The genus Arachis contains about 70 species, including A. hypogaea (cultivated peanut) and its two probable progenitors, A. duranensis and A. ipaensis. These species and a few other important relatives (used as sources of disease resistance and in mapping experiments) are described in the links below.

Arachis duranensis
A progenitor of cultivated peanut, with a sequenced genome
Arachis ipaensis
A progenitor of cultivated peanut, with a sequenced genome
Arachis magna
A wild peanut relative found mainly in Bolivia
Arachis hypogaea
Cultivated peanut
Arachis monticola
A wild peanut relative, used in some studies of cultivated peanut
Arachis stenosperma
A wild peanut relative, used in some studies of cultivated peanut

More about Arachis ... A short review on 'Arachis duranensis, Arachis ipaensis, and the Origins of Cultivated Peanut' (PDF)