Reptiles Database

Order Squamata
Suborder Amphisbaenia

Family Amphisbaenidae s.l. (Worm Lizards), incl. Blanidae, Cadeidae and Rhineuridae


Content: about 160 species in 18 genera (see list below).

Appearance: Amphisbaenians are limbless squamates whoses pectoral and pelvic girdles have been significantly reduced or are absent. Usually they have a distinctly annulated pattern of scutellation and rather short tails. Amphisbaenids are adapted to a burrowing life style and accordingly, their skulls are heavily ossified and their brain is entirely surrounded by the frontal bones. In contrast to other limbless lizards or snakes, which have a reduced left lung, the right lung of amphisbaenians is reduced in size.

Size: The total body length ranges from 10 cm to about 70 cm.

Distribution: Mostly Africa and South America with a few species in Europe and North America.

Habitat: Soil.

Behavior: Burrowing; The blunt-cone or bullet-headed genera (e.g., Amphisbaena, Blanus, Cadea Zygaspis) burrow by simple head-ramming. The spade-snouted taxa (Leposternon, Monopeltis) tip the head downward, thrust forward, and then lift the head. The Iaterally compressed keeled-headed taxa (Anops, Ancylocranium) ram their heads forward, then alternately swing it to the teft and right (Zug 1993).

Reproduction: usually oviparous, but some are live-bearing (namely some Loveridgea and Monopeltis).

Photo (left): Blanus cinereus; © Jakob Hallermann.

Relationships and sytematic notes: Rhineura is often put in a separate family, Rhineuridae. Kearney (2003) suggested to put Blanus in a separate family as well, the Blanidae, which can be diagnosed by their anteriorly truncated nasal bones and reduced clavicles (Kearney 2003).

Kearney (2003) also suggested to include the genera Aulura, Dalophia, Leposternon, and Monopeltis in the superfamily Rhineuroidea which she diagnosed by the following characteristics: strong craniofacial angle (also occuring in trogonophids), enlarged pectoral scales, a ventrally deflected retroarticular process, striated neural arches, denticulate posterior margins of the trunk vertebrae, ilium curving medially around anterior edge of vent, and an enlarged U-shaped occipital condyle.

Note that Kearney's Rhineuridae contains 1 extant genus, Rhineura, and 9 extinct genera (Dyticonastis, Hyporhina, Jepsibaena, Macrorhineura, Oligorhineura, Oligodontosaurus, Ototriton, Pseudorhineura, Spathorhynchus). Kearney's diagnosis of the Rhineuridae uses the following characteristics: small medial nasal process of premaxilla that does not separate the nasals in superficial view, a squared-off anterior edge of the snout, external naris opens ventrally, pterygoid-vomer contact, high maxillary tooth count, low maxillary tooth count, dentary process of coronoid overlapping dentary, and absence of posterodorsal rib processes. However, not all of these features can be ascertained in all the fossil taxa in this group.

Recently, Vidal et al. (2007) found that the genus Cadea is only distantly related to Amphisbaena in which it had been included previously. These authors erected a new family for the genus, Cadeidae Vidal & Hedges 2007.

List of Genera:

Amphisbaenidae

Blanidae

Cadeidae

Rhineuridae

Phylogenetic relationships according to Vidal et al. (2007)

Amphisbaenia_Vidal2007

Phylogenetic relationships according to Macey et al. (2004)

 

Single most parsimonious tree based on the analysis of 11,946 aligned nucleotide positions containing 5797 phylogenetically informative sites from 13 protein coding and 22 tRNA genes. Note that Gondwanan taxa, Trogonophidae (Diplometapon), and Amphisbaenidae (Amphisbaena and Geocalamus), are monophyletic. The two Laurasian families Rhineuridae (Rhineura) and Bipedidae (Bipes) represent successive, paraphyletic basal lineages indicating that amphisbaenian reptiles predate the breakup of Pangaea 200 million years ago. Modified from Figure 4 in Macey et al. (2004).

References:

Broadley,D.G., Gans,C. & Visser,J. (1976)
Studies on Amphisbaenians. (6). The Genera Monopeltis and Dalophia in Southern Africa.
Bull. Amer. Mus. Nat. Hist., New York. Vol.157 (5): 311-486

Gans,C. (1967)
A checklist of recent amphisbaenians (Amphisbaenia, Reptilia).
Bull. Amer. Mus. Nat. Hist. 135 (2): 63-100

Gans,C. (1971)
Studies on Amphisbaenians. (4). Genus Leposternon.
Amer. Mus. Nat. Hist., New York. Vol.144 (6): 379-464

Gans, Carl (1978)
The characteristics and affinities of the Amphisbaenia.
Transactions of the Zoological Society of London 34: 347-416

GANS, CARL, AND ELAZAR KOCHVA (1966)
A systematic review of Ancylocranium (Amphisbaenia: Reptilia). [Notes on amphisbaenids (22)].
Israel Jour. Zool., vol. 14, pp. 87-121.

Gans-C; Kraklau-D-M (1989)
Studies on amphisbaenians (Reptilia) 8. Two genera of small species from east Africa (Geocalamus and Loveridgea).
AMERICAN MUSEUM NOVITATES (No. 2944) : 1-28

Kearney, M. (2003)
Systematics of the Amphisbaenia (Lepidosauria: Squamata) based on morphological evidence from recent and fossil forms.
Herpetological Monographs 17: 1-74

Macey, J. Robert; Theodore J. Papenfuss; Jennifer V. Kuehl; H. Mathew Fourcade and Jeffrey L. Boore (2004)
Phylogenetic relationships among amphisbaenian reptiles based on complete mitochondrial genomic sequences.
Molecular Phylogenetics and Evolution 33 (1): 22-31

Vidal, Nicolas; Anna Azvolinsky, Corinne Cruaud and S. Blair Hedges (2007)
Origin of tropical American burrowing reptiles by transatlantic rafting.
Biol. Lett., doi:10.1098/rsbl.2007.0531