In Spanish, felino is a male gender word, and la is a female gender article. Technically, the correct writing of Sendelina's surname is del Felino, or just Felino.
However, this surname might refer to Sendelina's ancestors. De la Felino can mean "he/she who belongs to the Felino woman". This surname may have originated as a nickname for the child of a woman surnamed "Felino". Therefore, a son of hers would be called, for example, "José el de la Felino" (José, the son of that Felino woman), and through the generations, the nickname would have evolved to an official surname, "de la Felino".
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