Description
Males of this relatively large species of Hyloxalus attain a snout-vent length of 29.9 mm and females, 36.1 mm. The discs on the fingers and toes are nearly truncate and expanded to about twice the width of the penultimate phalanges. Finger I is equal in length to Finger II, and Finger III is not swollen in males. Lateral fringes are present on the fingers and toes. An outer tarsal fold and tarsal tubercle are absent; the inner tarsal fold is curved on the distal two-thirds of the tarsus. The toes are about two-thirds webbed. The dorsum is pale brown with irregular dark brown spots and transverse bars on limbs; the posterior surfaces of the thighs are tan. A dark brown stripe across tip of snout passes through the nostril to the eye and continues across the tympanum, above the insertion of forelimb and onto the flank to the groin. Pale dorsolateral and ventrolateral stripes are absent; a dull white oblique lateral stripe extends from the midflank to the groin. A dark brown crescent-shaped mark on the anterior surface of the upper arm is not continuous with the dark brown stripe on body. The venter is gray in males, whereas in females the belly is white and the throat and chest are bright yellow. The digital scutes grayish tan, and the upper lips are pale creamy tan; the iris is reddish bronze with small black flecks and median horizontal brown streak. A median lingual process is absent, and the testes are white (Duellman 2004).

A tadpole in Stage 25 has a body length of 12.5 mm and a total length of 30.0. The body is globular and wider than high. The snout is bluntly rounded in dorsal view and rounded in profile. The small eyes are situated dorsally, directed dorsolaterally, and not visible from below. The spiracle is sinistral with a short tube attached to body throughout its length; the spiracular opening is directed nearly posteriorly just below the midline at about midlength of the body. The cloacal tube is short, cone-shaped, dextral, and attached to the ventral fin. The caudal musculature is robust, about equal in height throughout the proximal two-fifths of the tail, and gradually diminishes to a pointed tip. The dorsal fin originates on the proximal part of the caudal musculature, reaches its greatest height at about two-thirds the length of the tail, and declines to an acutely rounded tip; ventral fin originates on the body and is highest at the midlength of the tail. The oral disc is directed anteroventrally. The median half of the anterior labium is bare; elsewhere the labia bear a single row of small, subconical marginal papillae. The jaw sheaths are narrow and finely serrate; the anterior sheath forms a broad arch, and the posterior sheath is broadly V-shaped. The labial tooth row formula is 2(1)/3; A2 is the longest, and P1 is the shortest. The body is brown, and the tail is pale orange.

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Peru

View distribution map in BerkeleyMapper.

This species is known only from an elevation of 500 m near the eastern base of the Cordillera Central and from an elevation of 520 m near the northern end of the Cordillera Central in northern Peru. The frogs were under rocks in a streambed by day; at night they were perched on wet boulders in the streambed. Tadpoles were in a pool in a stream in a rocky ravine.

Life History, Abundance, Activity, and Special Behaviors
The call is a series of about 10 whistle-like notes.

References

Duellman, W. E. (2004). ''Frogs of the genus Colostethus (Anura; Dendrobatidae) in the Andes of northern Peru.'' Scientific Papers of the Natural History Museum, University of Kansas, 35, 1-49.

Species Account Citation: AmphibiaWeb 2007 Hyloxalus sordidatus <https://amphibiaweb.org/species/6362> University of California, Berkeley, CA, USA. Accessed Jan 14, 2025.

Citation: AmphibiaWeb. 2025. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 14 Jan 2025.

AmphibiaWeb's policy on data use.