Description
Astylosternus ranoides is a slender-bodied West African frog in which males range from 41.5 - 50.5 mm in snout-vent length, with an average of 46.7 mm. This species has a flat head with a long snout and small, rounded canthus rostralis. The tympanum to eye ratio is 75%. The dorsal integument is mostly smooth with small wrinkles. In males, spines are present and distributed broadly on the abdomen. Small spines can also be observed on the tympanic region, under the upper and lower limbs, and across the dorsum. The hands have round subarticular tubercles with no supplementary tubercles at the base of the fingers. The feet have a small amount of webbing, but the toes have a thin (¼ mm) fringe of skin. Outside of the mating season, these skin folds regress. In males, the toe tips are not dilated or spatulated, but they are weakly spatulate in females (Amiet 1977). The last phalanx of toes II–V is recurved and can protrude through the ventral skin of the toe, likely used to defend the frog by scratching potential predators (Blackburn et al. 2008). Males have a single nuptial pad that is thicker than in other species. During the mating season, males have thickened granulations under the mandible and the pectoral region (Amiet 1977).

The tadpoles have a body length to total length ratio of 34.1%, the ventral-fin-height to dorsal-fin-height ratio is 81.8%. The tadpole has only two anterior papillae on each side with 15 short roundish posterior papillae. The rostral gaps are large and the jaw sheaths are massive and serrated. The upper and lower jaws are both more or less U-shaped (Griesbaum et al. 2019).

Adult dorsal coloration is generally beige or yellowish brown. An intraocular bar stretches into a triangle reaching to the tip of the snout. Two pale longitudinal bands on the dorsum converge at the head outlining a large semi-rectangular marking on the back. The ventral coloration is white becoming pink under the throat with some individuals exhibiting gray spots on the throat and legs. The thighs have 2–3 transverse spots that are more irregular than in other species (Amiet 1977).

Tadpole dorsal coloration is pale brown to beige, slightly speckled. The tail axis is yellowish with large dark brown blotches and the tail fins have dark patterning but are predominantly transparent. The jaw sheaths are black (Griesbaum et al. 2019).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Cameroon

	View distribution map in BerkeleyMapper.
	View Bd and Bsal data (7 records).

This species is found in the Cameroon Volcanic Line in southwestern Cameroon (Amiet 1977; Channing and Rödel 2019). It is associated with grassy marshes and the banks of streams and lakes at elevations from 2000 - 2650 meters. Its presence has been confirmed through surveys in Mt. Bamboutos, Mt. Neshele, and Mt. Oku (Amiet 1977; Doherty-Bone and Gvoždík 2017; Tchassem et al. 2021).

Life History, Abundance, Activity, and Special Behaviors
Little is known about the life history of A. ranoides. It is suspected that the adults are diurnal (Amiet 1977; Channing and Rödel 2019).

Trends and Threats
The population trend is decreasing due to advanced deforestation, encroaching human settlements, agricultural expansion, and degradation of its aquatic habitat caused by the use of agricultural herbicides and pesticides (IUCN 2021).

Relation to Humans
Preliminary genetic studies have found two clades in the genus, a West African Clade and a Central African clade (Portik et al. 2019). Astylosternus ranoides is likely found in the Central African clade (Allen et al. unpubl. data)

References

Amiet, J.-L. (1977). ''Les Astylosternus du Cameroun (Amphibia Anura, Astylosterninae).'' Annales de la Faculté des Sciences de Yaoundé, 23/24, 99-227.

Blackburn, D. C., Hanken, J., Jenkins Jr, F. A. (2008). "Concealed weapons: erectile claws in African frogs." Biology Letters 4, 355–357. [link]

Channing, A., Rödel, M.-O. (2019). Field Guide to the Frogs and Other Amphibians of Africa. Penguin Random House South Africa, Cape Town, South Africa.

Doherty-Bone, T. M., Gvoždík, V. (2017). "The amphibians of Mount Oku, Cameroon: an updated species inventory and conservation review." ZooKeys, 643, 109–139. [link]

Griesbaum, F., Hirschfeld, M., Barej, M. F., Schmitz, A., Rohrmoser, M., Dahmen, M., Mühlberer, F., Liedtke, H.C. Gonwouo, N.L., Doumbia, J., Rödel, M. O. (2019). "Tadpoles of three western African frog genera: Astylosternus Werner, 1898, Nyctibates Boulenger, 1904, and Scotobleps Boulenger, 1900 (Amphibia, Anura, Arthroleptidae)." Zoosystematics and Evolution, 95, 133–160. [link]

IUCN SSC Amphibian Specialist Group. (2015). "Astylosternus ranoides. The IUCN Red List of Threatened Species 2015: e.T54423A16862507. https://dx.doi.org/10.2305/IUCN.UK.2015-2.RLTS.T54423A16862507.en. Accessed on 01 February 2022.

Portik DM, Bell RC, Blackburn DC, Bauer AM, Barratt CD, Branch WR, Burger M, Channing A, Colston TJ, Conradie W, Dehlin JM, Drewes RC, Ernst R, Greenbaum E, Gvozdík V, Harvey J, Hillers A, Hirschfeld M, Jongsma GFM, Kielgast J, Kouete MT, Lawson LP, Leaché AD, Loader SP, Lötters S, van der Meijden A, Menegon M, Müller S, Nagy ZT, Ofori-Boateng C, Ohler A, Papenfuss TJ, Rößler D, SinschU, Rödel MO, Veith M, Vindum J, Zassi-Boulou AG, McGuire JA (2019). ''Sexual dichromatism drives diversification within a major radiation of African amphibians.'' Systematic Biology , 68(6), 859-875. [link]

Tchassem F., A. M., Doherty-Bone, T. M., Kameni N., M. M., Tapondjou N., W. P., Tamesse, J. L., Gonwouo, L. N. (2021). "What is driving declines of montane endemic amphibians? New insights from Mount Bamboutos, Cameroon." Oryx, 55, 23–33. [link]

Species Account Citation: AmphibiaWeb 2022 Astylosternus ranoides <https://amphibiaweb.org/species/1488> University of California, Berkeley, CA, USA. Accessed Nov 22, 2024.

Citation: AmphibiaWeb. 2024. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 22 Nov 2024.

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