Family- Microhylidae (Narrow-mouth Frogs)

432+ species are known from the world and they are categorizrd in to eleven subfamilies (Asterophrynae, Brevicepitinae, Cophylinae, Ceratobatrachinae, Dyscophinae, Gastrophryninae, Geniyophryninae, Melanobatrachidae, Microhilinae, Phrynomerininae, Scaphiophryninae). Microhylids are disitributed throughout the world in warm temperate and tropical regions.  They are usually small frogs and grows up to a maximum of 100mm. They have several od shapes ranging from  squat and small headed globular  to toadlike  and to areboreal frogs with expanded digits. Their pupils  are horizontal or round. Reproduction can be direct and indirect and amplexus is axillary. Their tadpoles lack keratinous beaks or denticles.
Microhylidae in Sri Lanka
All the species of Microhylidae in Sri Lanka belong to the subfamily Microhylinae. Ten species are known from Sri Lanka that belongs to four genera (Kaloula, Microhyla, Ramanella, Uperedon). Five species are endemic to Sri Lanka. All the species of Microhylids in Sri Lanka show indirect development and thier free living tadpoles lack keratinous mouth parts.   
Genus- Kaloula Gray, 1831
Only one species of Kaloula recorded in Sri Lanka (K. taprobanica) . It is a common species mainly seen in the lowlands of Sri Lanka but occasionally seen in the hills upto an elevation of 500m a.s.l. They have a globular shape body with a narrow head region. The adults reach a snout to vent length around 45mm. These frogs possess triangular shaped sticky finger tips that aids them in climbing. They are highly capable of climbing and many have been observed climbing trees and walls. When disturbed or handled they inflate their body and also release a sticky substance from the cloacca.    
Species of Kaluola in Sri Lanka
Kaloula taprobanica Parker, 1934
Genus- Microhyla Tschudi, 1838
Four species are known from Sri Lanka. Three are endemic to Sri Lanka. They are small frogs that grows upto a maximum of 35mm from snout to vent. Their tadpoles are filter feeders and feed on dissolved particulate matter dispersed in the water column. M. karunarathei is an endemic and a rare species of frog restricted in distribution in the vicinity of Rakwana hills in Sri Lanka. M. zeyalnica is an endemic  montane species distributed in the elevations above 1500m above m.s.l. M. ornata and M. mihintalei (formally M. rubra) are common species distributed in the lowlands up to an elevation of 600m above m.s.l.
Species of Microhyla in Sri Lanka
Microhyla karunaratnei Fernando and Siriwardhane, 1996E
Microhyla ornata (Dumeril and Bibron, 1841)
Microhyla mihintalei Wijayathilaka, Garg, Senevirathne, Karunarathna, Biju and Meegaskumbura, 2016E
Microhyla zeylanica Parker and Osman-Hill, 1949E
Genus- Ramanella Rao and Ramanna, 1925
Four species are recorded from Sri lanka. Three are endemic to Sri Lanka. They are small frogs growing to a maximum snout to vent length of 35 mm. They have a flat body with a narrow head region.Their tadpoles are filter feeders and feed on dissolved particulate matter dispersed in the water column. They are capable of climbing trees and vertical walls. These frogs have triangular shaped finger tips. R. nagaoi and R. obscura are known to lay eggs in water collected in tree holes. R. obscura is known to feed on ants and termites in captivity.  R. nagaoi is retricted to the lowland rainforests of the southern province of sri Lanka. R. obscura is distributed in throughout the wet zone of Sri Lanka up to an elevation of 1000m above m.s.l. R. variegata is found in the lowlands of Sri Lanka upto an elevation of 500m above m.s.l. R. palmata is a montane species restricted to the regions above 1500m above m.s.l.
Species of Ramanella in Sri Lanka
Ramanella nagaoi Manamendra-Arachchi and Pethiyagoda, 2001E
Ramanella obscura (Gunther, 1864)E
Ramanella variegata  (Stoliczka, 1872)
Ramanella palmata Parker, 1934E
Genus- Uperodon Dumeril and Bibron, 1841
Only two species are known from this genus. One species (Uperodon systoma) is known from Sri Lanka. U. systoma is also seen in India, Pakistan and Nepal. Species of Uperodon has a smooth moist skin and the body resembles a water filled balloon. They have a stout body with a narrow mouth region. This appearance has earned U. systoma the name "Marbled Balloon Frog'.This burrowing species of Microhylid frog is distributed in the lowland dry and intermediate zones of Sri Lanka. Yet a common species but rarely seen due to its' burrowing and nocturnal habits. U. systoma grows up to a snout to vent length of 60mm. They can be seen more often during the rainy season in the dry zone. It is known to feed on termites.

Species of Uperodon in Sri Lanka

Uperodon systoma  (Schneider, 1799)  
Abreviations in superscript
E- Endemic species, Ex- Extinct species, Cr- Critically Endangered species, En- Endangered species