What are the four main types of coffee trees?

Ethelsa species Ethelsa species is a variety discovered only in 1904, native to the Charlie River Valley in Africa, small fruit, high yield per plant, especially a drought-resistant variety. The product has strong flavor and slightly bitter taste. It is less cultivated in Liberia. Liberia is a large-grain species. It is native to Liberia in Africa and a few countries such as Malaysia. It's been cultivated longer