Explanation:

The WTO recognizes as least-developed countries (LDCs) those countries which have been designated as such by the United Nations. There are currently 48 least-developed countries on the UN list, 36 of which to date have become WTO members.
Eight more least-developed countries are negotiating to join the WTO. They are: Bhutan, Comoros, Equatorial Guinea, Ethiopia, Sao Tomé & Principe, Somalia, Sudan and Timor-Leste.

There are no WTO definitions of “developed” or “developing” countries. Developing countries in the WTO are designated on the basis of self-selection although this is not necessarily automatically accepted in all WTO bodies.