Limnomma, a new genus of Ommatidae from the Middle Jurassic Daohugou beds (Coleoptera, Archostemata)

Abstract

The relictual archostematan beetle family Ommatidae attained high diversity during the Mesozoic. Despite their once high taxonomic diversity and morphological disparity, many Mesozoic ommatid taxa remain poorly understood, partly due to limited preservation. Here we report an exceptionally well-preserved fossil, which we describe as a new ommatid genus and species, Limnomma daohugouensegen. et sp. nov., from the mid-Jurassic Daohugou Lagerstätte in Northeast China. The new genus can be most easily distinguished from other ommatids by the presence of a circular non-tuberculate region on ventrite 5. The new taxon is discussed in relation to the classification of the Mesozoic genera Brochocoleus and Burmocoleus.