A hotspot of subterranean Collembola in ferruginous rock caves and Mesovoid Shallow Substratum is revealed by the analysis of pseudocryptic diversity. The diversity is accessed by detailed description of chaetotaxy and slight variation in morphology of 11 new species of Trogolaphysa Mills, 1938 (Collembola, Paronellidae, Paronellinae) and the 50 previously recorded species of springtails from caves, using optical and electronic microscopy. When combined with recent subterranean surveys, our results show an important reservoir of cave diversity in the Mesovoid Shallow Substratum. Contrastingly the conservation policy for subterranean fauna in metallogenic areas in Brazil prioritizes the caves instead the cave species, which may be extremely detrimental to the fauna in the shallow subterranean habitats not accessible to humans.

Herein, eyeless Pseudosinella species from Brazilian caves are reviewed, including the description of 23 new species, new records plus additional notes on the descriptions of P. ambigua Zeppelini, Brito, and Lima and of P. guanhaensis Zeppelini, Brito, and Lima. We also provide an identification key to 27 eyeless species recorded from Brazil. To organize the 26 Brazilian eyeless taxa analyzed in this work, we organize them in apparently artificial groups: 11 species have one larger tooth on the unguiculus outer lamella (petterseni group); one presents unguiculus outer lamella smooth or serrated (never with a larger tooth), with 9 held prelabral chaetae undivided and the last 6 held prelabral chaetae bifurcated. The Brazilian species of eyeless Pseudosinella herein described present a remarkably conservate dorsal chaetotaxy; therefore, the main diagnostic characters are related to other features like prelabral, labral, and ventral head chaetotaxy and empodial complex morphology. In addition, our study suggests that Brazilian caves possibly shelter a great diversity of Pseudosinella taxa, several of them potentially cave dependent.

The description of a new species, Cyphoderus caetetus sp. nov., led to comparisons among Paronellidae (Cyphoderinae and Paronellinae), which showed that the chaetotaxy of the first abdominal segment is very similar in Cyphoderus, Troglobius (Cyphoderinae) and Trogolaphysa (Paronellini), and much reduced in relation to that seen in Lepidonella (Paronellinae, Bromacanthini), Pseudosinella and Seira (Entomobryidae). This feature, along with the presence of pseudopores behind the posterior row of setae on the fourth abdominal segment as seen in Troglopedetes, Trogolaphysa and Cyphoderinae (absent in Lepidonella and Entomobryidae), suggests that Cyphoderinae is more closely related to tribe Paronellini than Paronellini is to Bromacanthini and Entomobryidae, and that the subfamily Paronellinae is paraphyletic if Cyphoderinae is excluded. We propose including Cyphoderini as the apical group in Paronellinae together with Paronellini (Trogolaphysa and Troglopedetes).