Pinus yecorensis -Yécora Pine
Found in 1994 near the town of Yécora, Sonora, Pinus yecorensis turned to be a characteristic hard pine growing (at the type locality) at around 1800 m. Subsequently it was also found 230 km south of Yécora in Chihuahua near the Sonora border, as reported by Rick Fencl.
Based on search for additional information, it seems that other data are also available, so the Yécora Pine may be rather common in southeastern Sonora and adjacent areas, mainly along the mountain ranges of Sierra Madre Occidental.
The Arizona State University Vascular Plant Herbarium provides a map with collection data – a very useful reference but perhaps needing confirmation especially in case of specimens coming from lower elevations (as in one case 900 m, nr. Tepoca). As briefly discussed in Conifers Around the World, page 1012, var. sinaloensis is a southern variety occurring at lower elevations (1100-1300 m) also confirmed by specimens and photographs of DAP team associate Jeff Bisbee (Nevada).
This one is a somewhat smaller tree with umbrella-shaped crown and smaller cones. - Hopefully more and more explorations will provide sufficient data so that the ranges of these pines can be precisely established.