The following Mexican ticks labeled as Amblyomma triste Koch, 1844, were found in the Colección Nacional de Ácaros, Instituto de Biología, Universidad Nacional Autónoma de México: 4 males (M) and 4 females (F), ex cattle, Jun. 19, 1975, Las Pilas (28°49′N 102°00′W), Múzquiz, Coahuila; 1 M and 1 F, host, date and locality as above; 1 M, ex undetermined deer, Oct. 18, 1976, Yécora (28°22′N 108°56′W), Sonora. Both localities are in the Nearctic Zoogeographic Region. The ticks were confirmed as A. triste, thereby corroborating previous statements concerning the presence of this tick in Mexico. The current known distribution of A. triste includes the Neotropical and the Nearctic Zoogeographic Regions. Amblyomma triste is classified in the subgenus Anastosiella Santos Dias, 1963, whose members are difficult to differentiate in any stage. It is hoped that conventional and molecular taxonomic studies of Anastosiella species will help to clarify their range and phylogenetic relationships.