Dental scales could occur in all scaled subfamilies of Entomobryidae (Collembola): new definition of Entomobryinae with description of a new genus and three new species

摘要

Body scales are fundamental in the classification of Entomobryidae at all taxonomical levels. Traditionally, scales on dens were considered to be absent in Entomobryinae, but present in other scaled subfamilies; however, this opinion was strongly challenged by recent morphological advances in tergal specialised chaetae (S-chaetae). A new genus, Lepidodens, is strikingly similar to the scaled Entomobryinae genus Willowsia in having pointed scales with relatively long ribs and 2, 2|1, 2, 2, 8, 3 tergal S-chaetae, but differs from it in having dental scales and a unique position of S-microchaetae on the first abdominal segment. Multilocus phylogeny and topology tests also support this view, the new genus clustering with Entomobryinae rather than Seirinae. Three new species, L. nigrofasciatus, L. similis and L. hainanicus, are described from South China. This study clearly undermines the traditional separation of Entomobryinae and Seirinae/Lepidocyrtinae, and demonstrates that dental scales could occur in all entomobryid subfamilies containing scaled taxa. In this new phylogenetic hypothesis, Entomobryinae has the greatest diversity in scale morphology and distribution among scaled collembolan groups, indicating multiple independent origins of scales.