Thursday, July 7, 2016

[Herpetology • 2016] Shinisaurus crocodilurus vietnamensis • Is there more than one Crocodile Lizard? An Integrative Taxonomic Approach Reveals Vietnamese and Chinese Shinisaurus crocodilurus Represent Separate Conservation and Taxonomic Units.

Shinisaurus crocodilurus vietnamensis  
Schingen, Le, Ngo, Pham, Ha, Nguyen & Ziegler, 2016

 DOI: 10.1016/j.zoolgart.2016.06.001   

The Crocodile lizard Shinisaurus crocodilurus, the only living representative of the family Shinisauridae, is a habitat specialist adapted to remote freshwater habitats within evergreen broadleaf forests. Its current distribution is restricted to few small and isolated remnant occurrences in South China and North Vietnam. Multiple anthropogenic threats such as massive habitat destruction and unsustainable over-collection for the international pet trade brought the species to the brink of extinction. We herein employed an integrative taxonomic approach including comprehensive molecular comparisons based on fragments of mitochondrial genes (cytochrome b, partial ND6, and partial tRNA-Glu) in concert with in-depth morphological and ecological analyses in order to determine the status of the extant populations. Based on molecular, morphological, and ecological differences, we herein describe a new subspecies, Shinisaurus crocodilurus vietnamensis ssp. n., from Vietnam. Our findings emphasize the importance of improved in situ conservation measures in both countries, as both China and Vietnam harbor unique Crocodile lizard forms. We also recommend additional ex situ conservation measures, i.e., separate conservation breeding management of the subspecies in order to maintain genetic integrity and adjust husbandry conditions according to detected differences in ecological niche occupation.

Keywords: Conservation units; Ecology; Molecular biology; Morphology; New subspecies; Shinisauridae

Fig. 7. Male holotype (IEBR 3806) of Shinisaurus crocodilurus vietnamensis ssp. n. in life.
Photo: C.T. Pham. 

Taxonomic Account
Shinisaurus crocodilurus vietnamensis ssp. n.

Holotype: Adult male, IEBR 3806 (TYT2012.1SC), collected on 02 July 2012 at an elevation of 407 m in Son Dong District, Bac Giang Province, Vietnam by Cuong The Pham (Fig. 7).

Diagnosis: Shinisaurus crocodilurus vietnamensis ssp. n. differs from the nominate form Shinisaurus c. crocodilurus from China by the following combination of morphological characters: a relatively lower ratio of head height (HH) to head length (HL) and cheek height (CHa) to head length (lower head and cheek); a relatively higher ratio of eye-naris distance (EN) to head length and lower ratios of eye-eye distance to head length and internares distance to head length (snout longitudinally elongated and transversely narrower); and a relatively smaller ratio of orbital diameter (Or) to head length. For further morphological, molecular and ecological separation of the new subspecies from the nominate form see also the section “Comparisons”.

Etymology: The subspecies is named after the country of origin.

Distribution: Currently, Shinisaurus crocodilurus vietnamensis ssp. n. is only known from small and isolated sites in Quang Ninh and Bac Giang provinces, Northeast Vietnam (see Fig. 6).

Natural History: Shinisaurus crocodilurus vietnamensis ssp. n. is adapted to granitic freshwater streams within the evergreen broadleaf forest, with moderate annual temperatures without large fluctuations. For more detailed information see van Schingen, Pham, et al. (2015).

Fig. 3. Variation in color patterns of Vietnamese Shinisaurus crocodilurus:
A: Adult male from Dong Son-Ky Thuong NR, Quang Ninh Province; B-D: Adult males from Yen Tu NR, Quang Ninh Province; E-G: Adult males from Tay Yen Tu NR, Bac Giang Province; H, J-L: Adult females from Tay Yen Tu NR; I: Adult female from Dong Son-Ky Thuong NR.
Photos: M. van Schingen.    DOI: 10.1016/j.zoolgart.2016.06.001 

Mona van Schingen, Minh Duc Le, Hanh Thi Ngo, Cuong The Pham, Quynh Quy Ha, Truong Quang Nguyen and Thomas Ziegler. 2016. Is there more than one Crocodile Lizard? An Integrative Taxonomic Approach Reveals Vietnamese and Chinese Shinisaurus crocodilurus Represent Separate Conservation and Taxonomic Units. [Gibt es mehr als eine Krokodilschwanzechse? Ein integrativer taxonomischer Ansatz zeigt, dass vietnamesische und chinesische Shinisaurus crocodilurus separate Schutz-, sowie taxonomische Einheiten darstellen].   Der Zoologische Garten.   DOI: 10.1016/j.zoolgart.2016.06.001