of the alpine newt. It therefore has priority over Mesotriton and is now the valid genus name. "Ichthyosaura", Greek for "fish lizard", refers to a nymph-like creature in classical mythology. Subspecies Four subspecies (see table below) were recognised for the alpine newt by Roček and colleagues (2003), followed by later authors, while some previously described subspecies were not retained. The four subspecies correspond only in part to the five major lineages identified within the species (see section Evolution below): The western populations of the nominate subspecies I. a. alpestris, together with the Cantabrian I. a. cyreni and the Apennine I. a. apuana form one group, while the eastern populations of I. a. alpestris are genetically closer to the Greek I. a. veluchiensis. Differences in body shape and colour between the subspecies are not consistent. Several authors argued that the ancient lineages of the alpine newt might represent cryptic species. Four species were therefore distinguished by Raffaëlli in 2018, but Frost considers this premature. Evolution Alpine newt populations have separated since the Early Miocene, around 20 million years ago, according to a molecular clock estimate by Recuero and colleagues. Known fossil remains are much more recent: they were found in the Pliocene of Slovakia and the Pleistocene of Northern Italy. An older, Miocene fossil from Germany, Ichthyosaura randeckensis, may be the sister species of the alpine newt. Molecular phylogenetic analyses showed that alpine newts split into a western and an eastern group. Each of these again contains two major lineages, which in part correspond to described subspecies (see section Distribution and subspecies above). These ancient genetic differences suggest that the alpine newt may be a complex of several distinct species. Higher temperatures during the Miocene or sea level oscillations may have separated early populations, leading to allopatric speciation, although admixture and introgression between lineages probably took place. Populations from Vlasina Lake in Serbia have mitochondrial DNA that is distinct from and more ancient than that of all other populations; it may have been inherited from a now extinct "ghost" population. The Quaternary glaciation probably led to cycles of retreat into refugia, expansion and range shifts. Description The alpine newt is medium-sized and stocky. It reaches length in total, females measuring roughly longer than males, and a body weight of 1.4–6.4 g. The tail is compressed sideways and is half as long or slightly shorter than the rest of the body. During