Crowned Bullfrog

morphology

H. occipitalis is a sizable flat ranid manifesting protruding eyes, numerous dorsal warts, and a minute inner metatarsal tubercle. This anuran exhibits complete webbing between all the toes and fingers. This large dorso-ventrally flattened ranid frog features warty skin, with eye and nostril dorsal placement. Viewed from above, the eyes are completely contained within the outline of the frog's head. Owing to the presence of numerous glands, the exterior skin is extremely slippery. (Rodel. 2000) The colour of the body and limbs is a yellow-green, olive or drab brown. Large dark green to blackish spots occasionally form rows, are exhibited on the dorsum. Spots of this same dark green to black present on the upper lip and on the extremities. A light green to yellow transverse line behind the eyes is exhibited in juvenile frogs,and often in adults as well. The outer elements of the thighs are marbled. The venter is white, occasionally punctuated with black spots.

African Amphibians

biology

This large frog is found over a relatively broad, but disjunctive, range of North Africa as well as sub-Saharan Africa. The sexually dimorphic anuran prefers savanna habitat, but is also found in grasslands and certain forests. Eggs are laid in slow moving heavily vegetated streams. As an important predator of mosquitos, Hoplobatrachus occipitalis may play a significant role in preventing spread of certain diseases such as malaria.

African Amphibians

associations

Hoplobatrachus occipitalis larvae prey on small aquatic animals like tadpoles and mosquitos, making them an important part of the food chain within temporary savanna ponds. As adults, they consume various other organisms. The loss of H. occipitalis as a predator, due to overexploitation of the species, could lead to increases in prey populations (Mohneke, 2010).

African Amphibians

distribution

The distribution of H. occipitalis is fundamentally disjunctive, including a swath in North Africa and a much larger range in sub-Saharan Africa. The North African range includes portions of Morocco, Algeria and Libya in the subcoastal areas of the Mediterranean Basin; these North African populations can be further regarded as isolated with sub-populations in southwestern Libyan Arab Jamahiriya, southeastern Western Sahara and nearby Mauritania, the Air mountains of Niger, and northern Mali. The sub-Saharan range extends from the Atlantic coast of West Africa, ranging eastward to Ethiopia, Chad, Eritrea, Sudan and south to Angola and Mozambique. Other specific sub-Saharan countries of occurrence include northern Zambia, western Congo, Senegal, Gambia, Guinea Bissau, Liberia, Sierra Leone, Guinea, Mali, Burkina Faso, Ivory Coast, Ghana, Togo, Benin, Niger, Nigeria, Cameroon, Equatorial Guinea (including the island of Fernando Pó), Congo, R.D. Congo, Central African Republic, Uganda, Kenya, Tanzania, Rwanda and Burundi. (Rödel.2000)

African Amphibians