Research paper Galls and gall makers on plant leaves from the lower Miocene (Burdigalian) of the Czech Republic: Systematic and palaeoecological implications Stanislav Knor a, ⁎, Marcela Skuhravá b , Torsten Wappler c , Jakub Prokop a, ⁎ a Charles University in Prague, Faculty of Science, Department of Zoology, Viničná 7, CZ-128 44, Praha 2, Czech Republic b Bítovská 1227, CZ-140 00 Praha 4, Czech Republic c Steinmann Institute for Geology, Mineralogy and Palaeontology, Division Palaeontology, University of Bonn, Nussallee 8, D-53115 Bonn, Germany abstract article info Article history: Received 20 April 2012 Received in revised form 2 October 2012 Accepted 4 October 2012 Available online 3 November 2012 Keywords: Plant–arthropod associations Fossil galls Acari Insecta Neogene Most Basin 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 com- prises 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). © 2012 Elsevier B.V. All rights reserved. 1. Introduction Galls are remarkable structures, which may occur on roots, stems, leaves, flower buds and flowers and on fruits of various plants. Most are cause by parasitic insects, but the formation of galls can also be induced by viruses, bacteria, fungi, nematodes, and mites (Price et al., 1987; Stone and Schönrogge, 2003). The ability of organisms to induce galls on plants has evolved independently many times during the evolution of insects as well as of other groups, with over 13,000 described species with this habit (e.g., Shorthouse and Rohfritsch, 1992; Williams, 1994; Crespi et al., 1997; Raman et al., 2005a). Galls are believed to provide the inducer with enhanced nutrition, a favorable microclimate and, in some cases, protection from natural enemies (Stone and Schönrogge, 2003). Insect galls are thus an extended pheno- type of their inducers — with the gall exposed to selection pressures related to predation and host resistance (Dawkins, 1982; Stone and Schönrogge, 2003). About 80% of the insect galls are found on leaves, but the first documented occurrence in the fossil record is on plant stems (Labandeira, 1998). Nearly three thousand extant gall-causing and associated organisms are known from Central and Northern Europe (Buhr, 1964–1965). They belong to various groups of organisms: about one third to bacteria and fungi, two-thirds to animals. Three groups of animals are the species richest causers of galls on various plants: (i) the gall midges (Cecidomyiidae, Diptera) with about 600 species; (ii) eriophyid mites (Eriophyoidea, Acarina) with about 350 species and (iii) aphids (Aphidoidea, Hemiptera) with about 370 species. Since that time many new species of gall-causing organisms have been discovered and de- scribed and the number of these organisms is at present much higher. Due to prevailing subtropical climatic conditions in Neogene of Central Europe it can be supposed that there was higher insect diversity includ- ing probably some other gall inducing taxa like thrips (Thysanoptera). In this paper we describe the induced fossil plant galls from the lower Miocene of the Most Basin in the northern Bohemia and imple- ment a quantitative and taxonomic analysis of gall occurrences. These galls are two- or three-dimensional impressions, preserved as remains or traces found on various plant organs, most frequently on leaves. On the basis of the gall similarities in the form, size and their position on the leaves of the fossil host plants it was possible to identify their taxo- nomical group to at least generic level and to ascribe their relationships to gall-inducing species that currently cause morphologically similar galls on related host plant species. It is likely that some causers of Neogene galls are tightly related to their recent relatives, since the Review of Palaeobotany and Palynology 188 (2013) 38–51 ⁎ Corresponding authors: Tel.: +420 221951837; fax: +420 221951841. E-mail addresses: knor@natur.cuni.cz (S. Knor), skuhrava@quick.cz (M. Skuhravá), twappler@uni-bonn.de (T. Wappler), jprokop@natur.cuni.cz (J. Prokop). 0034-6667/$ – see front matter © 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.revpalbo.2012.10.001 Contents lists available at SciVerse ScienceDirect Review of Palaeobotany and Palynology journal homepage: www.elsevier.com/locate/revpalbo