Sylvia is a female sylph from Xanth. She was introduced in Man from Mundania.
Sylvia is the widow of Sylvester and mother of Sylvanie.
Sylvia is the widow of Sylvester forced by goblins to lure other people to their lair under threat of the death to her child.
Human men and women will not have a species in their entries. Also, if the surname of the character is the character's species, it was dropped.
If the character is a child, it will be in the description. The child will more than likely be an adult by this time in the Xanth series.
Many species are single gender, so their entries will not mention it. The species are Fury, Muse, basilisk, cenmaid, cenmare, cockatrice, dryad, maenad, sand witch, sandman, and woodwife. Harpies and nymphs are usually female, and fauns are usually male; but there have been a few exceptions that are noted.
In some instances, I have made educated guesses on gender, species, and some birth years.