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Anonymus. (2003). Previously un-described cryptic species complex of asian box turtle discovered. Natural Inquire, Bangkok, 2003(April, 1st).
Added by: Admin (14 Aug 2008 20:36:20 UTC) Last edited by: Beate Pfau (13 Sep 2008 16:59:19 UTC) |
| Resource type: Journal Article BibTeX citation key: Anonymus2003 View all bibliographic details  |
Categories: General Keywords: Cuora, Cuora amboinensis, Geoemydidae, Schildkröten = turtles + tortoises, Systematik = taxonomy, witz Creators: Anonymus Collection: Natural Inquire, Bangkok |
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| Abstract |
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Last winter biologists working in Laos became aware of an apparent sibling species of Asian Box Turtle. In general appearance this turtle looks like the common Asian Box Turtle, Cuora amboinensis, though there are minor, but consistent, differences in plastron markings. This discovery resulted in the researchers and their colleagues looking through museum collections, examining turtles in food markets, and visiting sites with Cuora amboinensis populations. In all sites and museum collections examined the undescribed species was discovered, but it always occurred in much lower numbers than the Asian Box Turtle. Cuora amboinensis has considerable morphological variation throughout its range, with a number of valid subspecies recognized. The biologists were surprised to discover that this variation was being mimicked by the less common and previously unrecognized species. DNA analysis showed the mimics to all be one species, and not closely related to Cuora amboinensis or any other described species of Cuora. Thus, they are not a sibling species as originally believed. Similarities are based on Batesian mimicry, and not on a close genetic relationship. Field observations indicated behavioral patterns similar to Cuora amboinensis in all aspects except diet. The new species, not yet formerly named, apparently lives largely off the blood of other turtles. With the mimic's appearance of Cuora amboinensis, the most abundant semi-aquatic turtle in SE Asia, the turtles do not even need to stalk their prey. The undescribed turtle takes advantage of mating and other social interactions to conduct surprise attacks on this and other Cuora. Single feedings are seldom fatal to the host turtle in that they can usually pull away from the bite and retreat into their shells within a few minutes. The ability of Cuora to close their shells with a hinged plastron has probably evolved as a defense against the parasitic turtles. The mimic also parasitized other species of turtles, and they have been observed to eat leeches that have recently fed. Some Asian leeches can be quite large. Not surprisingly, most rural people in SE Asia were aware of the blood feeding behavior. Technically these turtles are recognized as external parasites. The feeding of this undescribed Cuora is quite specialized. The tongue of these turtles is covered with bony rasp which efficiently cuts through the the skin of the host. The parasite hangs on with its mouth agape. Hooked like beaks on both the upper and lower jaw hold fast and the tongue is scraped repeatedly across the skin of the host. An anti coagulate is released from lining in the roof of the turtles mouth. Once blood starts to flow the licking motion stops and the tongue relaxes. In the relaxed position the sides of the tongue curl upwards forming a straw like tube through which the blood flows to the esophagus. Most flow is induced by gravity as the parasite hangs from the host turtle, but some suction pressure apparently is also applied. Hatchlings and yearlings closely resemble Snail-eating turtles, Malayemys subtrijuga , suggesting that they are more aquatic in early life and are perhaps diverged from a more primitive aquatic Cuora prototype. Cuora and other small semi-aquatic turtles are not the only host. These turtles have been seen feeding on freshwater turtles and even on large (50 pound) mountain tortoises. In Bohol Island in the Philippines the mimic Cuora are known to take blood from nesting marine turtles. The mimics wait till the seaturtles have completed nest construction and begin laying eggs. The parasitic turtles then attach themselves to the trailing edge of the seaturtles' fore limbs and drink. Occasionally as many as 15 adult Cuora can be seen feeding off one female seaturtle. Seaturtles returning to the ocean often have several Cuora still attached but they drop off prior to reaching the salt water. These blood sucking turtles are in turn host to a formerly unknown blood parasite. The parasite alternates generations between a relatively harmless adult stage and an active larval stage. The larval stage consumes red blood cells and greatly weakens the host. The adult stage forms cysts in the mouth of the cryptic parasitic turtles, releasing eggs during feeding bouts which find their way into the parasitized turtles. Once the larvae hatch they begin feeding on the red blood cells of turtles. It is believed that this process not only weakens the host but it makes them more vulnerable in their lethargic state to be parasitized again and again by the cryptic species. This strategy works in populations where both the parasitic turtle and its host have relatively limited home ranges. Chemical defenses in the cryptic species, which are absent in other turtles, prevent establishment of the larval blood parasite, or perhaps trigger it to go into its harmless adult form. The biologists are currently looking for other cryptic species that closely mimic other Cuora species and perhaps even turtles in other genera. Zoo curators and turtle hobbyist are now understanding the high, previously unexplained, mortality rate in their Asian turtle collections. All people who keep captive turtles should watch their animals closely to make sure that they do not have vampire turtles in their collections. Remember they are not dangerous to people, although health officials warn that they are likely to carry salmonella. These turtles need to be housed separately and in time they can be trained to drink reptile blood from a shallow dish. Captive pythons, monitor lizards, iguanas, corocodillians, and giant tortoises are all a good source of blood. Small amounts of blood can be safely and humanely extracted from these creatures on a daily basis. On green iguanas it may be easier to just cut off their heads. While these cryptic turtles are rare they are not considered to be a real conservation concern. In many portions of their range they are protected by national laws and regulations. All Cuora are protected by international CITES regulations and listed as CITES Appendix II. Thus, both the undescribed species and the various host turtles are fully protected.
Added by: Admin Last edited by: Beate Pfau |