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Varanus nuchalis (GÜNTHER, 1872)

IUCN Red List - Varanus nuchalis - Near Threatened, NT

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Higher TaxaVaranidae, Platynota, Varanoidea, Anguimorpha, Sauria, Squamata (lizards)
Common Names 
SynonymHydrosaurus nuchalis GÜNTHER 1872: 145
Varanus nuchalis — BOULENGER 1885: 315
Varanus salvator nuchalis — MERTENS 1942: 258
Varanus salvator nuchalis — GAULKE 2001: 14
Varanus (Soterosaurus) nuchalis — KOCH et al. 2007
Varanus (Soterosaurus) nuchalis — KOCH et al. 2010
Varanus (Soterosaurus) nuchalis — BUCKLITSCH et al. 2016: 50 
DistributionPhilippines (Cebu, Ticao, Negros, Panay and Masbate, Philippines);

Type locality: Philippines. Restricted to Negros by MERTENS (1959) and KOCH et al. (2010).  
TypesHolotype: BMNH 1946.9.1.17, adult. 
DiagnosisDiagnosis: V. nuchalis is readily characterised by (1) the strongly enlarged, prominent nuchal scales (character X) on the neck (except for those situated directly along the medio-dorsal line) in combination with (2) low mean scale counts on the dorsal side (character XY = 94–138, mean = 109.45). In addition, V. nuchalis can be identified by the following combination of proportion and scalation features: (3) the nostrils’ position (index 2 = 1.78–2.13, mean = 1.93) at approximately two third the distance from the eye to the tip of the snout; (4) low mean scale counts around the tail at one third of its length (character R = 43–55, mean = 47.50); (5) but high mean scale counts around midbody (character S = 136–169, mean = 151.45); (6) and on the ventral side (especially from the gular fold to the insertion of the hind limbs, character T = 84–94, mean = 87.79); (7) specimens often display white markings on the head; (8) occasionally a bright medio-dorsal stripe on nape and dorsum; and (9) usually a reduction of the dorsal transverse rows of bright spots with the exception of recurring pairs of two large oval spots or ocelli positioned immediately left and right along the backbone. (10) The tongue of V. nuchalis is not entirely dark but flesh-coloured, with pigmentation increasing only above from the bifurcation towards the tips. For details about scalation features and colour pattern of the remaining Philippine members of the V. salvator complex we refer to Tables 3 and 5 in KOCH et al. 2010. 
EtymologyEtymology not given in original description, but according to Günther (1872) the species "is distinguished from all ist congeners by the extraordinary development of the nuchal scales", wich are described as "the scales on the neck are very large, larger than any of the scutes of the head…" 
  • Beolens, Bo; Michael Watkins, and Michael Grayson 2011. The Eponym Dictionary of Reptiles. Johns Hopkins University Press, Baltimore, USA - get paper here
  • Boulenger, G.A. 1885. Catalogue of the lizards in the British Museum (Natural History). Vol. 2, Second edition. London, xiii+497 pp. - get paper here
  • Gaulke, M. 2011. The herpetofauna of Panay Island, Philippines. Edition Chimaira, 390 pp.
  • Gaulke, Maren 2001. Varanus salvator nuchalis, eine wenig bekannte Unterart des Bindenwarans. Draco 7:42-49 - get paper here
  • Günther, A. 1872. On two species of Hydrosaurus from the Philippine Islands. Proc. Zool. Soc. London 1872: 145-146 - get paper here
  • Koch, A. 2010. Underestimated Diversity of Philippine Water Monitor Lizards (Varanus salvator Complex) Unraveled: a Contribution to the International Year of Biodiversity, 2010. Biawak 4 (2): 69-74 - get paper here
  • Koch, A., Auliya, M; Schmitz, A.; Kuch, U. & Böhme, W. 2007. Morphological studies on the systematics of south east Asian water monitors (Varanus salvator Complex): nominotypic populations and taxonomic overview. Mertensiella 16:109-180
  • Koch, A.; Gaulke, M. & Böhme, W. 2010. Unravelling the underestimated diversity of Philippine water monitor lizards (Squamata: Varanus salvator complex), with the description of two new species and a new subspecies. Zootaxa 2446: 1–54 - get paper here
  • Koch, André; Mark Auliya & Thomas Ziegler 2010. Updated checklist of the living monitor lizards of the world (Squamata: Varanidae). Bonn Zool. Bull. 57 (2): 127–136 - get paper here
  • Meneses CG, Siler CD, Alviola PA, Gonzalez JCT, Balatibat JB, Natividad CA, Brown RM 2022. Amphibian and reptile diversity along a ridge-to-reef elevational gradient on a small isolated oceanic island of the central Philippines. Check List 18(5): 941-948 - get paper here
  • Mertens, R. 1942. Die Familie der Warane (Varanidae), 3. Teil: Taxonomie. Abh. Senckenb. naturf. Ges., 466: 235-391
  • SUPSUP, Christian E.; Nevong M. PUNA, Augusto A. ASIS, Bernard R. REDOBLADO, Maria Fatima G. PANAGUINIT, Faith M. GUINTO, Edmund B. RICO, Arvin C. DIESMOS, Rafe M. BROWN and Neil Aldrin D. MALLARI 2016. Amphibians and Reptiles of Cebu, Philippines: The Poorly Understood Herpetofauna of an Island with Very Little Remaining Natural Habitat. Asian Herpetological Research 2016, 7(3): 151–179 DOI: 10.16373/j.cnki.ahr.150049 - get paper here
  • Sy, Emerson Y. and Ernest Kurt Tan. 2013. Geographic Distribution: Varanus nuchalis (white-headed water monitor lizard). Herpetological Review 44 (4): 627 - get paper here
  • Taylor, E.H. 1922. The lizards of the Philippine Islands. Department of Agriculture and Natural Resources, Bureau of Science, Government of the Philippine Islands, Manila, Publication no. 17: 269 pp. - get paper here
  • WELTON, L. J., I. RECCHIO, P. L. WOOD JR., AND R. M. BROWN 2020. Phyloforensics in Action: Genetic Identity and Island Provenance of an Illegally Trafficked Philippine Monitor Lizard. Herpetological Review 51: 215 - 220.
  • Welton, Luke J.; Perry L. Wood, Jamie R. Oaks, Cameron D. Siler, Rafe M. Brown 2014. Fossil-calibrated phylogeny and historical biogeography of Southeast Asian water monitors (Varanus salvator Complex). Molecular Phylogenetics and Evolution - get paper here
  • Welton, Luke J.; SCOTT L. TRAVERS, CAMERON D. SILER, RAFE M. BROWN 2014. Integrative taxonomy and phylogeny-based species delimitation of Philippine water monitor lizards (Varanus salvator Complex) with descriptions of two new cryptic species. Zootaxa 3881 (3): 201–227 - get paper here
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