Abstract. A new genus and species of fossil wood wasp is described
and figured from mid-Cretaceous Kachin amber, representing the first
occurrence of the family Xiphydriidae in the fossil record. Paraxiphydria resinata gen. et
sp. nov. exhibits typical apomorphies of the family including a generally
cylindrical body, elongate neck and dome-shaped head. Nonetheless, owing to
a unique combination of traits including features hitherto unknown among
species of the family, the genus is classified within a separate subfamily,
Paraxiphydriinae subfam. nov. A key is presented to the
suprageneric groups of Xiphydriidae. The newly described species is the
first fossil xiphydriid wood wasp, extends the occurrence of Xiphydriidae
into the mid-Cretaceous and adds to the known diversity of features in the
family. Lastly, the simplification of wing venation and hypotheses of
host-plant affiliations of early xiphydriids are discussed. We evaluate
pollen associated with the wasp, assign it to the genus Cycadopites and conclude
that an affiliation to the Cycadales is most likely. Article and nomenclatural acts are registered in ZooBank (http://zoobank.org/, last access: 15 December 2021), with the following life science identifier (LSID) (reference): urn:lsid:zoobank.org:pub:DA80920E-E94B-4A8E-A817-077FA7BD7D69.
Burrowing bugs are distinctive, beetle-like insects of the pentatomoid family Cydnidae, noteworthy for their morphological specializations for digging and a hemiedaphic life history. However, less is known about their biological significance and the early origin of soil dwelling. Direct fossil evidence illuminating the evolutionary history of soil dwelling in cydnids is extremely rare. In this study, we report four new species of the burrowing bug subfamily Amnestinae from mid-Cretaceous Burmese amber, including two exhibiting specialized bulldozing and digging morphological traits on the anterior of the head and forelegs. Associated morphological features and phylogenetic placement indicate that Acanthamnestus represents the earliest unequivocal soil-dwelling cydnids and pushes back the geological record of hemiedaphic true bugs to 99 Ma. Environmental evidence, the distribution of host plants, and the fossils provide a new window for understanding the early origin of soil habits in Amnestinae and may be linked to the appearance of Moraceae.
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