Gastrocopta pentodon are commonly mistaken with Gastrocopta tappaniana.  However Gastrocopta tappaniana are found in wet environments and near water.  They look identically alike.  Occasionally they will be found interacting with each other, if the Gastrocopta pentodon is in a wetter environment than normal and the Gastrocopta tappaniana is in a drier than normal area.   

Gastrocopta Pentodon                                                         Gastrocopta tappaniana

Photo on Left side of Gastrocopta pentodon.  Photo on Right side Gastrocopta tappaniana.