The extinct order Caloneurodea (Insecta: Pterygota: Panorthoptera): wing venation, systematics and phylogenetic relationships
A new interpretation of the wing venation of the fossil insect order Caloneurodea is proposed. Complex fusions of veins are demonstrated, supporting the assignment of the Caloneurodea to the Panorthoptera, i.e. the order is closely related to the Orthoptera. A new diagnosis of the order is proposed. The following taxa are re-described after new interpretation, material or preparation, or are newly described: Caloneura dawsoni Brongniart, 1885 (= Boltonaloneura subtilis (Bolton, 1925) syn. nov .), Gigagramma carpenteri gen. and sp. nov .; Sthenarocera pachytyloides Brongniart, 1885, Pruvostiella lecomtei (Pruvost, 1919), Apsidoneura flexa Carpenter, 1943, Homaloptila similis (Meunier, 1911), Pleisiogramma medialis Carpenter, 1943 (= Pleisiogramma reducta Carpenter, 1943 syn. nov .), Paleuthygramma acuta Carpenter, 1943, Paleuthygramma sharovisp. nov ., Euthygramma parallelum Martynov, 1928 (= Euthygramma curvatum Martynov, 1931 syn. nov. ; = Paleuthygrammella aberrans (Martynov, 1938) syn. nov .), Anomalogramma parva Carpenter, 1943, Nanogramma gandi gen. and sp. nov ., and Ligogramma sinuosa gen. and sp. nov. The family Gelasopteridae Carpenter, 1976 is revised and its ordinal relationships are discussed. After the proposed phylogenetic frame, mutation(s) occurring in homeotic genes are expected to be responsible of the unusual wing morphology of the Caloneurodea, mixing fore- and hind-wing 'panorthopterid' features.