Species Description: Rittmeyer EN, Allison A, Gruender MC, Thompson DK, Austin CC 2012 Ecological guild evolution and the discovery of the world's smallest vertebrate. PLoS One 7:e29797
From other species outside of the genus, P. amanuensis can be differentiated by having fewer pre-sacral vertebrate (7 instead of 8). Like other miniaturized species, P. amanuensis also has reduced ossification of some cranial elements and reduction in phalangeal and digital structures of the hands and feet. Paedophryne amanuensis is morphologically distinguished from other members of the genus, P. kathismalphlox, P. oyatabu and P. swiftorum, through its extremely small snout-vent length of 7.0 - 8.0 mm and its moderately long legs with a tibia length to snout-vent length ratio ranging from 0.478 - 0.507. It is distinguished further from P. oyatabu and P. swiftorum by having a longer, narrower head, and from P. kathismaphlox by having a broader, shorter head. Lastly, P. amauensis can be further differentiated from P. swiftorum through its higher dominant frequency call ranging from approximately 8400 - 9400 HZ and consists of single notes rather than eight paired notes (Rittmeyer et al. 2012).
The dorsal side of P. amanuensis is dark brown with some tan to rusty-brown blotches. The lateral and ventral surface of the frog is ranges from dark brown to slate grey with irregular bluish-white speckles (Rittmeyer et al. 2012).
Distribution and Habitat
Country distribution from AmphibiaWeb's database: Papua New Guinea
Life History, Abundance, Activity, and Special Behaviors
These frogs can be primarily heard calling at dawn and dusk from the leaf litter of primary forests. Their calls consists of a continuous series of high-pitched notes that last from 2 - 14 ms, are produced at a rate of 1.5 notes per second, and have a dominant frequency ranging from 8400 - 9400 Hz. The calls last for 1 – 3 minutes with a brief rest of 3.3 – 40.8 seconds before starting again. One male produced 355 calls in four groups over 5.5 minutes. These calls sound similarly to those created from a stridulating insect (Rittmeyer et al. 2012).
Paedophryne amanuensis feed on minute invertebrate species, such as acarians and collembolans. Because of their small size and relatively common abundance, P. amanuensis are likely an important member of the tropical wet-forest ecosystems (Rittmeyer et al. 2012)
As a small species, P. amanuensis is likely more susceptible to invertebrate predation, which may may explain its absence from aquatic habitats and tendency to inhabit upland habitat where there is less invertebrate diversity than the lowlands (Rittmeyer et al. 2012).
Based on Maximum Likelihood analysis of 12S and 16S ribosomal RNA gene, P. amanuensis is sister to P. swiftorum. However, there are deep divergences between Padeophyrne species, with uncorrected p-distances of greater or equal to 0.102, suggesting that the small size of the genus arose from early radiation of microhylid frogs in New Guinea. Genetic analysis also suggests that the genus Paedophryne has a close relationship with Barygenys exsul and Cophixalus balbus (Rittmeyer et al. 2012).
The species epithet “amauensis” refers to Amau Village, which is located near where the frog was discovered (Rittmeyer et al. 2012).
Paedophryne amauensis took the title for the world’s smallest vertebrate from Paedocypris progenetica, an Indonesian fish that measures at 7.9 mm (Rittmeyer et al. 2012).
The ecological similarities of the genus Paedophyrne suggests an independent origin of minute frogs that adds evidence to an ecological niche that miniaturized frogs occupies rather than their being evolutionary outliers (Rittmeyer et al. 2012).
The discovery of P. amauensis, along with its sister species P. swiftorum expands the range of the genus Paedophyrne westward (Rittmeyer et al. 2012).
Rittmeyer, E. N., Alison, A., Grüdler, M. C., Thompson, D. K., Austin, C. C. (2012). ''Ecological guild evolution and the discovery of the world’s smallest vertebrate.'' PLoS ONE, 7(1), e29797. [link]
Written by Spencer Wong (spencerwong AT utexas.edu), University of Texas, Austin
First submitted 2019-05-13
Edited by Ann T. Chang (2019-05-13)
Species Account Citation: AmphibiaWeb 2019 Paedophryne amauensis <http://amphibiaweb.org/species/7760> University of California, Berkeley, CA, USA. Accessed Jul 1, 2020.
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Citation: AmphibiaWeb. 2020. <http://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 1 Jul 2020.
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