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Fowler's Toad — Part 4
Since Bufo fowleri differs fundamentally from Bufo americanus, and occupies the same localities, it must be granted full specific rank. (The closer relationship that must have existed between these two toads in previous ages is shown in the fact that the tadpoles are almost identical in structure. The mouth of the tadpole of B. fowleri is more delicate, the delicacy especially noticeable in the papillae. The tadpoles differ in colour. (M. H. Hinckley, "On Some Differences in the Mouth Structure of Tadpoles." Proc. Bost. Soc. Nat. Hist., Vol. XXI, pp. 307-314).
Bufo hemiophrys, of which the type specimens--seven in number--were found in 1874, is to be looked for in Dakota and Manitoba, instead of in Montana, as stated by Cope. Owing to the misstatement in "Batrachia of North America," diligent search was made for this toad in northern Montana throughout the spring and summer of 1905 by several collectors, but no specimens came to light.
This toad differs from the species of the Pacific Slope (Bufo boreas) in the possession of bony ridges on the head, while it is like them in skin structure and arrangement of warts. It differs from the species of the Rocky Mountains and Western plains (Bufo l. woodhousei and Bufo cognatus) in having the underparts conspicuously spotted and in the arrangement of the cranial crests, but agrees in certain features, such as the foot structure. The species bears a superficial resemblance to Bufo fowleri.
The arrangement of the spots may be as follows: One obliquely set above each eye; one on the back, just within the parotoid gland on each side; three oval spots set obliquely and ranging along each side of the vertebral streak. Two similar spots back of and in line with the parotoid gland, and two or three others on the upper sides. Other more obscure spots may be present. Underparts light, unspotted; yellow posteriorly. Much yellow (especially in the case of young toads) on palm, sole, and on concealed surface of femur. Ends of fingers and toes dark-coloured.
Hand with one large palm tubercle; the remainder of the palm set with crowded small tubercles. Foot thick, with tarsal ridge. Toes slender, fourth toe much longer than the others. Web deeply indented. Sole tubercles large, both with cutting edge; the inner is at least three times as large as the outer. The tubercles under the toe-joints may be double.
Bufo cognatus, common toad of the Western plains, is one of our largest North American species. It is toad very distinctive in its characteristics, notwithstanding the fact that in localities where it is found with Bufo l. woodhousei, the two toads are usually confused.(See p. 93.) It can always be recognized by the bony elevation in front, above the nostrils and between the eyes anteriorly; by the large outer sole tubercle with its cutting edge; by the short femur and long foot.
Judging from the series of decidedly different sizes of this toad found in the spring, at least five years must be required for full growth to be attained.
The female Bufo cognatus seldom makes any sound. When taken in the hand, it shakes with wrath, but usually remains silent. The male however, "talks" in a voice resembling the squawk of a toy doll. This squawk of the Bufo cognatus is much like the sound produced by Bufo halophilus of California. The harsh note is given over and over again at brief intervals until the cause of annoyance is removed. The pitch of the note is low, ranging from B to A below middle C. In the midst of the harsh low-pitched notes, the toad sometimes surprises one by giving a cry pitched about two octaves above (usually A).
At the base of the throat of the male is a wrinkled black and purplish spot, which at first sight, one might judge the result of an injury. This is thin skin, lying fold upon fold, and can be extended into a vocal bladder of enormous size.
Bufo cognatus is not nearly related to the American Toad or to Bufo lentiginosus, but is closely connected with Bufo compactilis of the Southwest and Bufo quercicus of Georgia and Florida. The relationship shows itself not only in various technical details, but in visible external features. They each show the reduced femur and short leg, the short head and broad depressed body, diverging parotoid glands that descend on the shoulders, well-developed sole tubercles, deeply indented webs, and a vocal bladder at the base of the throat. The cranial ridges mark a point of variance among the three. The variation in size also is notable. Bufo quercicus is the smallest known toad in the world, measuring only an inch and a quarter in length. Bufo compactilis is medium in size, and Bufo cognatus is one of the largest toads in North America.