Sonja's Spiny Frog
Species Description: Rödel, M-O, Kosuch J, Veith M and Ernst R. (2003) First record of the genus Acanthixalus Laurent, 1944 from the upper Guinean rain forest, West Africa, with the description of a new species. Journal of Herpetology 37: 43–52.
The dorsum and extremities are yellow-green and bear numerous white warts with black spines. Three black crossbands as well as black spots and lines are present on the dorsum, as well as a transverse black band on the sacral region. A single black triangular mark is located between the eyes, and paired black triangles are visible on the shoulders, with each triangle apex pointing towards the posterior. Black transverse bands are also present on the upper lip, femur and tibula fibula. Flanks are green to white. Ventral surfaces are gray brown with black markings and white warts lacking black spines. Gular glands (present on males) are beige-colored. The anal region is bright yellow. Finger and toe discs are white with a black spot above and beige below; heels are orange to yellow. This frog is capable of metachrosis, with colors darkening almost to black in the sunlight, within a few minutes. The iris is black with white stripes radiating outward (Rödel et al. 2003).
Juveniles are more brightly colored, with the dorsal ground color often being yellow to orange, and the ventral side orange as well. Juveniles also have four enlarged yellow warts on the neck (Rödel et al. 2003).
Tadpoles are similar to those of A. spinosus but have longer tails. The body is compact, rounded dorsally and slightly depressed laterally. Eyes are very small and lateral. The oral disc is subterminal, with a tooth formula 1: 2 + 2/ 3, wide serrated, curved jaw sheaths, a single row of lateral papillae on either side and two rows of caudal papillae (medially uniserial). The spiracle is sinistral and the vent is medial. The tail tip is broadly rounded (Rödel et al. 2003).
Tadpoles taken directly from treeholes were a fleshy violet color, which quickly changed to black in the sunlight. In some tadpoles, the tail tip is almost transparent (Rödel et al. 2003).
Distribution and Habitat
Country distribution from AmphibiaWeb's database: Cote d'Ivoire, Ghana
Life History, Abundance, Activity, and Special Behaviors
Clutches are attached to the walls or ceiling within a water-filled tree cavity. The egg masses are flat immediately after oviposition, changing to hemispheric soon thereafter and measuring 2-4 cm in diameter. The mean clutch size was 9.3 eggs. Eggs are whitish gray with a darker pole. One female in captivity oviposited three clutches within 21 days (Rödel et al. 2003).
Tadpoles first orient horizontally within the egg, changing to a head-up vertical position as development progresses. They begin dropping into water 11-14 days post-oviposition. Metamorphosis is complete within three months. Tadpoles have been reported to be at least partly carnivorous (Rödel et al. 2003).
Trends and Threats
Possible reasons for amphibian decline
General habitat alteration and loss
IUCN, Conservation International, and NatureServe. (2006). Global Amphibian Assessment: Acanthixalus sonjae. www.globalamphibians.org. Accessed on 21 August 2008.
Rödel, M.-O., Gil, M., Agyei, A.C., Leaché, A.D., Diaz, R.E., Fujita, M.K., and Ernst, R. (2005). ''The amphibians of the forested parts of south-western Ghana.'' Salamandra, 41, 107-127.
Rödel, M.O., Kosuch, J., Veith, M., and Ernst, R. (2003). ''First record of the genus Acanthixalus Laurent, 1944 from the Upper Guinean Rain Forest, West Africa, with the description of a new species.'' Journal of Herpetology, 37(1), 43-52.
Schiøtz, A. (2007). Treefrogs of Africa: Addenda and Corrigenda 2007. Personal communication, available as .pdf file from http://zoologi.snm.ku.dk (english/staff/schiøtz/list of publications).
Originally submitted by: Kellie Whittaker and Arne Schiøtz (first posted 2008-08-21)
Edited by: Kellie Whittaker, Michelle S. Koo (2021-08-22)
Species Account Citation: AmphibiaWeb 2021 Acanthixalus sonjae: Sonja's Spiny Frog <https://amphibiaweb.org/species/6561> University of California, Berkeley, CA, USA. Accessed May 17, 2022.
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Citation: AmphibiaWeb. 2022. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 17 May 2022.
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