Canadian toad
| Canadian toad | |
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| Canadian toad at Wagner Natural Area, Alberta | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Amphibia |
| Order: | Anura |
| Family: | Bufonidae |
| Genus: | Anaxyrus |
| Species: | A. hemiophrys |
| Binomial name | |
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Anaxyrus hemiophrys (Cope, 1886) |
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| Canadian toad range | |
| Synonyms | |
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Bufo hemiophrys Cope, 1886 |
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Bufo hemiophrys Cope, 1886
The Canadian toad (also Dakota toad, Anaxyrus hemiophrys) is a species of toad that ranges from the prairie regions of central Canada south to parts of United States upper midwest. It belongs to the family Bufonidae, the "true" toads. Its specific name is derived from the Latin word hemiophrys, meaning eyebrow, which refers to its pronounced cranial crest between and behind the eye.Anaxyrus hemiophrys displays the typical toad characteristics, they lack a tail and teeth, they have horizontal pupils and their dry skin is thick and warty.
The Canadian toad can grow to around 7.6 cm (3 in) in length. Fully grown adult males are usually 5.6 to 6.9 cm (2.2–2.7 in), while females are a little bigger between the ranges of 5.6 and 7.9 cm (2.2–3.1 in) and they weigh between 35 and 55 g. Their colouring is described by Cope (1886) as "brown, marked on the back with a median yellowish line, and two to three rows of brown spots of medium size on each side of it." Each spot has one to two tubercles in their centers which are redder in colour than the rest of the spots. He also identified two spots on the upper lip, one below the tympanum and a large spot that extends from below the parotid gland to near the front of the humerus. The parotid gland is narrow and secretes a toxin to protect it from predators. The toxins can cause irritation to the eyes and mouth and if it is ingested it can cause illness, but despite this toxin they are safe to handle.
The coronal crests of Anaxyrus hemiophrys are well defined. The interorbital crests are narrow, relatively sharp-edged, non-porous and are widely separated. They run relatively parallel throughout most of their length, as far posterior as the level of the coronal crests. Posterior to that level they flare laterally to join the postorbital crests, delimiting the anterolateral edge of the postcoronal plane. Postcoronal plane is clearly defined and sloped posteroventrally. It is smooth and subtriangular, its apex directed posteriorly and it ends at the foramen magnum. Its sides are delimited anteriorly by short parietal crests. Particularly useful externally is the interorbital crest shape. In Anaxyrus hemiophrys the posterior ends of the crests almost invariably diverge at least slightly where they join the postorbital crests (usually not evident externally). This provides the easiest way to distinguish Anaxyrus hemiophrys from its close relative Anaxyrus americanus, who share some of the same territory. In Anaxyrus hemiophrys the postorbital crests are absent and the interorbital crests are fused to form a boss between the eyes, whereas, in the Anaxyrus americanus the interorbital crests are well separated and join distinct postorbital crests at a right angle. The boss is a soft tissue structure characteristic of this genus. It is anchored by the previously discussed structures of the skull.
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Wikipedia