Phaseolus esquincensis Freytag (2002: 170) [clade A; sect. Xanthotricha A. Delgado].

TYPE: GF Freytag 78-Mex-75 (HOLOTYPE: US-3168870; ISOTYPES: BR, F-2107873, GH, K-262842, MICH-1210017, NA-27952) .

Apparently known only from the type material, this member of the Xanthotricha has been validated elsewhere (Delgado-Salinas et al. 2006). While the other members of this section have variously shaped tuberous taproots, this species seems to have a fibrous root; the terminal leaflets are hastately lobed, markedly towards the base (infrequent trait).