Mantidactylus radaka Rancilhac, Bruy, Scherz, Pereira, Preick, Straube, Lyra, Ohler, Streicher, Andreone, Crottini, Hutter, Randrianantoandro, Rakotoarison, Glaw, Hofreiter & Vences, 2020
Madagascar Giant Stream Frog
|Species Description: Rancihac L, Bruy T, Scherz MD, Pereira EA, Preick M, Straube N, Lyra ML, Ohler A, Streicher JW, Andreone F, Crottini A, Hutter CR, Randrianantlandro JC, Rakotoarison A, Glaw F, Hofreiter M, Vences M 2020 Target-enriched DNA sequencing from historical type material enables a partial revision of the Madagascar giant stream frogs (genus Mantidactylus). Journal of Natural History 54:87-118.|
There are two similar species within the same genus: M. guttulatus and M. grandidieri. Mantidactylus radaka can be differentiated from M. guttulatus by having a longer relative hind limb length (hind limb to snout-vent length ratio of 1.46 - 1.60 versus 1.28 - 1.43). They also have larger and ovoid femoral glands in males (versus round ones in M. guttulatus and M. grandidieri) and indistinct femoral glands in females (versus always recognizable in M. guttulatus and M. grandidieri). In life, M. radaka typically has a hidden and smaller tympanum when compared to the tympanum of these other two species. Lastly, Mantidactylus radaka individuals in Besariaka have been observed to favor running water while M. grandidieri appears to prefer stream banks (Rancilhac et al. 2020).
In preservative, the dorsal coloration is brown with tiny yellow-ish dots on the warts. Their venter is beige with indistinct mottling on the throat. In life, the coloration is similar but with larger yellowish dots and uniformly green-brown irises. They also have light tips on the inner three fingers. These frogs lack a dorsolateral color border as well as a distinct frenal stripe. They are also characterized by the absence of large yellowish markings in the inguinal region or between coloration of flanks and belly (Rancilhac et al. 2020).
There is no significant difference between the tympanum diameter of males and females. In terms of femoral pores, females in life have tiny black patches whereas females in preservative lack them altogether. Young males typically have externally and internally distinct femoral pores that are ovoid. Some females also have a very dark throat coloration (Rancilhac et al. 2020).
Distribution and Habitat
Country distribution from AmphibiaWeb's database: Madagascar
Life History, Abundance, Activity, and Special Behaviors
Observations on M. guttulatus recorded by Schulze et al. (2016) are believed to actually be for M. radaka. As such, the reproduction period for M. radaka is at the beginning of the warm-rainy season and peaks towards the beginning of the cool-dry season.
They have been observed to lay very large clutches of eggs (Rancilhac et al. 2020, Razafison 2020).
Trends and Threats
Relation to Humans
Possible reasons for amphibian decline
General habitat alteration and loss
The Maximum Likelihood analysis conducted on 16S mtDNA and Rag-1 nDNA sequences indicated that M. guttulatus is the sister taxon to the clade composed of M. radaka and M. grandidieri. Four other undescribed clades were also identified and were placed basally to the three named Mantidactylus species (Rancilhac et al. 2020).
The species epithet, “radaka,” comes from the Malagasy word for large frogs in reference to the size of the species and other members of the genus (Rancilhac et al. 2020).
Rancilhac, L., Bruy, T., Scherz, M. D., Pereira, E. A., Preick, M., Straube, N., Lyra, M. L., Ohler, A., Streicher, J. W., Andreone, F., Crottini, A., Hutter, C. R., Randrianantoandro, C., Rakotoarison, A., Glaw, F., Hofreiter, M., Vences, M. (2020). "Target-enriched DNA sequencing from historical type material enables a partial revision of the Madagascar giant stream frogs (genus Mantidactylus). Journal of Natural History, 54(1-4), 87-118. [link]
Razafison, R. (2020). “Madagascar giant frog is a new species, but also a deep-fried delicacy.” Mongabay Environmental News, 1 Sept. 2020. https://news.mongabay.com/2020/09/madagascar-giant-frog-is-a-new-species-but-also-a-deep-fried-delicacy/. Accessed in April 2022 [link]
Schulze, A., Randrianiaina, R.-D., Perl, B., Glaw, F., Vences M. (2016). “The unexpectedly dull tadpole of Madagascar’s largest frog, Mantidactylus guttulatus.” Acta Herpetologica, 11(2), 119-125. [link]
Originally submitted by: Mariam Alsaid (2023-03-16)
Description by: Mariam Alsaid (updated 2023-03-16)
Distribution by: Mariam Alsaid (updated 2023-03-16)
Life history by: Mariam Alsaid (updated 2023-03-16)
Larva by: Mariam Alsaid (updated 2023-03-16)
Trends and threats by: Mariam Alsaid (updated 2023-03-16)
Relation to humans by: Mariam Alsaid (updated 2023-03-16)
Comments by: Mariam Alsaid (updated 2023-03-16)
Edited by: Ann T. Chang (2023-03-16)
Species Account Citation: AmphibiaWeb 2023 Mantidactylus radaka: Madagascar Giant Stream Frog <https://amphibiaweb.org/species/9313> University of California, Berkeley, CA, USA. Accessed Sep 22, 2023.
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Citation: AmphibiaWeb. 2023. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 22 Sep 2023.
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