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Hemiphractus johnsoni

By Glenda Holland

Geographic Range

Hemiphractus johnsoni is thinly distributed over a vast range. It occupies elevations of 300m to 1910m in the Northern Andean slopes of Colombia, the upper Amazon Basin, and lower Amazonian slopes of the Andes from Ecuador to Northern Bolivia (Trueb 1974).

Habitat

Hemiphractus johnsoni inhabits dense, lowland tropical rainforests (Trueb 1974).

Physical Description

Hemiphractus johnsoni is sexually dimorphic; females are significantly larger than males. Snout to vent length in males averages approximately 52.9mm, while females average 77.2mm in length. There are scattered tubercles on the dorsal surface and forearms, and poorly developed tubercles on the hind limbs, of all hemiphractine species. The granular eyelids also have one or two enlarged conical tubercles. On the tip of the snout of H. johnsoni is a small, triangular and dorsoventrally flattened, fleshy proboscis. The shape of this proboscis is one of the ways H. johnsoni differs from the other hemiphractine species. A unique feature in H. johnsoni is the presence of a small, round post- orbital depression with a light crossbar; conversely H. johnsoni lack the provomerine teeth that other hemiphractine species possess. The color pattern of the dorsum is tan-brown with reddish mottling and darker spots. The forelimbs and hind limbs are a pale ground color with dark transverse. The outer digit of the unwebbed hands are noticebly darker than the inner digits. The back feet have basal webbing and the adhesive discs of the toes are slightly smaller than those of the fingers (Trueb 1974).

Development

Reproduction

Genus Hemiphractus is unique in that the eggs undergo direct development in a brood pouch on the dorsum of the female (Duellman and Trueb 1986). In the month of July, an H. johnsoni was found with seventeen eggs in her dorsal pouch. Another specimen wes found with eighteen young attached to her back. However, the average number of young associated with adult females was only eleven (Trueb 1974).

  • Key Reproductive Features
  • gonochoric/gonochoristic/dioecious (sexes separate)

Behavior

When threatened, hemiphractine species show a "gaping behavior" involving the frog opening its mouth as wide as possible. Because the Hemiphractinae lack both vocal sacs and vocal slits, mating calls and breeding congregations are unknown. At night H. johnsoni have been found perched on low branches 0.3m to 0.7m above ground (Trueb 1974).

Food Habits

Little is known of the feeding habitats of H. johnsoni, but insects and other small invertebrates probably constitute most of the diet, as in other hylid frogs. Lizards are not normally part of a small frog's diet, but a lizard was once found in the stomach of a related hemiphractine specie (Trueb 1974).

Conservation Status

The population status of this species is unknown, but it is undoubtedly threatened by the destruction of primary rainforest.

Other Comments

Hemiphractus johnsoni is the most generalized species in the subfamily Hemiphractinae. This suggests that it may resemble the ancestral hemiphractine that presumably evolved from a neotropical relative in the family Hylidae ("true" treefrog group) (Trueb 1974). Though interesting in appearance and their reproductive behavior, the Hemiphractinae have not been as thoroughly researched as some other tropical anurans.

Contributors

Glenda Holland (author), Michigan State University, James Harding (editor), Michigan State University.

Glossary

Neotropical

living in the southern part of the New World. In other words, Central and South America.

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bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

coastal

the nearshore aquatic habitats near a coast, or shoreline.

ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

metamorphosis

A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

rainforest

rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.

References

Duellman, W., . Trueb. 1986. Biology of Amphibians. New York: McGraw-Hill, Inc..

Trueb, L. 1974. Systematic Relationships of Neotropical Horned Frogs, genus Hemiphractus (Anura, Hylidae). Pp. no. 29 in Occasional Papers of the Museum of Natural History, the University of Kansas. Lawrence: Museum of Natural History, University of Kansas.

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