Relationships of Cretaceous Ripiphoridae (Coleoptera) based on larval morphology, with evidence for the same reproduction timing and chosen microhabitat for oviposition

Five specimens of primary larvae of Ripiphoridae (Insecta: Coleoptera) are reported from one piece of Cretaceous Kachin amber. They represent two morphotypes: one conicocephalate and one belonging to the tribe Ripidiini (represented by four specimens). The conicocephalate morphotype is compared with similar larvae known from Kachin, Taimyr and Manitoba Cretaceous amber, and the larvae of Ripidiini are compared with their Cretaceous, Eocene and extant relatives. Phylogenetic analyses were performed to establish a working hypothesis about possible relationships of both lineages. The results, which conform with a recent molecular phylo­geny, indicate that the larvae described here belong to Ripidiini or are closely related, respectively. To allow taxonomic and systematic work with conicocephalate larvae from Kachin amber, a collective group name †“ Ripilarva ” nov. is proposed here to accommodate these immature stages. Both species of †“ Ripilarva ” nov. from Kachin amber are described: †“ R. ” parabolica sp. nov. and †“ R. ” kachinensis sp. nov. Syninclusion of †“ Ripilarva ” kachinensis sp. nov. and four larvae of a species of Ripidiini indicate that females of both ripiphorids chose the same time and microhabitat for oviposition in the Kachin Cretaceous forest. The results are further verified by the use of UV-photography, as the different larval morphotypes occurred in the same resin flow. The presence of larvae of Ripidiini in clusters contrary to the solitary occurrence of †“ Ripilarva ” nov. in Cretaceous amber of Russia, Canada, USA, and Myanmar is interpreted as a possible result of different oviposition strategies, with different numbers of eggs deposited at one spot. Graphical abstract