Phaseolus montanus Brandegee (1893: 130) [possibly clade B; sect. Acutifolii Freytag].

TYPE: TS Brandegee 162 (LECTOTYPE: UC-82396) .

When Townshend Stith Brandegee reported about the flora of the Cape region of Baja California in 1893, he included his collection numbers, namely a “162. Phaseolus montanus,” but he did not make explicit that it was a new species nor that it was the type. That plant in the Brandegee Herbarium now at Berkeley, although labelled as type, was considered as synonym of P. acutifolius var. tenuifolius A. Gray (Delgado-Salinas 1985 p. 178), a treatment endorsed by George Freytag who did not see it. Comparing this plant with the holotype of P. parvifolius (US-3168875), the following synonymy can be indicated:

Phaseolus montanus Brandegee (based on TS Brandegee 162 as lectotype UC-82396 and published in: Proc. Calif. Acad. Sci. ser. 2, 3:130. 1893)

= Phaseolus parvifolius Freytag (based on GF Freytag & J Sullivan 81-13 as holotype US-3168875; ISOTYPES: BR, EAP n.v., MEXU n.v., MO, and published in: Sida Bot.Misc.23:32.2002).

This taxon has consistently been evidenced as closely related to P.acutifolius (Fig. 1), but with differences that warrant the species status (Florez-Ramos et al. 2003; Muñoz et al. 2006; Gujaria-Verma et al. 2016).

Specimens: U.S.A. Arizona: RA Darrow 2261 (ARIZ-15237). MEXICO. Sonora: P Tenorio-Lezama 10254 (TEX-272992). Chihuahua: CH Muller 3443 (LL-273004). Baja California Sur: R Domínguez 313 (MEXU-431892). Sinaloa: A Delgado-Salinas 1042 (BM). Nayarit: OTéllez-Valdés 12306 (MEXU-490786). Jalisco: M Lavin 5072 (CHAPA). Colima: AC Sanders 11455 (RSA-554182). Michoacán: VW Steinmann 3860 (IEB-169341). Guerrero: DG Debouck 2354 (MICH-1180063). Oaxaca: M Sousa-Sánchez 9420 (NCU-531247). Chiapas: GF Freytag 78-Mex-77 (F-2107874). GUATEMALA. Jalapa: DG Debouck 2434 (MICH-1180058).