Ceratovacuna and Pseudoregma are important groups in Cerataphidini (Hemiptera, Hormaphidinae) that not only produce soldier aphids in galls on the primary hosts but also produce horned soldiers on the herbaceous secondary hosts. However, due to sampling bias in previous studies, the phylogenetic relationships of these two genera remain inconclusive. In this study, based on more extensive sampling and examination of both mitochondrial (cytochrome c oxidase subunit I (COI); cytochrome b (Cytb)) and nuclear (elongation factor-1α (EF-1α); long-wavelength opsin (LWO)) genes, we reconstructed the phylogenetic relationships of Ceratovacuna and Pseudoregma. Phylogenetic analyses, along with morphological evidence, suggested that these two genera belong to the paraphyletic groups with species clustered into three main groups. The monophyly of Ceratovacuna and Pseudoregma as a whole was generally supported by all analyses. Monophyly of Pseudoregma was also supported. The estimated divergence times demonstrated that diversification of Ceratovacuna and Pseudoregma occurred approximately at 10 mya. The relatively low resolution for the basal relationships of the three main clades may indicate that these two genera have experienced a rapid radiation along with speciation burst of their secondary hosts during the late Tertiary.

Morphological classification of snail shells is sometimes arbitrary and misleading in correct species delimitation. This topic is investigated in four nominal species of the minute gastropods of the genus Vallonia (V. pulchella, V. excentrica, V. costata and V. enniensis). First, individuals are classified according to their shell morphology. Second, variation in ribosomal internal transcribed spacer 1 DNA (ITS-1 rDNA) is analysed. Using a cladistic approach, the nucleotide positions of the ITS-1 are elucidated on apomorphic and plesiomorphic character states (outgroup=Acanthinula aculeata; Valloniidae). The molecular data yield evidence that the morphospecies V. excentrica is a paraphyletic group, comprising just a loose arrangement of individuals with similar shells. Data on fossil shells and putative divergence time are also elucidated. In the monograph on Vallonia it has been suggested that the split between the branch of V. costata and the branch of V. pulchella, V. excentrica and V. enniensis could have been in the upper Cretaceous. Based on the ITS-1 sequence alignment and the number of variable nucleotide positions, it is suggested that the last common ancestor of both branches lived at some time during the Miocene or even the Pliocene. Therefore, the fossil stem lines of Vallonia should be newly interpreted.