UmbrellixPhaseolus ‘Mitla Black’ is probably not a tepary bean (tepar, t'pawi, Phaseolus acutifolius).
Abstract and methods
In the horticultural trade, the Mitla Black cultivar of Phaseolus sp. is sometimes labelled as a Phaseolus acutifolius, and I suspect any drought tolerance it exhibits serves as confirmation bias to the grower. I performed a DuckDuckGo search which turned up some studies not directly related, the USDA GRIN database, as well as non-scientific literature. I have come to the low-confidence conclusion that Phaseolus ‘Mitla Black’ is correctly called Phaseolus vulgaris ‘Mitla Black’, and is probably not a hybrid between acutifolius and vulgaris.
This work is a publication under the Evdonian ministerial-equivalent portfolio of the Ministry of Theoretical and Practical Agriculture. I did not receive funding of any kind, and I do not have a wage with the ministry.
This work is under construction!
Works used
https://heritagehobbyseed.com/index.php/product/mitla-black-semi-runner-bean-seeds/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4793507/
https://npgsweb.ars-grin.gov/gringlobal/search?q=pi%20550234
https://www.siskiyouseeds.com/products/beans-mitla-black-tepary