Revising the systematic position of the extinct family Daohugoidae (basal Hymenoptera)

Two new species, <i>Daohugoa longa</i> Wang, Rasnitsyn &amp; Ren sp. nov. and <i>D. bella</i> Wang, Rasnitsyn &amp; Ren sp. nov. are described from the latest Middle Jurassic Jiulongshan Formation in north-eastern China. The new fossil evidence indicates that <i>Daohugoa</i> retains numerous plesiomorphies of basal Hymenoptera: an enlarged first flagellomere, complete xyelid-like venation, detached and folded laterotergites, and a laterally flattened sword-like ovipositor. Based on the combination of fossil and extant taxa, a phylogenetic analysis was conducted to clarify and ascertain the phylogenetic position of the extinct family Daohugoidae, which was originally classified in the superfamily Siricoidea. <i>Daohugoa</i> displays a contradictory array of characters. Its putative phylogenetic position within Hymenoptera is discussed in detail with reference to characters associated with the antenna, pronotum, wing venation, mesonotum and ovipositor. Based on the results from phylogenetic analysis and a combination of unique key features, we propose to include the group as a subfamily – Daohugoinae – within Xyelidae. These new findings increase our awareness of Mesozoic basal hymenopterans, and enhance our understanding of the evolution of morphological key characters for basal Hymenoptera. http://zoobank.org/urn:lsid:zoobank.org:pub:E6836213-132F-499A-9413-7C8971E2D5BF