to turn out or end up with dark skin (see Molina)
yapaltia. ni. (pret. oniyapaltix.) pararse moreno. Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 31v. col. 1. Thanks to Joe Campbell for providing the transcription.