Dibamidae or blind skinks is a family of lizards characterized by their elongated cylindrical body and an apparent lack of limbs. Female dibamids are entirely limbless and the males retain small flap-like hind limbs, which they use to grip their partner during mating. They have a rigidly fused skull, lack pterygoid teeth and external ears. Their eyes are greatly reduced, and covered with a scale. They usually lay one egg with a hard, calcified shell, rather than the leathery shells typical of many other reptile groups.

The family Dibamidae has two genera, Dibamus with 23 species native to Southeast Asia, Indonesia, the Philippines, and western New Guinea and the monotypic Anelytropsis native to Mexico. Recent phylogenetic analyses place the dibamids as the sister clade to all the other lizards and snakes or classify them as sharing a common ancestor with the infraorder Gekkota, with Dibamidae and Gekkota forming the sister clade to all other squamates. Hoeckosaurus from the Oligocene of Mongolia represents the only fossil record of the group.

Characteristics

General appearance

Dibamids are burrower lizards characterized by their elongated bodies with blunt head and tail, and an apparent lack of limbs.

Limbs

Dibamids are lizards with highly reduced limbs but they are not completely limbless. Males and females have rudimentary poorly developed hind limbs containing a femur, tibia and fibula in males, and distal cartilage cap. These elements are more developed on Dibamus than in Anelytropsis. Female Dibamus lack the tibia and the fibula. with reduced kinesis and a more rigid skull for burrowing. The combination of fossorial habits and small size, contributes to the development of a skull configuration that is frequently found in other groups of burrowers and miniaturized species. Among those characteristics are the closure of the supratemporal fenestra and the post-temporal fenestra, the relative large braincase, tubular or scroll-like palatines and modified jaw suspension mechanism with the quadrate articulating with the lateral wall of the braincase. snakes, considering the organization of the skull and jaw muscles; or was proposed to be closely related to a group of fossorial skinks with elongated bodies and reduced limbs.

|clades=

The relationships within Dibamidae have only be assessed until recently in a phylogenetic analysis that included DNA sequences from seven nuclear genes and one mitochondrial gene for 8 species, seven species of Dibamus and the one species of Anelytropsis. This analysis shows that there are two major clades within Dibamidae, one that includes the one species form the genus Anelytropsis, Analytropsis papillous, and the species of Dibamus that are distributed along continental Southeast Asia (Dibamus greeri, Dibamus montanus, and Dibamus bourreti). The other clade includes species that are currently distributed in the peninsular Southeast Asia and Islands (Dibamus tiomanensis, Dibamus novaeguineae, Dibamus seramensis, and Dibamus celebensis). Those analyses found close relationships between Dibamidae and all other lizards with elongated bodies, limb reduction and usually, a fossorial habit like amphisbaenians, snakes or fossorial skinks.

  • Anelytropsis papillosus

Dibamus

  • Dibamus alfredi
  • Dibamus bogadeki
  • Dibamus booliati
  • Dibamus bourreti
  • Dibamus celebensis
  • Dibamus dalaiensis
  • Dibamus deharvengi
  • Dibamus dezwaani
  • Dibamus floweri
  • Dibamus greeri
  • Dibamus ingeri
  • Dibamus kondaoensis
  • Dibamus leucurus
  • Dibamus montanus
  • Dibamus nicobaricum
  • Dibamus novaeguineae
  • Dibamus seramensis
  • Dibamus smithi
  • Dibamus somsaki
  • Dibamus taylori
  • Dibamus tebal
  • Dibamus tiomanensis
  • Dibamus vorisi

An extinct monotypic genus, Hoeckosaurus was recently proposed from the description of fossil material from the early Oligocene of the Valley of Lakes in Central Mongolia.

The International Union for Conservation of Nature (IUCN) include some of the species of the genus Dibamus and the single species of Anelytropsis in the red list of endangered species, most are in the category of least concern, and two species, Dibamus kondaoensis and Dibamus tiomanensis are listed as nearly threatened and endangered respectively.

References

  • MorphoSurce, Dibamidae skull 3D CT-Scans
  • iNaturalist, dibamid observations
  • The Reptile Database