Missing limbs | Bony triangles | Extra limbs | Skin webbings | Other limb abnormalities | Non-limb abnormalities


Deformed amphibian images

Below are a series of images that depict some of the more common malformations associated with Ribeiroia infection. The presence of these abnormalities is NOT diagnostic of parasite-infection, however, as there can be multiple causes of a single malformation type. The relative abundance of these different malformations also varies among species. For example, extra limbs often occur in response to Ribeiroia in some amphibians (e.g., Pacific chorus frogs), but not in many others.

These images are copyrighted and should not be reproduced without permission.

Missing limbs (hemi- and ectromelia)


Missing limbs can vary in severity from a missing foot (e.g., upper middle and upper right) to the complete absence of one or more limbs (lower middle and lower right). Missing limbs can occur in either fore- or hind limbs. Illustrated species include the northern leopard frog (upper left, upper right, and lower left), the American toad (upper middle, lower middle), and the Pacific chorus frog (lower right). Copyright Pieter Johnson.


Bony triangles (taumelia)


Bony triangles, which are also known as taumelia or bone bridges, involve longbones that fold back upon themselves, often leading to a triangular appearance and a truncated limb. In the lower right image, the frog has been cleared and double-stained to reveal the bone structure. In some cases, multiple "triangles" occur in a single limb, leading to severe truncation of the limb (e.g., see lower middle). Illustrated species include the northern leopard frog (upper left, lower left), the American toad (upper middle, lower middle), and the Pacific chorus frog (upper right and lower right). Images are copyright of Pieter Johnson.


Extra limbs (polymelia)


Extra limb and limb elements (e.g., digits) are among the most graphic of reported malformations and therefore frequently referenced in discussions of deformed amphibians. However, not all species are equally likely to exhibit extra limbs in response to Ribeiroia infection. Some, such as Pacific chorus frogs (upper middle) often suffer extra limbs or digits; in others, however, extra limbs may be rare. Extra limb elementsmost often occur in the hind limbs and can vary in severity from an extra digit to multiple supernumerary limbs. Illustrated species include the northern leopard frog (upper left, upper right, lower middle), the American toad (lower left), Pacific chorus frog (upper middle), and American bullfrog (lower right). Upper middle and lower right images are copyright of Steve Holt (stockpix.com) while remaining images are copyright Pieter Johnson.


Skin webbings (cutaneous fusion)


Skin webbings or cutaneous fusion involve and envelope of skin that connects two limb elements (e.g., thigh and calf), often restricting the ability of the affected animal to extend its limb. Webbings can vary from mild to severe, sometimes affecting both hind limbs (bilateral cutaneous fusion, see right image). Illustrated species include the northern leopard frog (left and middle) and the American toad (right). Images are copyright of Pieter Johnson.


Other limb abnormalities


In addition to the categories listed above, amphibians can exhibit a broad diversity of other limb abnormalities. These can include abnormalities such as limb extension or flexure (above left), in which one of the limbs is in a permanently flexed position; this can also occur in association with a truncated longbone. Other abnormalities include micromelia, in which one limb is abnormally small or poorly developed.Illustrated species include the northern leopard frog (left and right) and the American toad (middle). Images are copyright of Pieter Johnson.


Non-limb abnormalities


Finally, amphibians can suffer from many other abnormalities that do not involve the limbs (although these are less likely to be caused by Ribeiroia). Missing eyes (above left) can be due to developmental irregularities or to trauma. In the above middle image, the left eye has developed under the skin next to the right eye, rather than in the left eye orbit. In the above right image, a leopard frog that is missing its left limbs has developed spinal curvature and internal abnormalities. Illustrated species include the northern leopard frog (left and right) and the Pacific chorus frog (middle). Middle image copyright of Steve Holt (stockpix.com); other images are copyright of Pieter Johnson.

 

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