Microhyla, commonly known as the rice frogs or narrow-mouthed frogs, is a genus of frogs in the family Microhylidae. It consists of 42 species of diminutive frogs.[1] Members of this genus are widespread from Ryukyu Is. in Japan, and throughout South-east Asia, (China, Sumatra, Java, Bali, Borneo, India and Sri Lanka).[2]
Taxonomy
In 2021, nine species of Microhyla were moved to Nanohyla on the basis of morphological and phylogenetic differences.[1]Microhyla pulverata was found to be a junior synonym of Nanohyla marmorata based on phylogenetic evidence.[3]
Diagnosis
According to Seshadri et al. (2016),[4] this genus can be diagnosed using the following set of criteria: Adult frogs are of small size; pupil circular; skin on dorsum smooth; lateral side of body with markings from back of eye to vent; supratympanic fold present in adults; paratoid glands are absent, fingers without webbing, finger tips may or may not be dilated; oval tongue, its margin is entire and free at the base; the diameter of eye is smaller than snout; a thin layer of skin hides the tympanum; tubercles on hand distinct; distinct oval shaped inner metatarsal tubercle and rounded outer metatarsal tubercle; webbing in feet, rudimentary.
Evolutionary relationships
The genus Microhyla is closely related to Glyphoglossus within the family Microhylidae.[2][5] Members of the genus Microhyla began diversifying from the most common ancestor around 45 million years ago and this resulted in forming Metaphrynella and Microhyla.[5] However, ascertaining the phylogenetic relationship of frogs within Microhyla has been difficult as many species are not monophyletic.[6]
A 2021 study on the relationship between Microhyla and Glyphoglossus found that nine species within Microhyla actually belong to a separate lineage. They have been subsequently moved to the new genus, Nanohyla.[1]
Species
The following species are recognised in the genus Microhyla:[2][4][7]
Several new species of Microhyla have been described since 2018.
Phylogeny
The following phylogeny of the genus Microhyla is from Khatiwada, et al. (2017).[12] 27 species are listed, including various newly described species from South Asia.
(Note: the chart below includes some species that have since been moved to Nanohyla including N. annectens and N. perparva.)
^ abcFrost, Darrel R. 2016. Amphibian Species of the World: an Online Reference. Version 6.0 (Date of access). Electronic Database accessible at http://research.amnh.org/herpetology/amphibia/index.html. American Museum of Natural History, New York, USA.
^ abcPoyarkov Jr NA, Vassilieva AB, Orlov NL, Galoyan EA, Dao TT, Le DT, et al. (2014). "Taxonomy and distribution of narrow-mouth frogs of the genus Microhyla Tschudi, 1838 (Anura: Microhylidae) from Vietnam with descriptions of five new species". Russian Journal of Herpetology. 21: 89โ148.
^Wijayathilaka N, Garg S, Senevirathne G, Karunarathna N, Biju SD, Meegaskumbura M (January 2016). "A new species of Microhyla (Anura: Microhylidae) from Sri Lanka: an integrative taxonomic approach". Zootaxa. 4066 (3): 331โ42. doi:10.11646/zootaxa.4066.3.9. PMID27395556.
^Matsui M, Hamidy A, Eto K (2013). "Description of a new species of Microhyla from Bali, Indonesia (Amphibia, Anura)". Zootaxa. 3670 (4): 579โ90. doi:10.11646/zootaxa.3670.4.9. PMID26438961.
