Galls and gall makers on plant leaves from the lower Miocene (Burdigalian) of the Czech Republic: Systematic and palaeoecological implications

A detailed study of more than 4000 plant macrofossils from the lower Miocene of the Most Basin (localities Bílina Mine and Břešťany) in northern Bohemia has been made in order to implement quantitative and taxonomic analyses of gall occurrences. Fourteen distinct arthropods were identified as possible causers of fossil galls. Similarities in the form, size and position on the host-plant leaves allowed identifications at least to the generic level and to discuss their relationships to extant gall-inducing species that cause morphologically similar galls on related host-plant species. The fossil galls were induced by members belonging to the following insect and mite families: Psyllidae (Hemiptera), Cecidomyiidae (Diptera), Cynipidae (Hymenoptera) and Eriophyidae (Acari). Galls on Taxodium induced by gall midges of the genus Taxodiomyia (Diptera: Cecidomyiidae) are recorded for the first time. All here described galls are the first records of fossil galls from the Neogene of the Central Europe and complement the view plant–insect interactions during the lower Miocene. The Bílina Mine collection comprises material from several fossiliferous layers representing also different ecosystem types. The presence of elevated gall frequency in the Lake Clayey Horizon (LCH) accompanied by the lower diversity of the other damage types implies colder and drier habitat with unevenly distributed rainfall in comparison with Delta Sandy Horizon (DSH).

► Miocene horizons were compared with respect to arthropod galls on plant leaves.
► Results of quantitative analysis prove significant differences of galling level.
► Their frequency and diversity are influenced by environmental changes.
► Relationships between gallers and host plants show long evolutionary stasis.