Ophiogomphus (Ophionurus) australis spec. nov. from the Gulf coast of Louisiana, with larval and adult keys to American Ophiogomphus (Anisoptera: Gomphidae)

The new sp. is described from adult and larval material (holotype <J, allotype 9: Tangipahoa R., 5 km E of Kentwood, Tangipahoa Parish, Lousiana, USA) and its affinities discussed. Calogomphus subg.n. (type sp.: Erpetogomphus eutainia Calv.) and Erpetocyclops subg.n. (type sp.: Erpetogomphus ophibolus Calv.) are introduced, and keys to the American onychogomphine genera and subgenera are presented, inch species keys to adult and larval American Ophiogompus.