Discovery of a new Mesozoic species of the ancient genus Lepicerus (Coleoptera: Myxophaga: Lepiceridae), with implications for the systematic placement of all previously described extinct ‘lepiceroids’

Abstract †Lepicerus mumia Jaloszynski & Yamamoto, sp. nov. is described based on a Cenomanian Myanmar amber inclusion. This is the third known and the best preserved fossil of ‘lepiceroid’ myxophagan beetles, making it possible to carry out a more detailed comparative study than previously published findings. Detailed analyses of diagnostic characters given by previous authors for †Haplochelus (†Haplochelidae) and †Lepichelus (= Lepiceroides ) (Lepiceridae) led to conclusions that some features might have been misinterpreted, others do not differ from those in Lepicerus , and the remaining morphological structures can be regarded as variable within one genus. Consequently, Haplochelus and Lepichelus are placed as junior synonyms of Lepicerus , and the synonymy between Haplochelidae and Lepiceridae, previously suggested by other authors, is maintained. Lepicerus mumia , although classified in the extant genus, shows an unusual, presumably ancestral myxophagan character state, a partly divided protarsus, with a distinctly demarcated, enlarged and curved tarsomere 1. The presence of a crust partly covering the body of L. mumia suggests a similar biology as that of two extant species that live near river banks among other semiaquatic arthropods.