Black marsh turtle

Formerly under the genus Emys, black marsh turtles are now classified under Siebenrockiella. They were first described by the British zoologist John Edward Gray from three specimens from the collections of Thomas Bell. Black marsh turtles used to be monotypic within the genus Siebenrockiella until Diesmos et al. (2005) showed based on genetic studies and morphology, that the recently rediscovered and critically endangered Philippine forest turtles, until that time known as Heosemys leytensis, were actually very closely related. Philippine forest turtles were subsequently reassigned to Siebenrockiella under the subgenus Panyaenemys. They are classified under the subfamily Geoemydinae under the family Geoemydidae. Black marsh turtles are cryptodires, having the ability to pull their heads straight back into the shells; instead of folding their necks sideways along the body like in pleurodiran turtles. The specific epithet "crassicollis" comes from Latin crassus ("thick") and collum ("neck"). The generic name was coined in honor of the Austrian zoologist Friedrich Siebenrock. Siebenrockiella crassicollis are known by a variety of vernacular names among hobbyists, such as black terrapin, black mud turtle, Malaysian black mud turtle, fat-headed turtle, thick-necked turtle, and Borneo black leaf turtle. They are also known as kura-kura pipi-putih in Indonesian. ==Description==

. of a black marsh turtle. Adult black marsh turtles are usually small to medium-sized, averaging at around in length and rarely exceeding . Some individuals, however, are known to grow to twice this size. The powerful jaws are pale yellow to pale brown in color and curves upwards, earning it the charming name of 'smiling terrapin'. Black marsh turtles are sexually dimorphic. Males have concave plastra in contrast to the flat plastron of females. The markings around the eyes and throat, present in all juveniles, disappear among males upon reaching adulthood while they are retained in females. The tails are also longer and thicker for males than for females. Black marsh turtles have a diploid karyotype of 52 chromosomes. Very rare in turtles where the gender of developing embryos are usually determined by environmental temperatures. ==Distribution and habitat==

Black marsh turtles can be found in southern Vietnam, Cambodia, southern Myanmar (Tenasserim), central and peninsular Thailand, eastern and western Malaysia, Singapore, and the Indonesian islands of Java, Kalimantan, and Sumatra. A specimen discovered in the Cerucuk River on Belitung Island in May 2023 is the first official record of the species on the island and represents a significant range extension beyond previously recorded populations in Sumatra to the west and Borneo to the east. ==Ecology and behavior==

Black marsh turtles are predominantly carnivorous and prefer to feed underwater. Juveniles are typically more carnivorous than adults. Their powerful jaws are also capable of inflicting wounds if handled roughly. Life cycle Black marsh turtles reach sexual maturity at five years. The eggs are incubated for 68 to 84 days before hatching. The hatchlings are relatively large, measuring around . ==Relations with humans==

Black marsh turtles are culturally important to Buddhism. In Thailand, large numbers of black marsh turtles, along with the yellow-headed temple turtles (Heosemys annandalii) are released into temple and castle ponds and cared for by Buddhist monks. They are treated as sacred by the public, being believed to contain the souls of people who died while trying to rescue other people from drowning. One of their commons names, Siamese temple turtle, originated from this practice. In a study in 2010, black marsh turtles were among the turtles found to contain high levels of mercury in their tissues. Their consumption as food is discouraged as they have the potential to cause mercury poisoning. Black marsh turtles are now being captive bred both for conservation and for the pet trade. Captive bred black marsh turtles are preferable as pets, being healthier and more acclimated to handling than individuals captured from the wild and illegally exported. ==Conservation==

Black marsh turtles are classified as endangered by the International Union for Conservation of Nature. Aside from signatories to CITES, Black marsh turtles are also specifically protected in Thailand under the Wild Animals Reservation Protection Act (WARPA). General laws against the trade and/or capture of freshwater turtles or wildlife that also extend to black marsh turtles are also in place in Myanmar, Singapore, and Vietnam. Despite these sanctions, the greatest threat to black marsh turtles, along with other Southeast Asian freshwater turtles, is the rising demand for turtles for the international meat trade, particularly for the Chinese food markets. Black marsh turtle populations in Cambodia and Vietnam are already considered endangered for this reason. The plastra of black marsh turtles are also among those sought after for traditional Chinese medicine, particularly for a traditional preparation known as Kuei-Lu-Erh-Hsien-Chiao (KLEHC). Thousands of individuals are often confiscated regularly in shipments. Official records in 1999 show that around 135,000 individuals were exported within the span of 10 months in Malaysia alone. In addition to this, black marsh turtles are increasingly being threatened in its native range by habitat loss. ==See also==