Chinese crocodile lizard

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Not to be confused with Shonisaurus or Shinosaur.

Chinese crocodile lizard
At the Newport Aquarium in Newport, Kentucky
CITES Appendix I (CITES)[2]
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Squamata
Clade: Shinisauria
Family: Shinisauridae
Ahl, 1930
Genus: Shinisaurus
Ahl, 1930
Species:
S. crocodilurus
Binomial name
Shinisaurus crocodilurus
Ahl, 1930

The Chinese crocodile lizard (Shinisaurus crocodilurus) is a

monotypic genus Shinisaurus.[6] It is the only living member of Shinisauria, a clade of lizards whose fossil record extends back to the Early Cretaceous
, over 120 million years ago.

Description

Anatomy

Chinese crocodile lizards are characterized by their green, colored with reddish necks. They often have alternating bands of light and dark patterns. Male Chinese crocodile lizards are more common than females, especially during the breeding season. On average, these lizards are 40-46 cm (16-18 in) long. Perhaps the lizards' most distinctive features are the rows of bony scales down its back and muscular tail, imitating those of a crocodile.[7] Additionally, Chinese crocodile lizards are sexually dimorphic and can be distinguished visually. Adult males are larger and more colorful than females, with their color intensifying during the breeding season.[8]

Gut microbes

The composition of gut

earthworms, especially during breeding seasons. Within the gut microbiota population, Bacillota and Pseudomonadota are the main microbiota found in the Shinisaurus crocodilurus. These two gut microbes are important across vertebrates and, for crocodile lizards, it benefits and aids in the species' metabolism, environmental information processing, genetic information processing and cellular processing.[9]

Behavior

Diet

In China, Shinisaurus crocodilurus is known to feed on both vertebrates and invertebrates. They are

"sit-and-wait" predators, perched on branches near streams until prey items are sighted. Invertebrates include both terrestrial groups (worms, spiders, katydids, etc.) and aquatic shrimp. Vertebrate prey includes tadpoles, small fish, and occasionally frogs and lizards. The Vietnamese subspecies prefers terrestrial invertebrates, such as cockroaches, crickets, and particularly earthworms. Vertebrates are not known to be part of their diet.[10][11][5]

Territorial behavior

Shinisaurus crocodilurus have been observed to be territorial and in a given pond or stream, one sole lizard will occupy the entire space.

Dipsosaurus dorsalis or Tropidurus spp., the Chinese crocodile lizards would also swing their tails and lunge at their competitors.[13] The dominant lizard will lunge and whip its tail, without force, at the subordinate lizard. The result of this is often little to no physical harm done to the subordinate. However, the subordinate lizard will retreat from the dominant's territory. [14] Another interesting dominance-establishing behavior for Shinisaurus crocodilurus is push-up behavior. The lizard would straighten its forelimbs and level the head. Unlike other lizards, the Shinisaurus crocodilurus would only perform this push-up motion with its anterior portion. While they were doing push-ups, Shinisaurus crocodilurus would sometimes bob their head in a circular motion.[14]

Reproduction

On average, Shinisaurus crocodilurus are fully mature and able to reproduce by the age of 3. They are

viviparous lizards, giving birth to 2-12 fully developed offspring every spring. The gestation period for lasts for up to 9 months.[8] This means that the mother does not have to take care of their offspring and that the offspring can survive independently.[15]
Female crocodile lizards are able to breed annually. Courtship often begins at the end of winter and breeding often occurs in the summer season, mainly July and August.

Pre-copulation for the Shinisaurus crocodilurus often begins with the adult male appearance changing to a more vibrant coloration.[8] Adult male lizards will display courtship behaviors like head-nodding and approaching the females. Successful copulation for the Shinisaurus crocodilurus is when the adult male approaches to bite the female adult on the neck. He then will move his body position to be on top of the female's and secure his tail below the female. This position is observed to be securing the position of the adult female to male contact with the cloaca. After ejaculation, the adult male will release the neck bite and physically release the female.[16]

Distribution and habitat

Surviving subpopulations of Chinese crocodile lizards primarily occupy isolated fragments of land in Guangxi and Guandong provinces of southeastern China. The Vietnamese subspecies is only found on Yên Tử Mountain in Quảng Ninh and Bac Giang provinces of northeastern Vietnam. Shinisaurus crocodilurus live alongside clear streams within subtropical broadleaf evergreen forests. They have a habitual preference for remote streams in undisturbed areas such as mountain ridges and dense forests.[10] The species lives in a relatively cool, monsoonal climate at moderately high elevations, 200-1500 meters (656-4921 feet) above sea level. Their preference to occupy less dense habitat is in-line with their antipredator trajectory towards flight rather than fight. Shinisaurus crocodilurus utilize tree holes, rocks, vegetated perches as shelter and are rarely found exposed on the forest floor.[12]

Taxonomy

Shinisaurus (literally "Shin's lizard") honors the biologist Sin Shu-szi [zh] (Chinese: 辛树帜; pinyin: Xīn Shùzhì), a member of a joint Chinese-German expedition that discovered this species (as well as the frog Quasipaa shini).[17] Its specific name – like the separate genus Crocodilurus – means "crocodile-tail".[18]

Subspecies

Two subspecies are recognized:[19]

  • Shinisaurus crocodilurus crocodilurus Ahl, 1930 (southeast China)
  • Shinisaurus crocodilurus vietnamensis Schingen et al., 2016 — Vietnamese crocodile lizard (northeast Vietnam)[10][20][21]

A subpopulation of Shinisaurus crocodilurus was first described from Vietnam in 2003.[22][23] They were named as a new subspecies (S. crocodilurus vietnamensis) in 2016, in light of several ecological, genetic, and morphological distinctions relative to the Chinese subpopulations. The Vietnamese subspecies preferred granitic mountains with warmer winters and overall milder temperatures. They tended to perch on higher branches above streams which were wider, more active, and not completely covered by vegetation. The diet was primarily terrestrial invertebrates, rather than aquatic vertebrates. In general, the head was slightly longer and more pointed, with smaller eyes and a shallower cheek region.[24][10]

Variation within the Chinese subspecies is poorly-understood. Genetic studies of captive individuals indicate that Shinisaurus crocodilurus is split into four clades, three of which originated in China and one of which corresponds to the Vietnamese subspecies.[25] However, wild individuals and local breeding programs in China appear show low genetic diversity between subpopulations.[26]

Classification

Shinisaurus was once also regarded as a member of

helodermatids than to Xenosaurus.[28] It is now placed as the only living member of the clade Shinisauria within the Anguimorpha. The fossil record of Shinisauria extends back to the Early Cretaceous, over 120 million years ago, with fossils being known from Asia, Europe and North America.[29]

Conservation

Population dynamics

A 2008 study, based on a 2004 survey, estimated that 950 crocodile lizards were left in China, split into eight isolated subpopulations. The largest subpopulation, with around 350 individuals, represents 36% of the entire population in China. A 1978 survey estimated the presence of 6000 individuals, while a 1990 survey estimated around 2500 individuals in the entirety of China. This points to severe population decline, on the order of 70-90% per subpopulation, in the 1978-2004 period. Five subpopulations appear to have been

extirpated, including the only sites known from Hunan province. The smallest surviving subpopulations are likely unsustainable due to a lack of genetic diversity.[6] A 2013 survey estimated that around 60 adults were left in Vietnam.[12] Despite the discovery of an additional subpopulation near the border with China, the estimated adult population in Vietnam decreased to 41 by 2015. The rate of decline in Vietnam is nearly equivalent to 26 years in China.[30]

Threats

In 2014, Shinisaurus crocodilurus was listed as

pet trade, meat, and traditional Chinese medicine as a claimed cure for insomnia.[1] In Vietnam, the local subspecies is impacted by similar threats, as well as road construction and coal mining. Local tourism has also led to habitat loss and stream pollution.[6][1] Habitat loss will be amplified by climate change: one model argues that forest habitats with a climate suitable for the Chinese subspecies will be eliminated by 2080.[30]

The species was introduced into the international pet trade in the 1980s, with exports increasing to several hundred per year by the late 1980s. Population decline linked to increasing exports led to the species being listed on

CITES Appendix I, according to its ongoing threat of extinction enhanced by poaching and trade.[5]

Conservation measures

In China, subpopulations within

Zoo Dresden.[5]

The Vietnamese subspecies is entirely located within protected areas, but mining and tourism are poorly regulated. Brochures, posters, and petitions developed with the help of the

Nitrogen-15, likely a result of being fed with protein-loaded feeding insects. This forensic technique may help to differentiate true captive bred individuals from wild caught lizards which are merely labelled as captive bred.[36]

References

  1. ^ a b c d Nguyen, TQ; Hamilton, P; Ziegler, T [in French] (2014). "Shinisaurus crocodilurus ". IUCN Red List of Threatened Species. 2014. Retrieved 12 June 2014.
  2. ^ a b "Chinese Crocodile Lizard". Retrieved 2013-05-17. CITES Web Gallery.
  3. ^ Chinese Crocodile Lizard (Shinisaurus crocodilurus). Archived 2016-06-24 at the Wayback Machine The Sacramento Zoological Society.
  4. ^ "Chinese crocodile lizard". CITES. 12 December 2021. Retrieved 30 September 2023.
  5. ^ a b c d e f g h i j "CoP17 Prop. 33: Transfer Shinisaurus crocodilurus Ahl, 1930 from Appendix II to Appendix I" (PDF). 5 February 2016. Archived (PDF) from the original on 2020-02-16.
  6. ^ a b c d e Huang, C. M., et al. (2008). Population and conservation strategies for the Chinese crocodile lizard (Shinisaurus crocodilurus) in China. Animal Biodiversity and Conservation 31(2) 63-70.
  7. ISBN 0-7894-7764-5
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  8. ^ a b c "Chinese crocodile lizard". Smithsonian's National Zoo. 2018-04-24. Retrieved 2021-11-16.
  9. PMID 32390955
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  10. ^
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  11. ^
    S2CID 132902998
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  12. ^ a b c d e van Schingen-Khan, Mona; Pham, Cuong; Thi, Hang; Bernardes, Marta; Hecht, Vera; Nguyen, Truong; Bonkowski, Michael; Ziegler, Thomas (2014-09-01). "Current status of the Crocodile Lizard Shinisaurus crocodilurus Ahl, 1930 in Vietnam with implications for conservation measures". Revue suisse de zoologie; annales de la Société zoologique suisse et du Muséum d'histoire naturelle de Genève. 121: 425–239.
  13. JSTOR 1466994
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  14. ^ a b Ray, J.; Walley, Harlan (2003-01-01). "A Behavioral Study on Shinisaurus crocodilurus". Bulletin of the Chicago Herpetological Society. 38.
  15. ^ Uyeda, Linda; Yoshimi, Diane (2011-11-05). "Husbandry and Breeding of the Crocodile Lizard (Shinisaurus crocodilurus) at Woodland Park Zoo, Seattle, Washington, USA". {{cite journal}}: Cite journal requires |journal= (help)
  16. ProQuest 2385816278
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  17. ISBN 978-1-4214-0135-5
    . Shu-szi Sin led an expedition to southern China. His name was [pronounced] as "Shin" by the other expedition participants, who were all German.
  18. ^ The Vivarium. American Federation of Herpetoculturists. 1989. In 1930, he christened the new species Shinisaurus crocodilurus (literally, "Shin's lizard with crocodile's tail").
  19. ^ Shinisaurus crocodilurus at the Reptarium.cz Reptile Database. Accessed 17 February 2018.
  20. ^ Virata, John (19 December 2017). "Vietnamese Crocodile Lizard Discovered In 2003 Finally Confirmed As Separate Subspecies". Reptiles Magazine. Retrieved 28 December 2017.
  21. ^ "Crocodile lizard is one of 115 new species found in Greater Mekong". The Guardian. 19 December 2017. Retrieved 28 December 2017.
  22. ^ Le, Khac Quyet; Ziegler, Thomas (2003). "First record of the Chinese crocodile lizard from outside of China: report on a population of Shinisaurus crocodilurus Ahl, 1930 from North-Eastern Vietnam". Hamadryad. 27 (2): 193–199.
  23. ^ Ziegler, Thomas; Le, Khac Quyet; Vu, Ngoc Thanh; Hendrix, Ralf; Böhme, Wolfgang (2008). "A comparative study of crocodile lizards (Shinisaurus crocodilurus Ahl, 1930) from Vietnam and China". The Raffles Bulletin of Zoology. 56 (1): 181–187.
  24. ^ van Schingen, Mona; Bernardes, Marta; Bonkowski, Michael; Ziegler, Thomas (2015). "First Ecological Assessment of the Endangered Crocodile Lizard, Shinisaurus crocodilurus, AHL, 1930 in Vietnam: Microhabitat Characterization and Habitat Selection" (PDF). Herpetol. Conserv. Biol. 10 (3): 948–959.
  25. ^ Hanh T. Ngo, Tham T. Nguyen , Minh D. Le, Mona van Schingen-Khan, Truong Q. Nguyen, Anna Rauhaus , Miguel Vences, Thomas Ziegler. Genetic screening of captive crocodile lizards (Shinisaurus crocodilurus) in Europe. Int. Zoo Yb.(2019) 53: 250–269
  26. ^
    PMID 24618917
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  27. S2CID 86355757
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  28. S2CID 85271610
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  29. S2CID 89730027
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  30. ^
    S2CID 234986369
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  31. ^ "Prop. 41:Inclusion of Shinisaurus crocodilurus in Appendix II". 1989. Archived from the original on 2021-11-26.
  32. ^ a b c van Schingen M., Schepp U., Pham C.T., Nguyen T.Q., Ziegler T. 2015. Last chance to see? Review on the threats to and use of the Crocodile Lizard. TRAFFIC Bulletin 27: 19–26
  33. ^ Sprackland, Robert George (1991). "The biology of the Chinese crocodile lizard in captivity" (PDF). NCHS Captive Propagation and Husbandry Conference: 45–53.
  34. ^ Zollweg, Michael (2014). Studbook Breeding Programme Shinisaurus crocodilurus (Chinese crocodile lizard) – Annual report 2014 (PDF). Vol. 41136106. European Studbook Foundation.
  35. doi:10.1111/izy.12084
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  36. doi:10.1016/j.gecco.2016.03.004
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