Description
Astylosternus montanus is a stocky bodied West African frog in which males range from 38.5–44.0 mm in snout–vent length with an average of 42.1 mm. The females are, on average, one centimeter larger than the males. This species has a rectangular head with a short snout and a rounded canthus rostralis. The tympanum to eye ratio is 66.4% with no eyelid tubercles. The posterior part of the back is covered in small granules, and females have dorso-lateral folds. The anterior limbs have tubercles at the base of each finger. Webbing on the feet varies depending on the region: in the western portion of the Bamiléké Plateau, the webbing is small and does not pass the proximal subarticular tubercle on toe V; at the center of the Bamiléké Plateau, Yoko mountain, and Adamaoua, there is moderately developed webbing that stops at the 2nd tubercle on toe V; and in the north of Adamaoua, the webbing is most extensive, passing the 1st tubercle on toe IV (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). During the breeding season, males have a double nuptial pad and well developed spines on the margins of the lower jaw (spines are 1/4 mm in diameter; Amiet 1977).

The tadpoles have a total length of ~73 mm, a body length of ~22 mm with a body length to total length ratio of 33.3 ± 1.0%. The ventral-fin-height to dorsal-fin-height ratio is 6.8%. The keratodont formula is 1:2+2/2+2:1. Anterior lip papillae are small and anterior to the angles of the mouth. The posterior lip papillae are in two rows of approximately 30 triangular papillae, slightly longer than wide with rounded tips. The rostral gap is large and the jaw sheaths are massive and serrated. The upper jaw is arched with a small medial projection and the lower jaw is V-shaped (Griesbaum et al. 2019).

On Mt. Nlonako, A. montanus was found more often on the forest floor and A. diadematus and A. perreti were found more often in streams (Plath et al. 2004; Herrmann et al. 2005).

Adult dorsal coloration is brown, beige, or olive with irregular, round black spots. There is a “tiara” design on the head similar to A. diadematus. The coloration change from dorsal to ventral is gradual with no spots or marbling on the flanks. The ventral color is pale yellow, and the throat is almost entirely covered with dark spots. Dark spots are also found on the interior of the hind limbs (Amiet 1977).

The tadpoles’ coloration is brownish, and the dorsal surface is darker than the ventral one, which is more yellow. The tail is a paler brown and has a small number of dark speckles. The fins are very pale brown and semi-transparent with a longitudinal row of small spots on the margin of the dorsal fin. The jaw sheaths are black (Griesbaum et al. 2019).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Cameroon, Nigeria

	View distribution map in BerkeleyMapper.
	View Bd and Bsal data (17 records).

This species is found in montane and submontane regions in the Cameroon Volcanic Line of Cameroon and Nigeria (Amiet 1977; Channing and Rödel 2019), where it is associated with flowing streams at elevations between 900 and 2029 meters (Amiet 1977; Channing and Rödel 2019; IUCN 2021). It is primarily found in forests but has also been noted at lesser abundance in grasslands (Amiet 1977; Channing and Rödel 2019; Tchassem Fokoua et al. 2019). Its presence has been confirmed through surveys in the following areas in Cameroon: Bamiléké Plateau, Bamoun Plateau, Adamawa Plateau, Mt Yoko, Mt. Ngorro (Amiet 1997), Mt. Mbam (Tchassem Fokoua et al. 2019), Mt. Nlonako (Plath et al. 2004), Mt. Oku (Doherty-Bone and Gvoždík, 2017) and Mt. Kupe (Hofer et al. 1999); and also in Nigeria: Obudu Plateau (Gartshore 1986) and Cross River National Park (Onadeko et al. 2010).

On Mt. Nlonako, A. montanus was found more often on the forest floor. While this species was found on the Obudu Plateau in Nigeria in the 1980’s (Gartshore, 1986), it has not been recovered in more recent surveys (Lea et al., 2005); populations reported in Reeder et al. (2011) for the Mambilla Plateau might represent A. montanus.

Life History, Abundance, Activity, and Special Behaviors
The adults are nocturnal and have two breeding seasons: one from the end of April to May, and another from November to the end of December (Amiet 1977; IUCN 2022).

Male are found calling from rock cavities and sometimes from the water (Amiet 1977; IUCN 2022). Amiet (1977) described the call as "dlouk" or "hou" and "rrra."

On Mt. Nlonako and Mt Kupe, A. montanus occurs at the same sites as A. diadematus and A. perreti. On Mt. Nlonako, A. montanus was found more often on the forest floor and A. diadematus and A. perreti were found more often in streams (Plath et al. 2004; Herrmann et al. 2005).

Trends and Threats
Threats to A. montanus are mainly habitat loss due to urbanization, forest clearing for agriculture, logging, as well as occasional human consumption (IUCN 2021).

Relation to Humans
Astylosternus montanus may be eaten in some villages although probably not at levels that constitute a major threat to this species (IUCN 2021).

Comments
Preliminary genetic studies have found two clades in the genus, a West African clade and a Central African clade. Astylosternus montanus is found in the Central African clade (Portik et al. 2019).

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]

Bogart, J. P. and Tandy, M. (1981). ''Chromosome lineages in African frogs.'' Monitore Zoologico Italiano, N.S. Supplemento, 15(5), 55-91.

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]

Gartshore, M.E. (1986). "The status of the montane herpetofauna of the Cameroon Highlands." Conservation of Cameroon montane forests. Report of the ICBP Cameroon Montane Forest Survey (Nov 1983 — Apr 1984). Stuart, S.N., eds., Chameleon Press, London.

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]

Herrmann, H.-W., Böhme, W., Herrmann, P.A., Plath, M., Schmitz, A., Solbach, M. (2005). ''African biodiversity hotspots: the amphibians of Mt. Nlonako, Cameroon.'' Salamandra, 41(1/2), 61–81.

Hofer U, Bersier L-F, Borcard D (1999). ''Spatial organization of a herpetofauna on an elevational gradient revealed by null model tests.'' Ecology, 80(3), 976–988. [link]

IUCN SSC Amphibian Specialist Group. (2017). "Astylosternus montanus." The IUCN Red List of Threatened Species 2017: e.T54419A49251040. https://dx.doi.org/10.2305/IUCN.UK.2017-2.RLTS.T54419A49251040.en. Accessed on 18 January 2022.

Lea, J. M., Luiselli, L., Politano, E. (2005). "Are there shifts in amphibian faunal composition in Nigerian landscapes undergoing long-term degradation? A case study from a montane environment." Revue d'écologie, 60, 65–76. [link]

Onadeko, A. B., Rodel, M. O., Egonmwan, R. I., Saliu, J. K. (2010). "Herpetological surveys of south-western and south-eastern regions of Nigeria." Zoologist, 8, 34–43. [link]

Plath M, Solbach M, Herrmann H-W (2004). ''Anuran habitat selection and temporal partitioning in a montane and submontane rainforest in southwestern Cameroon – first results.'' Salamandra (Frankf), 40, 239-260. [link]

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 Fokoua, A. M., Gonwouo, L. N., Tamesse, J. L., Doherty-Bone, T. M. (2019). "Value of forest remnants for montane amphibians on the livestock grazed Mount Mbam, Cameroon." Amphibian & Reptile Conservation, 13, 68–81. [link]

Species Account Citation: AmphibiaWeb 2022 Astylosternus montanus <https://amphibiaweb.org/species/1484> University of California, Berkeley, CA, USA. Accessed Nov 21, 2024.

Citation: AmphibiaWeb. 2024. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 21 Nov 2024.

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