Heleophryne depressa FitzSimons, 1946
The specific epithet depressa is from the latin "depressare" meaning "to flatten," which is in reference to the animal's vertically compressed head.
Heleophryne depressa is a member of the family Heleophrynidae, a group of small South African frogs known as ghost frogs because of their occurence in Skeleton Gorge. It exhibits a strongly depressed head and body. This species was originally thought to be a subspecies of another member of this family, H. purcelli, but was soon described as a separate species with a narrower interorbital space and proportionately longer leg length.
Heleophryne depressa is much more strongly depressed than specimens of H. purcelli from the Jonkershoek and Stellenbosch areas. This is especially noticeable on the snout of the animal. The interorbital space is also narrower and the leg length proportionately longer (Fitzsimons, 1946).
The flattened aspect and posture of the animal allows it to escape into narrow fissures. When a larva, the tadpole scrapes algae into its mouth, and escapes from predators or intruders by detaching and floating downstream (du Preez and Carruthers, 2009).
The tadpole of this species can grow up to 60 mm in length. It has a streamlined body with a large oral disc as a sucker, used to stay stationary in quick-moving mountain streams. It has a muscular tail that is bluntly rounded and dark at the tip, and a dorsal fin that is deeper than the ventral one. The body is grey to brown, similar to the rocks in the habitat. It has narrowly spaced nostrils which are closer to the eyes than to the tip of the snout. Its spiracle is on the lower half of the tadpole, pointing backwards at 40°. It has no jaw sheaths (du Preez and Carruthers, 2009).
Heleophryne depressa lacks the metacarpal tubercle on the first finger that is found in H. rosei. In addition, it has a horizontal line through its eye and webbing on the last phalanges of the fifth toe, which H. rosei does not exhibit (du Preez and Carruthers, 2009)
The head and body of this frog are very strongly depressed. The depth of its snout is less than the diameter of its eye. The interorbital space is less than the breadth of the upper eyelid or the internarial space. Its eye diameter is just over 3.5 times the breadth of the head, and the internarial space is equal to the distance between the nostril and the eye, or to the breadth of the upper eyelid. The leg, from the vent to the heel-fold is subequal to the distance from the tip of the snout to the vent. It has expanded terminal disks on its fingers, especially on the 3rd and 4th fingers, where the transverse diameter is subequal to the interorbital space. It has completely webbed toes.
There are small horny asperities over the entire upper surface of the frog, but more on the snout, margin of the lips, and the anterior part of the arm. These asperities don't go through the skin on the back, hindlimbs and sides, but rather are marked by raised white dermal points. The belly of the frog is granular, and the asperities on the lower side of the body are only on the edges of the lower jaw, the sides of the belly, and one mesial patch on the chest. In males, the cloaca is directed ventrally whereas it is directed posteriorly in females. Breeding males have loose dorsal skin, swollen forearms, and spines and its chest and inner fingers (du Preez and Carruthers, 2009).
The frog ranges from light to dark olive on the dorsal surface, with many large patches of deep marroon or purplish brown. These blotches are irregular and edged narrowly with white. In addition, there are white specks scattered on the back and limbs, corresponding to the aforementioned asperities that have not yet pierced the skin. The limbs have dark crossbars that are narrower than the space between them. The lower surface is cream to yellow, and the underside and back of the thighs are bright yellow to orange (Fitzsimons, 1946).
The dimensions of a typical male are 43.8 millimeters from the snout to the vent, with a maximum size of 44.5 mm. Females are slightly larger than males (du Preez and Carruthers, 2009). The head is 4.7 mm in depth and 17.6 mm in breadth. The forelimbs are 28.7 cm long, the hindlimbs 43.8 cm long, and the foot is 32.6 cm long from the heel-fold to the tip of the fourth toe. The tibia is 23.2 cm long, and the breadth of the disk on the third finger is 3.3 mm (Fitzsimons, 1946).
Heleophryne depressa is found in the Cederberg range to the north and the west of the Breede and Berg Rivers in the Eastern region of South Africa (du Preez and Carruthers, 2009).
The frog lives in clear mountain streams, and are often found stationary and well-camouflaged among the stones on the sandy bottom (Fitzsimons, 1946).
Heleophryne depressa can take up to two years to metamorphose (du Preez and Carruthers, 2009).
The call of Heleophryne depressa consists of two to four soft bell-like pings (du Preez and Carruthers, 2009).