Rio Pescado Stubfoot Toad

Atelopus balios

A.[telopus] longibrachius.—Rivero, 1968:22.

A.[telopus] spurrelli.—Rivero, 1968:22.

HOLOTYPE.—AMNH 17638, female, from the Río Pescado, Guayas Province, Ecuador, collected by G. H. H. Tate, May 28, 1922.

DIAGNOSIS.—A member of the longirostris group, with long, thin legs and with heels overlapping when tibiofibulae are parallel to femora at right angles to body; first digit on forefoot distinct, not hidden in webbing; limbs smooth. Similar to longirostris, but differs in having a lighter ground color with darker spotting, while longirostris has a dark ground color with yellowish spots.

DESCRIPTION.—Snout from above rounded or with blunt point; outward curve of muzzle becoming inward curve from level of nostril to eye; snout, canthus, upper eyelid, and temporal region somewhat fleshy. Dorsum of snout weakly concave, rest of dorsum of head flat, lightly shagreened. Eye slightly bulging dorsally. Snout from side protrusive over lower jaw and upper lip, forming blunt point; nostril lateral, loreal region vertical or very slightly concave. Eye slightly overhung by fleshy margin of upper eyelid; temporal region more heavily shagreened than dorsum, and also heavily wrinkled. Dorsum almost smooth, very finely wrinkled; sides with wrinkles forming deep creases; chin and belly so heavily wrinkled that areas between wrinkles look like pustules.

Forelimb very slender, with forearm more fleshy than humeral region, dorsum thickly shagreened, ventral area wrinkled. When forearm is pulled back along body, second and fourth digits reach vent. Sole of forefoot fleshy, fleshy webbing encloses all but tip of first digit, extends as fringe to ends of other digits, giving them a flattened appearance, webbing between toes incised to a point about one quarter of distance to digit tips. All subarticular tubercles almost totally indistinguishable, as are both plantar and palmar tubercles, with latter occasionally forming low rounded hump. Males with horny excrescence on first digit of forefoot.

Hind limb slender, finely but densely shagreened dorsally, less dense laterally, giving way to wrinkling on ventral surface. Tibiotarsal articulation may reach to points between anterior edge of eye and anterior margin of tympanic area when carried forward along body. Heels touch or overlap when tibiofibulae are parallel to femora at right angles to body. Entire foot fleshy with thick webbing to tips of toes, first three toes almost totally obscured by webbing, which forms fringe on fourth toe from level of tip of third and fifth toes. No subarticular tubercles, very reduced outer metatarsal tubercle, almost indistinguishable in some individuals, no inner metatarsal tubercle.

COLOR IN ALCOHOL.—Dorsal ground color very light tan, with numerous rounded spots, completely separated from each other. Dorsum of legs, sides of body as dorsum of body, side of head with dark brown line from tip of snout through eye along side of head to shoulder, line either continuous or irregularly broken into spots along lower sides. Upper lip light, rest of body below stripe usually unicolor light yellowish white, a few individuals with scattered spots on belly. Ventral surfaces of limbs yellowish white, of feet dull yellow.

HOLOTYPE.—The holotype agrees with the description above in all characteristics for which no variation is described. Where the species shows variability, the holotype has the following characteristics: snout from above with blunt point, loreal region vertical. Tibiotarsal articulation reaches posterior corner of eye; heels overlap when tibiofibulae are parallel to femora at right angles to body. Outer metatarsal tubercle present, distinguishable. Color pattern as shown in Figure 14, lateral brown streak broken into series of spots, no spots on belly. Measurements: (in millimeters) snout to vent: 35.2; snout to end of coccyx: 33.5; knee to knee: 28.4; tibiofibula: 15.7; head length: 9.2; head width: 8.6; eye diameter: 3.0; snout to eye: 4.6; interorbital distance: 3.2; width of eyelid: 2.2.