A new species of Tantilla is described from a single specimen obtained from Volcán Ceboruco, southern Nayarit, Mexico. The new species closely resembles other species of the Tantilla calamarina group. With the addition of the taxon described herein, the calamarina group now contains seven species, T. calamarina, Tantilla cascadae, Tantilla coronadoi, Tantilla deppei, Tantilla sertula, Tantilla vermiformis, and the new species described herein. Collectively, members of the group are distributed along the Pacific versant of Middle America in three disjunct regions: (1) from northern Sinaloa to Guerrero, including the Tres Marías Islands; (2) the Balsas Basin of Morelos, Puebla, Distrito Federal, and the State of Mexico; and (3) from El Salvador to northwestern Costa Rica. We provide a small list of specimens collected in the highlands of Nayarit, and report Lithobates psilonota, Ambystoma rosaceum, Elgaria kingi, Plestiodon lynxe and Rhadinaea hesperia for the first time from the state. We report the second specimen of T. sertula, known previously only from the holotype.