Brown frog (Rana sauteri)

Description

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Brown frog fact file

• Description
• Biology
• Range
• Habitat
• Status
• Threats
• Conservation
• Find out more
• Glossary
• References
• Print factsheet

Brown frog description

Unique among the brown frogs of the genus Rana, the larvae of Rana sauteri have a distinctive appearance and behaviour ⁽³⁾. First described by Boulenger in 1909, Rana sauteri is a small-sized, brown frog ^{(4) (5)}. Due to their close morphological similarities, brown frogs are notoriously difficult to distinguish ⁽⁶⁾. However, unlike most brown frogs, the digit tips of Rana sauteri have discs and horizontal grooves, an adaptation to life in fast-running water ⁽³⁾, earning its alternative common name of the Taiwan groove-toed frog ⁽⁷⁾.

The female Rana sauteri tends to be significantly larger than the male ⁽⁸⁾. The Rana sauteri tadpole is highly pigmented, has a flat body, large mouthparts, an abdominal sucker and a stout tail ^{(3) (9)}.

Size

Male snout-vent length: 42 mm ⁽²⁾

Female snout-vent length: 52 mm ⁽²⁾

Brown frog biology

Rana sauteri is known to breed between October and April ⁽³⁾. The mature adult generally joins large breeding aggregations in fast-flowing streams, but has also been found in still-water pools. Eggs are usually found under submerged rocks at depths of 10 to 15 centimetres ⁽⁸⁾.

Rana sauteri feeds mainly on arthropods, especially insects. This species shows a preference for certain prey items and does not forage randomly ⁽¹²⁾.

The Rana sauteri tadpole is extremely specialised for survival in fast-flowing water. Its morphology is unusual among brown frogs because it has a large abdominal sucker which allows it to cling to rocks in streams. It feeds on algae growing on the surface of rocks ⁽³⁾.

Brown frog range

Rana sauteri is endemic to western Taiwan, where it can be found in lowland areas between elevations of 170 and 500 metres above sea level ⁽¹⁾. High-altitude populations of the brown frog in this region are now considered a separate species, Rana multidenticulata ⁽¹⁰⁾.

Brown frog habitat

Rana sauteri inhabits low-altitude hill forests and nearby small streams ⁽¹¹⁾. During winter, Rana sauteri is usually found under stones in small streams and in hollows under banks. In summer, it is often found on the forest floor rather than in water ⁽³⁾.

Brown frog status

Rana sauteri is classified as Endangered (EN) on the IUCN Red List ⁽¹⁾

Brown frog threats

Currently this species is relatively common, but its numbers are declining. It is primarily threatened by habitat loss due to agriculture and industry ⁽¹¹⁾. Furthermore, Rana sauteri is also potentially threatened by the chytrid fungus responsible for chytridiomycosis, an emerging infectious disease which is detrimental to amphibian species ⁽¹³⁾.

Brown frog conservation

Rana sauteri has not been recorded from any protected areas. Improved protection of its low-altitude forest habitat is required in order to conserve this species ⁽¹⁾.

Find out more

Learn more about Rana sauteri:

• AmphibiaWeb - Rana sauteri:
  http://amphibiaweb.org/cgi/amphib_query?where-genus=Rana&where-species=sauteri

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This species information was authored as part of the ARKive and Universities Scheme.

Glossary

Algae

Simple plants that lack roots, stems and leaves but contain the green pigment chlorophyll. Most occur in marine and freshwater habitats.

Arthropods

A major grouping of animals that includes crustaceans, insects and arachnids. All arthropods have paired jointed limbs and a hard external skeleton (exoskeleton).

Endemic

A species or taxonomic group that is only found in one particular country or geographic area.

Genus

A category used in taxonomy, which is below ‘family’ and above ‘species’. A genus tends to contain species that have characteristics in common. The genus forms the first part of a ‘binomial’ Latin species name; the second part is the specific name.

Larva

Immature stage in an animal’s lifecycle, after it hatches from an egg and before it changes into the adult form. Larvae are typically very different in appearance to adults; they are able to feed and move around but are usually unable to reproduce.

Morphological

Referring to the visible or measurable characteristics of an organism.

References

1. IUCN Red List (November, 2011)
   http://www.iucnredlist.org/
2. Huang, W.S., Cheng, Y.S. and Tu, H.Y. (2004) Reproductive patterns of two sympatric ranid frogs, Rana latouchii and R .sauteri, with comments on Anuran breeding seasons in Taiwan. Collection and Research, 17: 1-10.
3. Kuramoto, M., Wang, C.S. and Yu, H.T. (1984) Breeding, larval morphology and experimental hybridization of Taiwanese brown frogs, Rana longicrus and R. sauteri. Journal of Herpetology, 18: 387-395.
4. Boulenger, G.A. (1909) Descriptions of four new frogs and a new snake discovered by Mr. H. Sauter in Formosa. Annals and Magazine of Natural History, 8: 492-495.
5. Lai, S.J., Kam, Y.C., Hsu, F.H. and Lin, Y.S. (2002) Elevational effects on the growth and development of tadpoles of Sauter’s frog Rana sauteri. Acta Zoologica Taiwanica, 13: 11-20.
6. Che, J., Pang, J., Zhao, E., Matsui, M. and Zhang, Y. (2007) Phylogenetic relationships of the Chinese brown frogs (genus Rana) inferred from partial mitochondrial 12S and 16S rRNA gene sequences. Zoological Science, 24: 71-80.
7. Dubois, A. (1992) Notes sur la classification des Ranidae (Amphibiens Anoures). Bulletin mensuel de la Société linnéenne de Lyon, 61: 305-352.
8. Lai, S.J., Kam, Y.C. and Lin, Y.S. (2003) Elevational variation in reproductive and life history traits of Sauter’s frog Rana sauteri Boulenger, 1909 in Taiwan. Zoological Studies, 42: 193-202. 
9. Matsui, T. and Matsui, M. (1990) A new brown frog (genus Rana) from Honshu, Japan. Herpetologica, 46: 78-85.
10. Chou, W.H. and Lin, J.Y. (1997) Geographical variations of Rana sauteri (Anura: Ranidae) in Taiwan. Zoological Studies, 36: 201-22.
11. Stuart, S.N., Hoffmann, M., Chanson, J.S., Cox, N.A., Berridge, R.J., Ramani, P. and Young, B.E. (Eds.) (2008) Threatened Amphibians of the World. Lynx Edicions, Barcelona, Spain; IUCN, Gland, Switzerland; and Conservation International, Arlington, Virginia, USA.
12. Jhang, W.H. and Wu, S.H. (2009) Food habits of three stream-living frogs (Bufo bankorensis, Odorrana swinhoana, and Rana sauteri) in the Wu-lin area. Ph.D. Thesis, Department of Life Science, National Chung Hsing University Institutional Repository.
13. Pounds, J.A., Bustamante, M.R. et al. (2006) Widespread amphibian extinctions from epidemic disease driven by global warming. Nature, 439: 161-167.