Neptune is a major demoness from the Solar System in the Milky Way Galaxy. She was first mentioned in Golem in the Gears.
Neptune has the Higgs boson particle field that generates mass and its ambiance is energy. It was introduced as male initially, but it was female in its next appearance. Its named is stylized as NEƛP/TƛUNE.
Novels: Golem in the Gears, Swell Foop, Board Stiff, Five Portraits
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.