**Acknowledgement**

A. Aragón (BUAP) helped with collection of specimens of *P. ravida* and G. Lugo (UAS) with collection of specimens of *P. opaca*. A special thanks to J. Valdez (COLPOS) and T. Laez (INECOL) with scanning electron microscope images. A.A.R.L. is grateful to INECOL for financial support during his postdoctoral stay.
