Description
Female: 22-28 mm, Male: 19-24 mm. Dorsum black, generally with small yellow blotches along the flanks. Belly and chest black with red blotches and/or yellow spots. Interdigital web poorly developed. Sexual dimorphism is not evident. This species could be easily confused with Melanophryniscus atroluteus.

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Brazil, Uruguay

	View distribution map in BerkeleyMapper.
	View Bd and Bsal data (2 records).

The species inhabits coastal areas with dunes and sandy soils in the Uruguayan Atlantic shore region. Mainly southern Uruguay (only one locality known in Southern Brazil).

Life History, Abundance, Activity, and Special Behaviors
The diet of this toad consists of small arthropods (little beetles, collembolans, aphids, ants, acari). These diurnal toads are explosive breeders. Reproduction occurs during warm days following rains. As in most of the species belonging to this genus, the nuptial call has two components (a repeated whistle and a train of vibrations). During amplexus males massage females; oviposition is made in several inmersions. This species exhibits a defensive behavior named "Unkenreflex" (it shows the red belly, palms and soils to the attacker). The skin of these toads have alkaloids (like pumiliotoxins).

Trends and Threats
M. atroluteus is a declining species in Uruguay. Malformed specimens and albino larvae have been reported. Habitat loss seems to be the main cause of declines.

Possible reasons for amphibian decline

General habitat alteration and loss
Urbanization
Habitat fragmentation
Local pesticides, fertilizers, and pollutants

References

Achaval, F., and Olmos, A. (2003). Anfibios y reptiles del Uruguay Ed. Graphis. Serie Fauna N°, Montevideo, Uruguay.

Garrido-Yrigaray, R. R. (1989). ''Descripción de la larva de Melanophrynsicus stelzneri montevidensis (Philippi, 1902) (Anura: Bufonidae).'' Boletín de la Sociedad Zoológica del Uruguay (2a. Época), 5, 1-8.

Klappenbach, M. A., and Langone, J. A. (1992). ''Lista sistemática y sinonímica de los anfibios del Uruguay con comentarios y notas sobre su distribución.'' Anales del Museo Nacional de Historia Natural de Montevideo (2a Serie), 8, 163-222.

Klappenbach, M. A., and Miranda, O. B. (1969). Anfibios y Reptiles. Nuestra Tierra, Montevideo, Uruguay.

Kolenc, F. (1987). ''Anuros del género Melanophryniscus en la República Oriental del Uruguay.'' Aquarama, 5(30), 16-21.

Kwet, A., Maneyro, R., Zillikens, A., and Mebs, D. (2005). ''Advertisement calls of Melanophryniscus dorsalis (Mertens, 1933) and M. montevidensis (Philippi, 1902), two parapatric species from southern Brazil and Uruguay, with comments on morphological variation in the Melanophryniscus stelzneri group (Anura: Bufonidae).'' Salamandra, 41(1/2), 1-18.

Langone, J. A. (1994). Ranas y sapos del Uruguay (reconocimientos y aspectos biológicos). Museo Damaso Antonio Larrañaga 5, Serie de Divulgación

Maneyro, R., Forni, F., and Santos, M. (1995). Anfibios del Departamento de Rocha. Serie Divulgación Técnica 1 (PROBIDES), Rocha, Uruguay.

Maneyro, R., and Achaval, F. (2004). ''Melanophryniscus montevidensis (Darwin’s Toad). Albino Larvae.'' Herpetological Review, 35(3), 261.

Maneyro, R., and Langone, J. A. (2001). ''Categorización de los anfibios del Uruguay.'' Cuadernos de Herpetología, 15(2), 107-118.

Mebs, D., Pogoda, W., Maneyro, R. and Kwet, A (2005). ''Studies on the poisonous secretion of individual red bellied toads, Melanophryniscus montevidensis (Anura, Bufonidae), from Uruguay.'' Toxicon, 46, 641-650.

Núñez, D., Maneyro, R., Langone, J. A. and De Sá, R. O. (2004). ''Distribución geográfica de la fauna de anfibios del Uruguay.'' Smithsonian Herpetological Information Series, 134, 1-34.

Prigioni, C., and Garrido, R. R. (1989). ''Algunas observaciones sobre la reproducción de Melanophryniscus stelzneri montevidensis (Anura, Bufonidae).'' Boletín de la Sociedad Zoológica del Uruguay (Actas de las II Jornadas de Zoología del Uruguay), 5, 13-14.

Species Account Citation: AmphibiaWeb 2006 Melanophryniscus montevidensis <https://amphibiaweb.org/species/345> University of California, Berkeley, CA, USA. Accessed Nov 12, 2024.

Citation: AmphibiaWeb. 2024. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 12 Nov 2024.

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