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A Production of

Loveridgea ionidesii, Round-snouted Worm Lizard
Dr. Jessie Maisano - The University of Texas at Austin
Loveridgea ionidesii
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skull
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Private Collection of Dr. Carl Gans (#1831)

Image processing: Dr. Jessie Maisano
Publication Date: 12 Jun 2003

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Loveridgea ionidesii occurs along riverbanks in the Southern District of Tanzania. Very little is known of its life history, except that it is a viviparous (live-bearing) species. Loveridgea is a member of Amphisbaenia, a lineage (160 species) of mostly limbless burrowing squamates. The amphisbaenian skull classically has been difficult to study due to its small size (this skull measures just 5.8 mm in length) and largely closed construction, but high-resolution X-ray CT offers a solution to these problems.

There are four major amphisbaenian groups: Bipedidae, the only one to have forelimbs; Amphisbaenidae, the most diverse (149 species) and widespread (to which Loveridgea belongs; see also Anops kingii and Geocalamus acutus); Trogonophidae, whose members use an oscillating excavation pattern (see Diplometopon zarudnyi); and Rhineuridae, represented by numerous fossils (see Rhineura hatcherii) but only one extant species. Amphisbaenians occur in northern and sub-saharan Africa, southwest Asia, the Mediterranean, South America east of the Andes, the West Indies, western Mexico, Baja California, the southeasternmost United States, and Cuba. They are generally poorly represented in collections, and little is known of their life history, because of their burrowing lifestyle.

head morphotypes

There are four basic amphisbaenian head morphotypes, each of which appears to correspond to a different burrowing mode: 'round-headed', 'shovel-headed', 'spade-headed', and 'keel-headed'. Loveridgea represents the 'round-headed' morphotype; this is readily apparent when compared to the 'keel-headed' Anops kingii.

Amphisbaenians, like other squamates, have paired evertible hemipenes, a transverse cloacal slit, and shed their skin in its entirety. They differ in that they have a highly modified skull architecture, a unique modification of the ear called the extracolumella, and skin with annuli (rings, like a worm -- hence the common name).

extracolumella

It is difficult to discern exactly where amphisbaenians fit in the squamate tree, as even the earliest-known fossil representatives already exhibit the highly derived cranial morphology seen in living forms. Phylogenetic analyses based on morphology tend to place amphisbaenians with the other two major limbless squamate clades -- snakes and dibamids; however, this may be due to convergence of characters correlated with a burrowing lifestyle rather than ancestry.

About the Species

This specimen resides in the private collection of Dr. Carl Gans of The University of Texas at Austin. No locality information is available. It was made available for scanning by Dr. Gans and Dr. Timothy Rowe of The University of Texas at Austin.

The scan revealed that the posterior portion of the skull is badly damaged; this is apparent in the animations above.

About this Specimen

This specimen was scanned by Richard Ketcham on 31 August 1998 along the coronal axis for a total of 231 slices, each slice is 0.025 mm thick with an interslice spacing of 0.025 mm.

About the
Scan

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

Gans, C., and D. K. Kraklau. 1989. Studies on amphisbaenians (Reptilia) 8. Two genera of small species from East Africa (Geocalamus and Loveridgea). American Museum Novitates 2944:1-28.

Gans, C., and E. G. Wever. 1972. The ear and hearing in Amphisbaenia (Reptilia). Journal of Experimental Zoology 179:17-34.

Kearney, M. In press. Systematics and evolution of the Amphisbaenia (Reptilia: Squamata) based on morphological evidence from fossil and living forms. Herpetological Monographs.

Links
Amphisbaenidae page from the EMBL Reptile Database

Literature
& Links
Spin of cranial endocast

(right) Pseudocolored reconstruction, whole sample, tissue on front half of skull rendered transparent. (left) Top portion of skull digitally removed showing internal details of the head structure. Visualization produced by Cambria Denison.

Additional
Imagery

To cite this page: Dr. Jessie Maisano, 2003, "Loveridgea ionidesii" (On-line), Digital Morphology. Accessed November 26, 2014 at http://digimorph.org/specimens/Loveridgea_ionidesii/.

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