''Taruga eques'' (common names: Günther's whipping frog, Spurred Tree-frog, Montane Hour-glass Tree-frog) is a species of

tree frog A tree frog (or treefrog) is any species of frog that spends a major portion of its lifespan in trees, known as an arboreal state. Several lineages of frogs among the Neobatrachia suborder have given rise to treefrogs, although they are not clos ...

in the family

Rhacophoridae The Rhacophoridae are a family of frogs in tropical sub-Saharan Africa, South India and Sri Lanka, Japan, northeastern India to eastern China and Taiwan, south through the Philippines and Greater Sundas, and Sulawesi. They are commonly known as ...

. It is

endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

to the central hills of

Sri Lanka Sri Lanka, officially the Democratic Socialist Republic of Sri Lanka, also known historically as Ceylon, is an island country in South Asia. It lies in the Indian Ocean, southwest of the Bay of Bengal, separated from the Indian subcontinent, ...

Taxonomy

''Taruga eques'' is a species of tree frog in the

family, commonly known as shrub or flying frogs. The species was first described in 1858 by

Albert Günther Albert Karl Ludwig Gotthilf Günther , also Albert Charles Lewis Gotthilf Günther (3October 18301February 1914), was a German-born British zoologist, ichthyologist, and herpetologist. Günther is ranked the second-most productive reptile tax ...

, who named the species Polypedates eques. In 1882,

George Albert Boulenger George Albert Boulenger (19 October 1858 – 23 November 1937) was a Belgian-British zoologist who described and gave scientific names to over 2,000 new animal species, chiefly fish, reptiles, and amphibians. Boulenger was also an active botani ...

described the species as ''Rhacophorus eques.''

Ernst Ahl Christoph Gustav Ernst Ahl (1 September 1898 – 14 February 1945) was a German zoologist, born in Berlin. He was the director of the department of ichthyology and herpetology in the Museum für Naturkunde. He was also the editor in chief of th ...

upheld this classification in 1931 when he described the species as ''Rhacophorus (Rhacophorus) eques.'' In 1957, Kirtisinghe reclassified the species as ''Rhacophorus cruciger eques,'' and in 1992, the species was renamed again to ''Polypedates eques'' by Kelum Manamendra-Arachchi and Sushil Kumar Dutta. In 2010, the '' Taruga'' genus was established by a team led by Madhava Meegaskumbura, resulting in the species being renamed to ''Taruga eques.'' This reclassification was upheld in 2024 with the name ''Polypedates (Taruga) eques.'' The species is known colloquially as the Spurred Tree-frog, Gunther's Whipping Frog, and the Montane Hour-glass Tree-frog.

Evolution

The genus ''Taruga'' is considered a sister genus to ''

Polypedates ''Polypedates'' is a genus of frogs in the family (biology), family Rhacophoridae, the shrub frogs and Paleotropic tree frogs. They belong to subfamily Rhacophorinae. Members of this genus are collectively known as whipping frogs. They occur in ...

''. Divergence between these genus likely occurred in the

Sundaland Sundaland (also called Sundaica or the Sundaic region) is a biogeographical region of Southeast Asia corresponding to a larger landmass that was exposed throughout the last 2.6 million years during periods when sea levels were lower. It inc ...

region (possibly India) before ''

'' dispersed in a northerly fashion. The following

cladogram A cladogram (from Greek language, Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an Phylogenetic tree, evolutionary tree because it does not s ...

shows the phylogenetic position of ''Taruga eques'' among select members of the

family, based upon

Bayesian inference Bayesian inference ( or ) is a method of statistical inference in which Bayes' theorem is used to calculate a probability of a hypothesis, given prior evidence, and update it as more information becomes available. Fundamentally, Bayesian infer ...

and

maximum likelihood In statistics, maximum likelihood estimation (MLE) is a method of estimating the parameters of an assumed probability distribution, given some observed data. This is achieved by maximizing a likelihood function so that, under the assumed stati ...

comparison of mitochondrial and nuclear DNA:

Description

''Taruga eques'' is a large frog. Adult males measure and females in snout–vent length. Their snout is long, sharp, and triangular; females' snouts are a red-orange while males tend to be brown. The underside of the snout is a grey to cream-yellow color. The back pattern can vary from an hourglass shape to brown spots. The hind legs have dark stripes. ''Taruga eques'' resembles (and has been confused with) ''

Taruga fastigo ''Taruga fastigo'' is a species of frogs in the family Rhacophoridae. It is endemic to Sri Lanka and only known from its type locality, Morningside Estate near Rakwana. Prior to its description in 2001, it was confused with ''Polypedates eques'' ...

'' but ''Taruga eques'' has relatively shorter legs and has a narrower but longer head. Additionally, unlike ''Taruga fastigo'' they lack a black line that connects the axilla to the groin in, or, in some cases, that line is reduced to a band of blackish dots. ''Taruga eques'' can be differentiated from other ''

'' species by the presence of a

calcar The calcar, also known as the calcaneum, is the name given to a spur of cartilage arising from inner side of ankle and running along part of outer interfemoral membrane in bats, as well as to a similar spur on the legs of some arthropods. The cal ...

on the heel.

Polymorphism

''Taruga eques'' demonstrates polymorphic color differences between specimen. Males can present as brown, dark brown, and grey while females are red, orange, yellow orange, and red.

Ecology and behavior

Juncus effusus ''Juncus effusus'' is a perennial herbaceous flowering plant species in the rush family Juncaceae, with the common names common rush or soft rush. In North America, the common name soft rush also refers to ''Juncus interior''. Distribution ''J ...

'' and other herbs are often used as shelter to prevent desiccation of the frogs during the daytime. In the mid afternoon, ''Taruga eques'' will often begin emerging and vocalize until approximately midnight when observed. ''Taruga eques'' prefers humid environments greater than 65% and temperatures under 16 °C. They likewise prefer still bodies of water less than 16.5 °C. The species is predated by the

Indian Pond Heron The Indian pond heron or paddybird (''Ardeola grayii'') is a small heron. It is of Old World origins, breeding in southern Iran and east to the Indian subcontinent, Burma, and Sri Lanka. They are widespread and common but can be easily missed whe ...

, Indian Black Bird,

Mongooses A mongoose is a small terrestrial carnivorous mammal belonging to the Family (biology), family Herpestidae. This family has two subfamilies, the Herpestinae and the Mungotinae. The Herpestinae comprises 23 living species that are native to sou ...

, dragonfly larvae and the

Eurasian Otter The Eurasian otter (''Lutra lutra''), also known as the European otter, Eurasian river otter, European river otter, common otter, and Old World otter, is a semiaquatic mammal native to Eurasia and the Maghreb. The most widely distributed member o ...

Cestodes Cestoda is a class of parasitic worms in the flatworm phylum (Platyhelminthes). Most of the species—and the best-known—are those in the subclass Eucestoda; they are ribbon-like worms as adults, commonly known as tapeworms. Their bodies con ...

and leeches parasitize the species. ''Taruga eques'' is

sympatric In biology, two closely related species or populations are considered sympatric when they exist in the same geographic area and thus frequently encounter each other. An initially interbreeding population that splits into two or more distinct spe ...

with '' Fejevarya greenii, Pseudophilautus microtampanioum,

Pseudophilautus alto ''Pseudophilautus alto'' (common name: Horton Plains shrub frog) is a species of frogs in the family Rhacophoridae. It is endemic to the Central Highlands of Sri Lanka and known from the Horton Plains and Pattipola. Natural habitat of ''Pseudoph ...

,'' and other species of the ''

Pseudophilautus ''Pseudophilautus'' is a genus of shrub frogs in the family Rhacophoridae endemic to the Western Ghats of southwestern India and to Sri Lanka where the majority of the species are found. Many of them are already extinct (marked with † in the s ...

'' genus.

Mating

''Taruga eques'' is a terrestrial foam-nesting frog. Mating begins when males perform

mating call A mating call is the auditory signal used by animals to attract mates. It can occur in males or females, but literature is abundantly favored toward researching mating calls in females. In addition, mating calls are often the subject of mate choi ...

s to attract females. The mating pair will climb shrubbery or trees overhanging bodies of water. In particular, the flowering plant ''

'' is highly favored as a nesting site. The female secretes a mucus into the tree or shrub that she will kick with her hind legs until it forms a thick, white foam, and the male simultaneously fertilizes the eggs. Following this, the female will deposit the eggs into the resulting foam nest. Nest size varies from 12 to 195 cm2, and is largely dependent on environmental factors. The average nest is built above the water; with a maximum height of having been observed. Nest construction is designed such that tadpoles emerge and drop into the water below, but does not occur closer than 15 centimeters due to the risk of nest inundation by season rains. The outermost layer of the foam nest dries quickly after being laid to provide additional protection.

Habitat and conservation

''Taruga eques'' inhabits montane tropical moist forests in the central hills of

at elevations of

above sea level Height above mean sea level is a measure of a location's vertical distance (height, elevation or altitude) in reference to a vertical datum based on a historic mean sea level. In geodesy, it is formalized as orthometric height. The zero level ...

. It is both

arboreal Arboreal locomotion is the locomotion of animals in trees. In habitats in which trees are present, animals have evolved to move in them. Some animals may scale trees only occasionally (scansorial), but others are exclusively arboreal. The hab ...

and

terrestrial Terrestrial refers to things related to land or the planet Earth, as opposed to extraterrestrial. Terrestrial may also refer to: * Terrestrial animal, an animal that lives on land opposed to living in water, or sometimes an animal that lives on o ...

, being found in canopies and on tree trunks as well as in grasses at the edge of ponds. It is present in the

Horton Plains National Park Horton Plains National Park () is a national park in the central highlands of Sri Lanka that was designated in 1988. It covers an area of 31km² and borders Thotupalakanda Nature Reserve. It is located at an elevation of and encompasses montane ...

Hakgala Strict Nature Reserve Hakgala Strict Nature Reserve is one of the three strict nature reserves in Sri Lanka, the only one in the wet zone. The reserve is an important although isolated cloud forest which supports a number of faunal species including some endemics. Th ...

, Knuckles Mountain Forest Reserve, and the Peak Wilderness Sanctuary. 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 are often found in both permanent and seasonal ponds. While it is commonly found in Sri Lanka, it is classified as endangered by the

IUCN 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 status ...

due to

habitat loss Habitat destruction (also termed habitat loss or habitat reduction) occurs when a natural habitat is no longer able to support its native species. The organisms once living there have either moved elsewhere, or are dead, leading to a decrease ...

. It does not occur in habitats that have been modified by human action, showing that the species many not be able to tolerate human impacts to its environment. Knuckles Mountain Forest Reserve, a known habitat for the species, has recently been threatened by tea and

cardamom Cardamom (), sometimes cardamon or cardamum, is a spice made from the seeds of several plants in the genus (biology), genera ''Elettaria'' and ''Amomum'' in the family Zingiberaceae. Both genera are native to the Indian subcontinent and Indon ...

plantations, unregulated construction, tourism, man-made forest fires, and

invasive species An invasive species is an introduced species that harms its new environment. Invasive species adversely affect habitats and bioregions, causing ecological, environmental, and/or economic damage. The term can also be used for native spec ...

. Decreases in rainfall due to climate change, subcutaneous parasitic infections, and

forest dieback Forest dieback (also "", a German loan word, ) is a condition in trees or woody plants in which peripheral parts are killed, either by pathogens, parasites or conditions like acid rain, drought, and more. These episodes can have disastrous con ...

have also been identified as possible threats to the species. The species' reliance on micro habitats made of ''Juncus efficus'' and ecological specialization are seen as existential risk factors for the species.

Gallery

Taruga eques (adult stage).jpg, adult stage with "dorsal spots" pigment pattern found in world heritage Horton Plains National Park Taruga eques at Haggala.jpg, at Haggala Taruga eques at Haggala3.jpg, at Haggala Taruga eques (adult stage) at Horton Plains National Park.jpg, adult stage with dark brown dorsal colouration found in world heritage Horton Plains National Park Taruga eques.jpg, adult stage with yellow dorsal colouration found in world heritage Horton Plains National Park

References

{{Taxonbar, from=Q28056349 eques Frogs of Sri Lanka Endemic fauna of Sri Lanka Taxa named by Albert Günther Amphibians described in 1858 Taxonomy articles created by Polbot