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The steps towards an inconspicuous vein fusion documented in Stenosmylinae forewings (Neuroptera: Osmylidae)
- Cousin, Guillaume, Béthoux, Olivier
- Organisms, diversity, & evolution 2016 v.16 no.1 pp. 225-232
- Neuroptera, fossils, wings
- Based on respective numbers of branches in fore- and hind wing, and on the morphology of fossil species, it has been assumed that a fusion of the posterior branch of the posterior media (MP2) with the anterior cubitus (CuA) was acquired convergently in fore- and hind wings in several families of Neuroptera (Insecta), including the Osmylidae. The corresponding topographic homology conjectures (THCs) had to assume inconspicuous vein fusion, but without intermediate condition being reported. Based on inter-specific, intra-specific and intra-individual variations observed in forewings of a selection of Stenosmylinae species (Osmylidae), we herein document a complete transformation series ranging from the condition ‘MP2 and CuA approximating’ to ‘MP2 and CuA fully fused, without distinct origin of MP2’, with intermediate conditions in which the origin of MP2 has a cross-vein-like appearance. The relevance of series of conspecific specimens to investigate problematic THCs is emphasized.