The Linnaean taxon Titanoptera is a distinctive Triassic insect order the origin of which is uncertain. Forewing venation patterns of the Permian Linnaean subfamily Tcholmanvissiinae (Orthoptera) and of the Titanoptera are re-investigated. The comparative analysis supports the view that the morphology of the latter group is derived from that of the former. As a consequence, the order Titanoptera is to be included within the subfamily Tcholmanvissiinae. A cladotypic taxonomy is developed in order to avoid the confusion inherent to taxonomic rearrangements associated with rank-based taxonomy. The following hierarchy is proposed: (Archaeorthoptera nom. Béthoux & Nel, 2002a, dis.-typ.n. (Pantcholmanvissiida nom. n., dis. Béthoux & Nel, 2002b, typ.n. (Tcholmanvissiidae nom. Zalessky, 1934, dis. Sharov, 1968, typ.n. (Tcholmantitanopterida nom.-dis.-typ.n. (Tcholmanvissiella nom. Gorochov, 1987, dis.-typ.n. (Titanopterida nom.-dis.-typ.n. (Gigatitanidae nom. Sharov, 1968, dis. -typ.n.))))))). This fi rst application of cladotypic taxonomy unveiled several practical aspects of this system. A system governing the adaptation of pre-occupied taxon names is developed based on various cases of character state formulations; the issue of the occurrence of Linnaean suffi xes and of the preservation of Linnaean binominals within a cladotypic taxonomy are discussed; the capacity to handle the ancestor ‘species’ vs. apomorphy-less sister-species issue by the various nomenclatural systems is discussed.

Pterygota, Archaeorthoptera, Orthoptera, Titanoptera, Titanopterida, cladotypic taxonomy, adaptation, priority, ancestor species.