A newly discovered adult beetle †Lepiceratus ankylosaurus gen. & sp. nov. (mid-Cretaceous Myanmar amber) is the first extinct member of the suborder Myxophaga to reveal fine morphological structures, studied by synchrotron microtomography. A comprehensive phylogenetic analysis places it as a stem group in the extant relict family Lepiceridae. The fossil (along with previously known taxa) demonstrates that lepicerids with seven and five antennomeres co-existed during mid-Cretaceous, and only forms with extremely reduced, pentamerous antennae survived till present. The hitherto known fossil record of the enigmatic myxophagan beetles and phylogenetic reconstructions demonstrate that the reduction of antennomeres (i.e. antennal anarthrogenesis) from the ancestral 11 to seven took place as early as the Triassic, when the ancestral lineage of Myxophaga split into the ‘lepicerid lineage’ and an ancestor of all remaining families. Furthermore, the anarthrogenesis in the ‘Lepicerus lineage’ had been completed by the mid-Cretaceous. As all remaining morphological structures that define extant Lepicerus had differentiated by then, the extreme reduction of antennae to merely five antennomeres was the last major morphological transformation in their evolution. Morphological adaptations to protect body appendages (presumably against predators) also remained unchanged since the mid-Cretaceous, indicating a similar environmental pressures during this nearly 100 Ma-long period of lepicerid evolution.

https://zoobank.org:pub:28DCD51D-90EA-4516-810E-3B898DE5A729

新发现的成年甲虫† Lepiceratus甲龙gen。＆sp。十一月 （白垩纪缅甸中期的缅甸琥珀）是Myxophaga亚目的第一个灭绝成员，该亚目揭示了精细的形态结构，这是通过同步加速显微镜研究的。全面的系统发育分析将其作为现存的残pic科Lepiceridae的茎类。化石（以及以前已知的分类单元）表明，白垩纪中期有七个和五个天线虫的类鳞翅目动物共存，只有到极短的五角触角的形式才得以生存。迄今已知的神秘粘虫甲虫和系统发育重建的化石记录表明，早在三叠纪，就将触角蚁从祖先的11个减少到了7个，当Myxophaga的祖先血统分裂为“ lepicerid血统”和所有其余家庭的祖先时。此外，“Lepicerus世系已在白垩纪中期完成。到那时，所有定义现存Lepicerus的其余形态结构都已分化，触角极度减少到仅5个触角虫是其进化的最后主要形态学转变。自白垩纪中期以来，用于保护肢体附件（可能抵御捕食者）的形态学适应性也保持不变，这表明在近100 Ma的长类象鼻虫进化期间，环境压力相似。

https://zoobank.org:pub:28DCD51D-90EA-4516-810E-3B898DE5A729