Anguis
Anguis is a genus of legless lizards in the family Anguidae, consisting of five extant species commonly known as slowworms or blindworms. These reptiles are characterized by their elongate, snake-like bodies lacking external limbs, smooth scales, and a maximum length of up to 50 cm in some species. Native to the Western Palearctic region, they are distributed across much of Europe and into western Asia, favoring temperate and humid habitats such as grasslands, woodlands, and gardens.[1][2][3] The genus Anguis, established by Linnaeus in 1758, derives its name from the Latin word for "snake," reflecting its superficial resemblance to serpents despite being true lizards. The recognized species include A. fragilis (common slowworm), A. colchica (eastern slowworm), A. graeca (Greek slowworm), A. veronensis (Italian slowworm), and A. cephallonica (Peloponnese slowworm), each adapted to specific subregions within their overall range. Phylogenetic studies indicate that Anguis represents an ancient lineage within Anguidae, with divergence events dating back millions of years, contributing to their morphological uniformity and ecological specialization.[1][4][5] Slowworms are ovoviviparous, giving birth to live young after internal development of eggs, and exhibit slow, deliberate movements that belie their name. They primarily feed on invertebrates like slugs, worms, and insects, playing a beneficial role in garden ecosystems by controlling pests. Despite their widespread occurrence, populations face threats from habitat loss and road mortality, though they are generally not considered endangered across their range. Hibernation occurs from October to February or March in burrows or under cover, aiding survival in cooler climates.[3][2][6]Taxonomy and Phylogeny
Etymology and History
The genus name Anguis derives from the Latin word for "snake," reflecting the legless, elongated body form of its members that mimics serpentine reptiles.[7] Carl Linnaeus formally established the genus in the 10th edition of Systema Naturae in 1758, with Anguis fragilis—the common slow worm—as the type species.[7] Early taxonomic treatments largely treated the genus as monospecific under A. fragilis, but accumulating morphological evidence in the late 20th century hinted at cryptic diversity, particularly in southern European populations. A major revision occurred in 2010 when Gvoždík et al. analyzed mitochondrial (ND2 and tRNAs) and nuclear (C-mos and PRLR) DNA sequences across the Western Palearctic range, uncovering deep genetic divergences within A. fragilis sensu lato and confirming it as a species complex. Their findings supported the recognition of A. cephallonica as a valid species and elevated two lineages to full species status: A. colchica (eastern Europe to Iran) and A. graeca (southern Balkans), each with distinct phylogeographic structuring linked to Pleistocene refugia. Building on this, Gvoždík et al. in 2013 examined Italian Peninsula populations using similar genetic markers (mtDNA cyt b, nDNA PRLR) alongside morphology, identifying an ancient basal lineage divergent since the Miocene.[8] They resurrected the taxon Anguis veronensis Pollini, 1818—originally described from Verona, Italy—as a full species, distinguished by unique haplotypes, subtle cranial differences, and a distribution spanning the Italian Peninsula, southern Alps, and southeastern France.[8] This elevation resolved prior subspecific uncertainties and highlighted the role of vicariance events, such as Alpine orogeny, in the genus's diversification.Classification and Species
The genus Anguis is classified within the family Anguidae, subfamily Anguinae, a group of legless lizards characterized by their elongated bodies and distribution across the Northern Hemisphere.[9] Phylogenetic analyses based on molecular data, including mitochondrial and nuclear genes, have resolved the relationships among Anguis species, revealing five distinct genetic clades that correspond to the recognized extant taxa. A key study using multilocus datasets identified these clades as deeply diverged lineages originating from an ancient radiation, with A. cephallonica as the basal species and the remaining four forming a "fragilis complex" clade supported by nuclear DNA, though mitochondrial data show some discordance suggestive of historical introgression.[9] Five extant species are currently recognized in the genus Anguis, each distinguished primarily by genetic markers such as sequence divergences in cytochrome b and nuclear loci (e.g., >5% mitochondrial divergence between clades), alongside subtle morphological traits like mid-body scale row counts and head scalation patterns used in taxonomic diagnoses.[10] These species are allopatric or parapatric, with contact zones exhibiting hybridization in some regions, such as between A. fragilis and A. veronensis in southeastern France.[10] The following table summarizes the species, their common names, and primary distributions:| Scientific Name | Common Name | Primary Distribution |
|---|---|---|
| Anguis cephallonica Werner, 1894 | Peloponnese slow worm | Peloponnese Peninsula, southern Greece |
| Anguis colchica Nordmann, 1840 | Eastern slow worm | Eastern Europe to western Russia, northern Turkey, Caucasus, northern Iran |
| Anguis fragilis Linnaeus, 1758 | Common slow worm | Western and central Europe, from Iberian Peninsula and British Isles to southeastern Europe and western Russia |
| Anguis graeca Bedriaga, 1884 | Greek slow worm | Balkan Peninsula, including Greece, Albania, and North Macedonia |
| Anguis veronensis Pollini, 1818 | Italian slow worm | Italian Peninsula and southeastern France |