The anti-atoms are here for historical reason, they should no longer be used. See Category:Nuclide templates on how to create symbols for elements made of anti-matter.

Para-positronium Error no symbol defined Error no link defined
Ortho-positronium Error no symbol defined Error no link defined
Antihydrogen
H
Error no link defined
Antideuterium
D

D
Antitritium
T
Error no link defined
Antihelium
He
Error no link defined