The ammonite Hybonoticeras authariformis new species [M] is erected from the lower Tithonian of Mexico, adding a new example of endemism for the genus Hybonoticeras in records from epicontinental areas. The newly described species is the first evidence of unequivocal lowermost Tithonian macroconchiate hybonoticeratines reported from the Mexico-Caribbean area. Precise biostratigraphic control based on bed-by-bed sampling is first reported for the combined record of macroconchiate Hybonoticeras Breistroffer, 1947 with Mazapilites Burckhardt, 1919 in Mexico, indicating an early but not earliest Tithonian age. A preliminary revision of the type material of species assigned to the genus Mazapilites points to an inconclusive understanding of both intraspecies diversity and the real meaning of the nominal species formulated by Burckhardt, thus revealing defective knowledge about precise biostratigraphy at both the genus and species levels. Published hybonoticeratines and mazapilitines from Mexico and Cuba are revisited to update precise interpretation of their systematics, biostratigraphy, and correlation potential, and to investigate their combined occurrence. Previous information about Cuban hybonoticeratines and mazapilitines is too limited to be conclusively interpreted; their combined record cannot be demonstrated in Cuba. Special relevance is given to a potential occurrence of Mazapilites in uppermost Kimmeridgian horizons in Cuba. The obtained results update the biostratigraphic meaning and systematic interpretation of the investigated ammonites, and signal topics for future research of interest in their paleobiological and palebiogeographic interpretation.

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