New morphological and molecular data reveal an important underestimation of species diversity and indicate evolutionary patterns in European Lepidocyrtus (Collembola : Entomobryidae)

Abstract

The correct identification of morphological species is a key task for species richness estimation of any ecosystem. Although body colour is a widely used character identifying European Lepidocyrtus species, recent investigations using molecular data have revealed that species delineation using body colour can result in an underestimation of real species diversity because of the presence of cryptic species. Lepidocyrtus violaceus is a European species characterised by its dark violet body colour. Its wide distribution leads us to suspect that several cryptic species can be present within this morphospecies. Since traditional morphological characters have appeared insufficient for real diversity identification in Lepidocyrtus, new morphological characters were needed in order to describe the cryptic diversity detected by molecular data in this genus. Pseudopores are integumentary structures present in all Lepidocyrtus species, but the distribution of these structures has not been properly described in the genus, as well as in Entomobryioidea overall. In the present work we aimed to analyse whether L. violaceus is a monophyletic entity in Europe. Moreover, we aimed to determine if the position and number of pseudopores on the different parts of the body and appendages is a phylogenetically useful character in the identification of the species or superspecific entities. Fourteen populations of L. violaceus from five European countries, and another 25 Lepidocyrtus species from nine European countries have been studied. In total, 208 specimens have been analysed morphologically and half of them were studied molecularly using sequences of the genes COXII and EF-1α. Molecular data revealed that the widely distributed Lepidocyrtus violaceus morphospecies is a polyphyletic entity in Europe. Between 6 and 12 diferent cryptic species have been detected within this European morphospecies, and only the presence of pseudopores on the basal plate of the fourth abdominal segment has been found to be a promising diagnostic character between them. A common basal pattern of pseudopore distribution has been recognised in the European members of the genus, and also a diferential pattern within each European species group. As a general trend, an increase in the number of pseudopores has been detected from the most basal to the most derived species groups in the phylogeny of the genus in Europe.