''Microhyla borneensis'' (

junior synonym In taxonomy, the scientific classification of living organisms, a synonym is an alternative scientific name for the accepted scientific name of a taxon. The botanical and zoological codes of nomenclature treat the concept of synonymy differently. ...

''Microhyla nepenthicola''), also known as the Matang narrow-mouthed frog, is a species of

microhylid The Microhylidae, commonly known as narrow-mouthed frogs, are a geographically widespread family of frogs. The 683 species are in 57 genera and 11 subfamilies. Evolution A molecular phylogenetic study by van der Meijden, et al. (2007) has estima ...

frog A frog is any member of a diverse and largely semiaquatic group of short-bodied, tailless amphibian vertebrates composing the order (biology), order Anura (coming from the Ancient Greek , literally 'without tail'). Frog species with rough ski ...

found in the Matang Range in

Sarawak Sarawak ( , ) is a States and federal territories of Malaysia, state of Malaysia. It is the largest among the 13 states, with an area almost equal to that of Peninsular Malaysia. Sarawak is located in East Malaysia in northwest Borneo, and is ...

Borneo Borneo () is the List of islands by area, third-largest island in the world, with an area of , and population of 23,053,723 (2020 national censuses). Situated at the geographic centre of Maritime Southeast Asia, it is one of the Greater Sunda ...

. It was once the smallest known frog from the

Old World The "Old World" () is a term for Afro-Eurasia coined by Europeans after 1493, when they became aware of the existence of the Americas. It is used to contrast the continents of Africa, Europe, and Asia in the Eastern Hemisphere, previously ...

(since 2012, the record holder has been ''

Paedophryne amauensis ''Paedophryne amauensis'', also known as the New Guinea Amau frog, is a species of microhylid frog endemic to eastern Papua New Guinea. At in snout-to-vent length, it was once considered the world's smallest known vertebrate. (See also Ecolo ...

'' from New Guinea). Adult males of this species generally have a

snout–vent length Snout–vent length (SVL) is a morphometric measurement taken in herpetology from the tip of the snout to the most posterior opening of the cloacal slit (vent)."direct line distance from tip of snout to posterior margin of vent" It is the mos ...

(SVL) in the range of , but may reach a maximum of . Adult females have an SVL of . The

tadpole A tadpole or polliwog (also spelled pollywog) is the Larva, larval stage in the biological life cycle of an amphibian. Most tadpoles are fully Aquatic animal, aquatic, though some species of amphibians have tadpoles that are terrestrial animal, ...

s measure just 3 mm.

Discovery

''Microhyla borneensis'' was first described by

Hampton Wildman Parker Hampton Wildman Parker, CBE (5 July 1897 – 2 September 1968) was an English zoologist. Parker graduated from Cambridge in 1923 with degrees in botany, zoology, and chemistry. Within the same year, he joined the staff of the British Museum (Natu ...

in 1928. Frogs of the species that was eventually described as ''Microhyla nepenthicola'' had been known for at least 100 years prior to its description in 2010. However, scientists had always assumed that the frogs were juveniles of another species. Researchers Indraneil Das and Alexander Haas recognized that they were actually adults when they heard the frogs calling in

Kubah National Park The Kubah National Park () is a national park in Kuching Division, Sarawak, Malaysia, located at 20 km from the city centre. Wild animals are hidden deep in the rainforest here, and some of the species that live here are bearded pigs, mouse deer ...

, since only adult frogs make calls. Adult males call from the pitcher plants at dusk. However, in 2011 it was shown that ''M. borneensis'' and ''M. nepenthicola'' are the same species. What was until that point commonly known as ''Microhyla borneensis'' was another species, newly described as '' Microhyla malang''. The smallest known Old World frog species prior to the description of ''Microhyla nepenthicola'' were '' Stumpffia pygmaea'' and '' Stumpffia tridactyla'': ''S. pygmaea'' with an SVL of 10–12.5 mm; ''S. tridactyla'' with an SVL of 8.6–12 mm. * "''Stumpffia pygmaea'' Vences & Glaw, 1991" p. 310 * "''Stumpffia tridactyla'' Guibé, 1975" pp. 336–338

Description

''Microhyla borneensis'' is a very small species with a

of about for females and around two thirds of this for males. It has a broadly triangular body that is flattened dorso-ventrally. The snout is obtusely pointed, the eyes are small and have round pupils and there are no visible

tympani Timpani (; ) or kettledrums (also informally called timps) are musical instruments in the percussion family. A type of drum categorised as a hemispherical drum, they consist of a membrane called a head stretched over a large bowl traditionally ...

. The skin on the dorsal surface may be smooth or bear tubercles and that of the ventral surface is always smooth. The limbs are short. The hands are unwebbed and the outer digits are spatulate. The digits of the feet are partially webbed. ''M. borneensis'' has less webbing on its feet than most frogs, which may be beneficial when trying to climb the sides of the pitcher plants, which can be slippery. The dorsal surface of this frog is reddish-brown, the throat is mottled brown and the ventral surface is pale.

Distribution and habitat

''Microhyla borneensis'' is known from the Matang Range in

, Borneo, but it is presumably widespread in suitable habitats in the lowlands of northern Borneo. ''M. borneensis'' is found near

Mount Serapi Mount is often used as part of the name of specific mountains, e.g. Mount Everest. Mount or Mounts may also refer to: Places * Mount, Cornwall, a village in Warleggan parish, England * Mount, Perranzabuloe, a hamlet in Perranzabuloe parish, C ...

, Sarawak, Borneo. It spends much of its life cycle in the traps of the

pitcher plant Pitcher plants are carnivorous plants known as pitfall traps—a prey-trapping mechanism featuring a deep cavity filled with digestive liquid. The traps of pitcher plant are considered to be "true" pitcher plants and are formed by specialized ...

Nepenthes ampullaria ''Nepenthes ampullaria'' (; Latin ''ampulla'' meaning "flask") is a very distinctive and widespread species of tropical pitcher plant, present in Borneo, the Maluku Islands, New Guinea, Peninsular Malaysia, Singapore, Sumatra, and Thailand.McPhe ...

'', after which it is named. It is therefore considered a nepenthebiont. This is not particularly unusual; in fact, it shares this environment with a species of

crab spider The Thomisidae are a family of spiders, including about 170 genera and over 2,100 species. The common name crab spider is often linked to species in this family, but is also applied loosely to many other families of spiders. Many members of thi ...

, ''

Henriksenia labuanica ''Henriksenia labuanica'' is a species of spider in the family Thomisidae, found in Malaysia (Borneo). Taxonomy The species was first named by Reginald Innes Pocock in 1898 as ''Misumena nepenthicola''; however, he did not give a diagnosis, so ...

'', which is also commonly found in ''

Nepenthes ''Nepenthes'' ( ) is a genus of carnivorous plants, also known as tropical pitcher plants, or monkey cups, in the monotypic family Nepenthaceae. The genus includes about 170 species, and numerous natural and many cultivated hybrids. They are m ...

'' pitchers. This spider's former binomen, ''Misumenops nepenthicola'', and that of the related species of Singapore, ''

Henriksenia nepenthicola ''Henriksenia nepenthicola'', synonym ''Misumenops nepenthicola'', is a species of crab spider. It is native to Singapore. It lives inside the pitchers of a number of lowland ''Nepenthes'' pitcher plants. As such, it is classified as a nepenthep ...

'', had the

specific epithet In Taxonomy (biology), taxonomy, binomial nomenclature ("two-term naming system"), also called binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin gramm ...

applied for this reason.

Reproduction

''Microhyla borneensis'' breeds in the water-filled pitchers of ''

'', a pitcher plant that is a feature of the floor of the Borneo rainforest. Multiple clutches may be laid in the same pitcher which may contain tadpoles of different ages.

Metamorphosis Metamorphosis is a biological process by which an animal physically develops including birth transformation or hatching, involving a conspicuous and relatively abrupt change in the animal's body structure through cell growth and different ...

takes place about a fortnight after the eggs are laid.

Status

This frog is seldom seen, perhaps because of its small size and inconspicuous appearance. Its numbers are thought to be in slow decline but the

International Union for Conservation of Nature The International Union for Conservation of Nature (IUCN) is an international organization working in the field of nature conservation and sustainable use of natural resources. Founded in 1948, IUCN has become the global authority on the stat ...

(IUCN) rates it as being of "

Least Concern A least-concern species is a species that has been evaluated and categorized by the International Union for Conservation of Nature (IUCN) as not being a focus of wildlife conservation because the specific species is still plentiful in the wil ...

" as it considers that the rate of decline is insufficient to justify listing it in a more threatened category. No particular threats to this species have been identified.

References

{{Taxonbar, from=Q1936018 borneensis Amphibians described in 1928 Taxa named by Hampton Wildman Parker Nepenthes infauna Endemic fauna of Borneo Endemic fauna of Malaysia Amphibians of Malaysia Taxonomy articles created by Polbot Amphibians of Borneo