Microhyla

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. 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).

Taxonomy
In 2021, nine species of Microhyla were moved to Nanohyla on the basis of morphological and phylogenetic differences. Microhyla pulverata was found to be a junior synonym of Nanohyla marmorata based on phylogenetic evidence.

Diagnosis
According to Seshadri et al. (2016), 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. 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. However, ascertaining the phylogenetic relationship of frogs within Microhyla has been difficult as many species are not monophyletic.

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.

Species
The following species are recognised in the genus Microhyla:

In central Vietnam, several new species of Microhyla have been described in the 2000s:
 * Microhyla darevskii: Mount Ngọc Linh, Kon Tum Province
 * Microhyla minuta: Đồng Nai Province
 * Microhyla pineticola: Lâm Đồng Province and Đắk Lắk Province

Several new species of Microhyla have been described since 2018.

Phylogeny
The following phylogeny of the genus Microhyla is from Khatiwada, et al. (2017). 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.)