American Discoglossoid Toad

Ascaphus truei Stejneger

Colour: Dull reddish brown, with a few indistinct blackish markings on the back. A dusky band between the eyes. The top of the head in front of this band pale reddish grey narrowing in the midline in front and bordered on each side below the line of the canthus rostralis by a band of black. This black band extends backward through the eye to the shoulder along the lower border of the parotoid gland. A black spot below the arm insertion. Posterior surface of arm irregularly spotted. Femur, tibia, and under side of foot edged by an irregular dark band which is sometimes edged with white. Underparts light, clouded with dark, especially across the breast. Fingers and toes tipped with light.
Measurements: Size small; i.e. length 1 1/2 inches. Head slightly broader than long. Nostril nearer to the eye than to the tip of the muzzle. Space between eyes equal to width of eyelid. Arms and legs relatively long; arm, 1 inch; leg (total length), 2 1/4 inches. Length of leg to heel equals length of body forward to eye. Tibia longer than femur.
Structure: Skin granular, slimy, wrinkled, and irregularly warty above. Smooth and wrinkled below. Parotoid gland elongated, extending from the eye backward toward the shoulder. A narrow elongated gland on the side, corresponding in position to the lateral fold of frogs. Head flat; muzzle elongated, abruptly descending on the sides, obtusely pointed in front. Canthus rostralis prominent. Ear hidden. Fingers long and slender; three palm tubercles, no tubercles under the joints. Foot but slightly webbed; no tarsal fold; inner sole tubercle medium in size; no tubercles under the joints.
Range: One specimen only of Ascaphus truei has been found. Humptulips, Washington, 1897.

This curious little batrachian (a member of the Discoglossidae, (see p. 8) is the lowest known form of the Salientia in North America. In fact, no other Discoglossoid toad has been found in the Western Hemisphere, and the discovery of this one in 1897 marks one of the most important steps in the history of the Batrachology of North America.

Although having the form of the Tailless Batrachian, and many of its structural characteristics, such as parotoid glands and a tongue free behind, it has a skeleton showing the fundamental features in a primitive condition, as in the Tailed Batrachians or Salamanders. It thus supplies an important item in the story of the evolution of the Salientia.

The geographical distribution of the Discoglossoid toads has been most interestingly worked out by Dr. Leonhard Stejneger, of the National Museum. (1905. A Resume of the Geographical Distribution of the Discoglossoid Toads, in the Light of Ancient Land Connections. Leonhard Stejneger. American Geographical Society, vol. xxxvii, No. 2, pp. 91-94. Oct. 20, 1905. Science, p. 502. The Geographical Distribution of the Bell-Toads. Leonhard Stejneger.) He makes the region southeast of the Himalayas, in Asia, the original home of the family. From here they radiated to New Zealand, in early Cretaceous times, to western America (over the land bridge that existed between Asia and North America) in upper Cretaceous times, and to western Europe in early Tertiary times. Curiously enough, although at the moment of publication of his theory no Discoglossoid toad had ever been found in the region indicated as the centre of radiation, a new species (Bombina maxima Boulenger. Tong Chuan Fu, province of Yunnan.) was announced from there one month later by Boulenger.

FAMILY II. PELOBATIDAE: THE SPADEFOOT TOADS (Refer to pp. 7, 8 and 43.)