title: Specialized adaptations for springtail predation in Mesozoic beetles.
abstract: Insects exhibit a variety of morphological specializations specific to particular behaviors, and these permit the reconstruction of palaeobiological traits. Despite the critical importance of predator-prey strategies in insect evolution, the appearance of particular aspects of predation are often difficult to determine from the fossil record of hexapods. Here we report the discovery of highly specialized, mid-Cretaceous ant-like stone beetles (Staphylinidae: Scydmaeninae) displaying morphological modifications unknown among living scydmaenids and associated with predation on springtails (Collembola), a widespread and abundant group of significantly greater geological age. Cascomastigus monstrabilis gen. et sp. nov. exhibits an extremely large body size, elongate clubbed maxillary palpi, toothed mandibles, and more importantly, slender and highly modified antennae that functioned as an antennal setal trap. Such an antennal modification is analogous to that of the modern ground beetle genus Loricera (Carabidae: Loricerinae), a group possessing a specialized antennal setal trap exclusively for the capture of springtails. The presence of an identical antennal setal trap in C. monstrabilis demonstrates a unique and dramatic form of obligate predation among the late Mesozoic insects.
authors.affiliation: Department of Biology, College of Life and Environmental Sciences, Shanghai Normal University, Shanghai, 200234, P. R. China.
authors.forename: Zi-Wei
authors.initials: ZW
authors.lastname: Yin
authors.affiliation: Key Laboratory of Economic Stratigraphy and Palaeogeography, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing, 210008, P. R. China. cycai@nigpas.ac.cn.
authors.forename: Chen-Yang
authors.initials: CY
authors.lastname: Cai
authors.affiliation: State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing, 210008, P. R. China.
authors.forename: Di-Ying
authors.initials: DY
authors.lastname: Huang
authors.affiliation: Department of Biology, College of Life and Environmental Sciences, Shanghai Normal University, Shanghai, 200234, P. R. China.
authors.forename: Li-Zhen
authors.initials: LZ
authors.lastname: Li
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D057506:Arthropod Antennae / Q000033:anatomy & histology; D049628:Body Size; D005580:Fossils / Q000033:anatomy & histology*; D000074746:Neoptera / Q000033:anatomy & histology* / Q000145:classification / Q000502:physiology; D010802:Phylogeny; D011235:Predatory Behavior; D014070:Tooth / Q000033:anatomy & histology