A new bizarre cicadomorph family in mid-Cretaceous Burmese amber (Hemiptera, Clypeata)

As the most diversified organismal group, insects evolved countless structural innovations, and some unique ones have vanished in their geological history. We herein report a new true hopper family Minlagerrontidae Chen, Szwedo and Wang fam. nov. with two new species (Minlagerron griphos Chen, Szwedo and Wang gen. et sp. nov. and Minlagerron onyxos Chen, Szwedo and Wang gen. et sp. nov.) in mid-Cretaceous Machin amber from northern Myanmar. The new family, tentatively attributed to Hylicelloidea (Clypeata), shares a series of plesiomorphies with ancient Clypeata, and also bears some extremely unusual or even grotesque morphological characteristics, never recorded in other Clypeata, Hemiptera, or even all fossil and living insects. This family possesses a greatly specialized head with tylus extremely broad, compound eyes produced, postclypeus almost transversely rectangular in the middle, with basal half having a deep longitudinal groove medially, and rostrum stout. The anterior part of minlagerrontid prothorax is sharply constricted, forming a unique 'neck' and 'shoulder' structures, and the prothoracic legs are also highly modified with strengthened femora with several lateral teeth and tibiae deviantly club-shaped. The female pygofer of the new family is completely wrapped by tergite VIII and its ovipositor is short and reduced. Additionally, minlagerrontids possess unique tegmina with C5 almost closed, surrounded by terminal branches of CuA, and thick venation reticular with multiple ambient veins ending at anterior margin and crossveins it and rp-mp diploid. The new highly specialized family erected herein suggests that in the Mesozoic, to reduce mutual competition, ancient Clypeata had diversified multi-dimensionally and so possibly evolved with high disparity to occupy a wide range of ecotypes. (C) 2019 Elsevier Ltd. All rights reserved.