Latin longus ‘long’ + Latin –cornis ‘-horned’. For the lower central spine, described by Bödeker as “strongly bent downwards in the shape of a horn and up to 25 mm long [versus 10 mm for the two upper central spines]”.
Bödeker received the plant under the provisional name Coryphantha ananas (Ananas comosus, pineapple), based on the local vernacular name biznaga piña (Spanish biznaga ‘globular cactus’ + Spanish piña ‘pineapple’). Compare the English name pineapple cactus for Coryphantha sulcata.
Maarten H.J. van der Meer (2022 Feb 25). Coryphantha longicornis. Dictionary of Cactus Names. Retrieved from https://www.cactusnames.org/coryphantha-longicornis