''Siebenrockiella leytensis'' is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

of freshwater

turtle Turtles are reptiles of the order (biology), order Testudines, characterized by a special turtle shell, shell developed mainly from their ribs. Modern turtles are divided into two major groups, the Pleurodira (side necked turtles) and Crypt ...

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

Philippines The Philippines, officially the Republic of the Philippines, is an Archipelagic state, archipelagic country in Southeast Asia. Located in the western Pacific Ocean, it consists of List of islands of the Philippines, 7,641 islands, with a tot ...

. It is classified as

critically endangered An IUCN Red List critically endangered (CR or sometimes CE) species is one that has been categorized by the International Union for Conservation of Nature as facing an extremely high risk of extinction in the wild. As of December 2023, of t ...

. It is known as the Philippine forest turtle, the Philippine pond turtle, the Palawan turtle, or the Leyte pond turtle. Despite the latter common name, it does not occur in the island of

Leyte Leyte ( ) is an island in the Visayas group of islands in the Philippines. It is eighth-largest and sixth-most populous island in the Philippines, with a total population of 2,626,970 as of 2020 census. Since the accessibility of land has been ...

but is instead native to the

Palawan Palawan (, ), officially the Province of Palawan (; ), is an archipelagic province of the Philippines that is located in the region of Mimaropa. It is the largest province in the country in terms of total area of . The capital and largest c ...

island group. It is locally known as ''bakoko'' in

Cuyonon Cuyonon is a regional Bisayan language spoken on the coast of Palawan and the Cuyo Islands in the Philippines. Philippine forest turtles are readily recognizable by their

ginkgo ''Ginkgo'' is a genus of non-flowering seed plants, assigned to the gymnosperms. The scientific name is also used as the English common name. The order to which the genus belongs, Ginkgoales, first appeared in the Permian, , and ''Ginkgo'' is n ...

-shaped vertebral scutes and a pale white to yellow line traversing across its head behind the ears. The previous characteristic has earned it the nickname of 'bowtie turtle'. Philippine forest turtles are classified under the

subgenus In biology, a subgenus ( subgenera) is a taxonomic rank directly below genus. In the International Code of Zoological Nomenclature, a subgeneric name can be used independently or included in a species name, in parentheses, placed between the ge ...

''Panyaenemys''. Together with the smiling terrapin ('' Siebenrockiella crassicollis''), it is one of the two species in the genus ''

Siebenrockiella ''Siebenrockiella'' is a small genus of black marsh turtles. It used to be monotypic but now has two species with the addition of the Philippine forest turtle (moved from the genus '' Heosemys''). The genus was originally erected in 1869 by John ...

''.

Description

Siebenrockiella leytensis vertebral scutes

Philippine forest turtles have brown to reddish brown to black carapaces that reach a length of . Larger individuals can reach in length, though this is relatively rare. A dorsal ridge (the keel) is only present in the posterior vertebral

scute A scute () or scutum (Latin: ''scutum''; plural: ''scuta'' "Scutum (shield), shield") is a bony external plate or scale overlaid with horn, as on the shell of a turtle, the skin of crocodilians, and the feet of Bird anatomy#Scales, birds. The ter ...

s or absent altogether. The front margin of the carapace is slightly to strongly serrated, with the marginal scutes projecting beyond the cervical scutes. The vertebral scutes are broader than long. The

plastron The turtle shell is a shield for the ventral and dorsal parts of turtles (the Order (biology), order Testudines), completely enclosing all the turtle's vital organs and in some cases even the head. It is constructed of modified bony elements such ...

is reddish brown to black, sometimes with blotches of yellow. In juveniles, the plastron is a uniform yellow. The bridge (the hinge connecting plastron and carapace) is the same color as the plastron. It is significantly smaller than the carapace and narrow at the front and back. It possesses deep notches between the projecting gular scutes as well as between the gulars and humerals, but it is more distinct in the former. Its plastral formula is abd > pect > fem > gul > hum > an. The skin of the legs, body, and neck are rough in appearance, being covered in tiny tubercles. The head is brown in color, sometimes speckled at the temples with light brown, orange, or red spots. A thin white to pale yellow line traverses through the width of the head just behind the openings of the ears, it may be divided at the center in some individuals. This has led to the species being nicknamed as the 'bowtie turtle'. The line is more prominent in younger individuals. Heosemys leytensis02

The upper jaw is hooked and the skin on the sides of the neck and the chin are lighter in color. The lower jaw may also sometimes possess a pair of small yellow spots on the sides. The legs possess irregular enlarged transverse scales and are darker in color at the front. Four transverse scales are present on the forelimbs and more at the hind limbs (though absent at the heels). All limbs are webbed and possess large claws on all toes. The tail is uniformly light brown in color. Philippine forest turtles are relatively easy to recognize. They can be distinguished from all other turtles by their strongly projecting epiplastra, vertebral scutes shaped like ginkgo leaves, the absence of temporal arches in the

skull The skull, or cranium, is typically a bony enclosure around the brain of a vertebrate. In some fish, and amphibians, the skull is of cartilage. The skull is at the head end of the vertebrate. In the human, the skull comprises two prominent ...

, and the aforementioned light lines behind its head. The Malaysian giant turtle ('' Orlitia borneensis'') and the smiling terrapin (''Siebenrockiella crassicollis'') are the only other turtle species with ginkgo-shaped vertebral scutes, but they do not possess the white to pale yellow line on the back of their heads.

Taxonomy and nomenclature

The

scientific name 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 ...

of Philippine forest turtles is ''Siebenrockiella leytensis''. It is classified under the genus ''Siebenrockiella'' in the subgenus ''Panyaenemys'' (frequently misspelled as "''Panayanemys''" and "''Panyanemys''"). It belongs to the

subfamily In biological classification, a subfamily (Latin: ', plural ') is an auxiliary (intermediate) taxonomic rank, next below family but more inclusive than genus. Standard nomenclature rules end botanical subfamily names with "-oideae", and zo ...

Geoemydinae The Geoemydinae are a subfamily of turtles consisting of 60 subspecies and 76 taxa. These genera are placed here: * '' Batagur'' (six species, including part of Kachuga) * '' Chinemys'' (three species) (sometimes included in ''Mauremys'') * '' ...

of the family

Geoemydidae The Geoemydidae (formerly known as Bataguridae) are one of the largest and most diverse families in the order Testudines (turtles), with about 70 species A species () is often defined as the largest group of organisms in which any two in ...

.Turtles of the World: Annotated Checklist of Taxonomy and Synonymy, December 2010.
/ref> Formerly classified under the genus ''

Heosemys ''Heosemys'' is a genus of freshwater turtles ("terrapins" in British English) in the family Geoemydidae (formerly called Bataguridae). The genus ''Heosemys'' was split out of the related genus '' Geoemyda'' by McDowell in 1964. Species Four sp ...

'', it was transferred to the previously

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unisp ...

genus ''Siebenrockiella'' by Diesmos ''et al.'' in 2005 based on morphological and genetic comparison with ''Siebenrockiella crassicollis''. The subgenus name is derived after the Pala'wan word ''panya-en''. The word was used by a local Palawan resident to describe the turtles in a 2003 survey. The word means 'enchanted', supposedly because Philippine forest turtles were favorite pets of the

forest spirits A forest is an ecosystem characterized by a dense community of trees. Hundreds of definitions of forest are used throughout the world, incorporating factors such as tree density, tree height, land use, legal standing, and ecological functio ...

. ''-emys'' comes from the

Greek Greek may refer to: Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group *Greek language, a branch of the Indo-European language family **Proto-Greek language, the assumed last common ancestor of all kno ...

word εμύς, meaning 'freshwater turtle'. The generic name was coined in honor of the Austrian zoologist

Friedrich Siebenrock Friedrich Siebenrock (20 January 1853, Schörfling am Attersee – 28 January 1925, Vienna) was an Austrian herpetologist. Biography He studied zoology at the Universities of Innsbruck and Vienna, afterwards serving as a demonstrator under ...

. While the

specific name Specific name may refer to: * in Database management systems, a system-assigned name that is unique within a particular database In taxonomy, either of these two meanings, each with its own set of rules: * Specific name (botany), the two-part (bino ...

means 'from

he island of He or HE may refer to: Language * He (letter), the fifth letter of the Semitic abjads * He (pronoun), a pronoun in Modern English * He (kana), one of the Japanese kana (へ in hiragana and ヘ in katakana) * Ge (Cyrillic), a Cyrillic letter cal ...

Leyte'. An erroneous name, as the turtle is actually from the islands of Palawan and is not found in Leyte.

History of discovery

Philippine forest turtles were first described by the

American American(s) may refer to: * American, something of, from, or related to the United States of America, commonly known as the "United States" or "America" ** Americans, citizens and nationals of the United States of America ** American ancestry, p ...

herpetologist Herpetology (from Ancient Greek ἑρπετόν ''herpetón'', meaning "reptile" or "creeping animal") is a branch of zoology concerned with the study of amphibians (including frogs, salamanders, and caecilians (Gymnophiona)) and reptiles (in ...

Edward Harrison Taylor Edward Harrison Taylor (April 23, 1889 – June 16, 1978) was an American herpetologist from Missouri. Early life Taylor was born in Maysville, Missouri, to George and Loretta Taylor. He had an older brother, Eugene. Taylor studied at the Uni ...

in 1920 as ''Heosemys leytensis''. He described them on the basis of two specimens (male and female) collected by Gregorio Lopez, allegedly from the swamps of the municipality of Cabalian in

Southern Leyte Southern Leyte (; Kabalian: ''Habagatan nga Leyte''; ; ), officially the Province of Southern Leyte, is a province in the Philippines located in the Eastern Visayas region. Its capital and largest city is Maasin. Southern Leyte comprised the ...

(now known as the municipality of

San Juan San Juan, Spanish for Saint John (disambiguation), Saint John, most commonly refers to: * San Juan, Puerto Rico * San Juan, Argentina * San Juan, Metro Manila, a highly urbanized city in the Philippines San Juan may also refer to: Places Arge ...

). These specimens were unfortunately destroyed in

World War II World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...

during the

firebombing Firebombing is a bombing technique designed to damage a target, generally an urban area, through the use of fire, caused by incendiary devices, rather than from the blast effect of large bombs. In popular usage, any act in which an incendiary d ...

Manila Manila, officially the City of Manila, is the Capital of the Philippines, capital and second-most populous city of the Philippines after Quezon City, with a population of 1,846,513 people in 2020. Located on the eastern shore of Manila Bay on ...

. No other specimens were reported until 1988 when a specimen was bought from a local resident in

Taytay, Palawan Taytay, officially the Municipality of Taytay ( ), is a municipality in the province of Palawan, Philippines. According to the 2020 census, it has a population of 83,357 people. Since 2002, its Cathedral of St. Joseph the Worker is the epi ...

. Believing that the turtle got there through interisland trade, numerous herpetologists searched Southern Leyte for other individuals. Their lack of success led to fears that the turtle was already

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

. In 2001, during an assessment of endemic wildlife of the island of Palawan, live specimens of Philippine forest turtles were rediscovered. It soon became apparent that natural populations of the species existed in Palawan. Diesmos ''et al.'' (2004) have concluded that Taylor and/or Lopez may have somehow confused the type locality of the original specimens. Lopez also collected turtle specimens from the islands of Coron and

Busuanga Busuanga, officially the Municipality of Busuanga (), is a 3rd class municipality in the province of Palawan, Philippines. According to the 2020 census, it has a population of 25,617 people. History Oral tradition has it, that the entire islan ...

in Palawan. Specimens from Palawan may have been mistakenly exchanged with actual specimens from Leyte (which were probably ''

Cyclemys dentata The Asian leaf turtle (''Cyclemys dentata'') is a species of turtle found in Southeast Asia. They are quite common in the pet trade; their carapaces resemble that of a ''Cuora amboinensis'' hybrid. Feeding This species is omnivorous and feed ...

''). It is now presumed that Philippine forest turtles have never been introduced outside of Palawan, and thus were not actually from Leyte.

Distribution and habitat

Philippine forest turtles are known only from northern Palawan and surrounding islands. This includes the island of

Dumaran Dumaran, officially the Municipality of Dumaran (), is a municipality A municipality is usually a single administrative division having municipal corporation, corporate status and powers of self-government or jurisdiction as granted by natio ...

where the species is still relatively abundant in creeks. Elsewhere, it is believed their populations are declining sharply. Particularly in the areas of Taytay and San Vicente. Its distribution area is estimated to be less than 100 km².Sabine Schoppe and Chris R. Shepherd (2013): "The Palawan Forest Turtle Under Threat from International Trade", in ''Traffic Bulletin'', Vol.25, No.1, pg.9-11

Ecology and behavior

Philippine forest turtle populations often exist alongside other more common native turtle species, including Asian leaf turtles (''

'') and Southeast Asian box turtles (''

Cuora amboinensis The Amboina box turtle or Southeast Asian box turtle (''Cuora amboinensis'') is a species of Asian box turtle widely distributed across Southeast Asia. It is native to the Asian mainland from northeast India, through Bangladesh, Burma and Thail ...

''). Due to its rarity and its status as newly rediscovered, little is known of the life cycle of the Philippine forest turtle. From observations, however, Philippine forest turtles appear to exhibit long life spans and high adult survival rates. Like most turtles, their

sexual maturation Sexual maturity is the capability of an organism to reproduce. In humans, it is related to both puberty and adulthood. ''Puberty'' is the biological process of sexual maturation, while ''adulthood'', the condition of being socially recognized as ...

is delayed but they are able to mate multiple times before death (

iteroparity Semelparity and iteroparity are two contrasting reproductive strategies available to living organisms. A species is considered ''semelparous'' if it is characterized by a single reproductive episode before death, and ''iteroparous'' if it is c ...

). Captive adults confiscated from illegal traders were provided a large outside pool with well planted islands and numerous underwater rock formations in Malabon Zoo in Manila. But they proved to be very shy and retiring, spending considerable time hiding under rocks, both in and out of the water. They took some months to adjust to confinement. Observations indicate that they are omnivorous, favouring commercial turtle food, aquatic plants and they have been observed hunting small fish and crustaceans. They became active in the early morning and late evening, foraging for food, and moved about during the night. They were not observed to be keen on basking in the sun, but this may have been the result of being in a captive environment. Known food sources of Philippine forest turtles in the wild include

figs The fig is the edible fruit of ''Ficus carica'', a species of tree or shrub in the flowering plant family Moraceae, native to the Mediterranean region, together with western and southern Asia. It has been cultivated since ancient times and i ...

Threats

The Philippine forest turtle is an enigmatic freshwater turtle species, it exerts great fascination for turtle hobbyists. Due to the previous inability to locate it in the wild, probable threats from habitat loss, and potential pressure from collectors, this turtle is listed as

. Due to the susceptibility of the species to stress and the extremely aggressive territorial behavior of male individuals, Philippine forest turtles do not do well in captivity. Nevertheless, as of 2009, a considerable number of these turtles (over 171 individuals documented in a span of four years) were to be found for sale illegally in major Manila pet markets, particularly in the main Chinese markets (where the turtles are sold cheaper). The animals are not sold openly and some of the buyers are overseas collectors. Most of the individuals were juveniles or young adults. Between 2009 and 2011 this species ranked sixth among the most commonly confiscated species in the Philippines. These animals had been collected from mud wallows in northern Palawan, and it is believed that they hide during the daylight hours. Additionally, many specimens (from Palawan) offered for sale had small holes bored in the carapace, indicating that some at least had been held captive as pets and tethered accordingly. Local Palawan people are known to keep these animals in water troughs for domestic pigs, as these are supposed to bring luck for the household and the pigs, although it is not known if this luck is shared by the turtles. The unconfirmed existence of illegal trade of Palawan turtles to

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 ...

Malaysia Malaysia is a country in Southeast Asia. Featuring the Tanjung Piai, southernmost point of continental Eurasia, it is a federation, federal constitutional monarchy consisting of States and federal territories of Malaysia, 13 states and thre ...

, is also a cause of concern.

Conservation

Although some studies into their habitats have been commenced by several Philippines academic institutions, lack of funding has prevented full study, and they must be still considered endangered, especially from collecting, until further research had been carried out.

Trade Trade involves the transfer of goods and services from one person or entity to another, often in exchange for money. Economists refer to a system or network that allows trade as a market. Traders generally negotiate through a medium of cr ...

is banned internationally under the

CITES CITES (shorter acronym for the Convention on International Trade in Endangered Species of Wild Fauna and Flora, also known as the Washington Convention) is a multilateral treaty to protect endangered plants and animals from the threats of inte ...

convention, as well as domestically under the Philippines Wildlife Act. Some eighteen individuals have been donated to the Malabon Zoo north of

. Recent legislation in the Philippines requires pet owners and traders to register their animals with the authorities, and pay for licences to keep the more "exotic" pets. It is hoped that this may prove to reduce the collection of various endangered species, including the Philippines Pond Turtle. The entirety of the Palawan group of islands is also a nationally protected area.

References

External links

''Siebenrockiella leytensis'' Identification Sheet
fro
Environment CanadaOne of World’s Most Threatened Turtle Species Gets New Protected Home
{{Taxonbar, from=Q2716647 Reptiles of the Philippines Siebenrockiella Endemic fauna of the Philippines Fauna of Palawan Reptiles described in 1920