be viewed with caution.
It does seem however, that the majority of ADCFs in the Pet Trade belong to the Hymenchirus boettgeri group. In the USA ADCFs are often labelled as Hymenochirus curtipesbut in my opinion most of the photographs you are likely to see are of frogs belonging to the Hymenochirus boettgeri group.

Hymenochirus spec. 1 of Martin Truckenbrodt

Hymenochirus spec. 2 of Martin Truckenbrodt

Pseudhymenochirus merlini of Martin Truckenbrodt