Grylloptera – a unique origin of the stridulatory file in katydids, crickets, and their kin (Archaeorthoptera)

Topographic homology conjectures (= THCs) of male forewing venation in extant ensiferan orthopterans (crickets, katydids, and their kin) and their close stem-relatives are re-evaluated, in order to test competing hypotheses on the origin(s) of the file (a row of teeth located on the ventral side of the forewing and used in stridulation). A new set of THCs (= STHC) is proposed, based on morphological data on the species †zeuneri Sharov, 1968, obscura Walker, 1869, monstrosa Uhler, 1864, †madygenicus Sharov, 1968: p. 181, grandidieri de Saussure, 1877: 287, bimaculatus de Geer, 1773, villosiceps Chopard, 1951, frontalis Walker, 1869, gryllotalpa Linnaeus, 1758, vicinus Scudder, 1869, and cantans Fuesslin, 1775. This STHC is compared to that proposed by Desutter-Grandcolas (2003) and is found to require a smaller amount of transformation to explain the observed morphologies. The favoured STHC implies that the stridulatory file is located along the same vein in all scrutinized taxa (viz. CuPb). Current phylogenetic hypotheses cannot rule out that the file was acquired once only. Furthermore, multiple losses explain the observed distribution more plausibly than multiple acquisitions of a complex structure. A new type of wing venation transformation is evidenced, referred to as tracheal un-capture. It involves a vein abandoning its usual course for another, and leaving a remnant of its previous course, in the form of a cross-vein-like structure (‘phantom vein’). The taxon Grylloptera is defined under cladotypic nomenclature, and is the lineage in which the character state ‘on ventral side, right and/or left forewings with a row of teeth (‘file’) located along CuPb’, as exhibited by viridissimus Linnaeus, 1758: p. 430 and campestris Linnaeus, 1758: p. 428, has been acquired. Type material is designated.