African arowana and arapima are more primitive form of their asian, australian and south american arowana cousins. They are all in sub-order: Osteoglossoidei which also includes the african butterfly fish. If you want to include all the order: Osteoglossiformes, which includes, Gymnarchidae (abas), Mormyridae (elephantfishes), Notopteridae (featherbacks/knifefishes). All are called bonytougues fishes. Unlike your comparison to the true gar species, Lepisosteiformes. Both hujeta gar and needlenose gars are not even closely related. Arapaimas, arowanas, abas, featherbacks, mormyrids and african butterfly fish are all related.