Euprepiosaurus, Fitzinger, 1843

Weijola, Valter & Kraus, Fred, 2023, Two new species of monitor lizards (Squamata: Varanus) endemic to the Louisiade and Tanimbar Archipelagos with a key to the subgenus Euprepiosaurus, Journal of Natural History 57 (13 - 16), pp. 947-975 : 971-972

A dichotomous key to the subgenus Euprepiosaurus

Most monitors go through some form of ontogenetic colour change from hatchling to maturity, making it difficult to produce a key that accommodates all life stages. The colour-pattern characteristics used in the key provided below are adapted to animals that have passed the juvenile stage. It should also be taken into account that some characters – in particular yellow or white pigmentation of the tongue – are often lost in preserved specimens. For comparative purposes, photographs of most of these species in life may be found in Auliya and Koch (2020).

1. a. No blue pigmentation present on tail .................................................................................... 2

b. Blue pigmentation present on tail ........................................................................................ 16

2. a. Head black or brown with or without yellow markings ................................................. 3

b. Head completely yellow or yellow with some black markings ................ V. melinus

3. a. Dorsum charcoal grey to black with distinct yellow spots or spots and ocelli ..... 4

b. Dorsum uniform black or brown ........................................................................................... 15

4. a. Yellow temporal band typically present ................................................................................ 5

b. Yellow temporal band typically absent ................................................................................. 8

5. a. Dorsum black with yellow spots or incomplete ocelli typically not partially arranged in distinct crossbands ........................................................................................................................ 6

b. Dorsum black with distinct crossbands composed of yellow spots or spots and ocelli .......................................................................................................................................................... 7

6. a. Tail relatively long (1.6–1.9 as long as SVL), cheeks typically with some orange pigmentation .................................................................................................................... V. bennetti

b. Tail relatively short (1.35–1.55 as long as SVL), throat cream ... V. rainerguentheri

7. a. XY = 159–170, T = 107–109 .................................................................................. V. tanimbar

b. XY = 138–154, T = 93–100 ........................................................................................ V. indicus

8. a. Tongue white-yellow or pink with grey on tines or only on dorsodistal half ........ 9

b. Dorsal aspect of tongue completely blue-grey ............................................................... 14

9. a. Tongue pink with grey on tines or only half of dorsodistal aspect ........................ 10

b. Tongue white-yellow, sometimes with small grey markings, black temporal band present .................................................................................................................................... V. finschi

10. a. Pink or orange pigmentation typically present on cheeks, gular region or lateral aspect of neck .................................................................................................................................... 11

b. Pink or orange pigmentation typically absent on cheeks, gular region or lateral aspect of neck .................................................................................................................................... 12

11. a. Orange colouration typically present on cheeks and lateral aspects of neck Q = 87– 100, T = 101–113 .................................................................................................... V. louisiadensis

b. Pink colouration typically present on gular region, Q: 79–88, T. 92–102 ....................... ............................................................................................................................................. V. lirungensis

12. a. Throat distinctly bright white, dorsum with yellow ocelli .................................. V. colei

b. Throat cream coloured to yellow with or without black markings ......................... 13

13. a. Basal 1/3 of tail rounded without double scale ridge; dorsum black with small yellow spots, throat cream .................................................................................... V. juxtindicus

b. Basal 1/6 of tail rounded without double scale ridge; dorsum black with crossbands of yellow dots and ocelli, throat cream to yellow, often with black spots V. douarrha

14. a. Throat typically uniformly cream white to pale yellow, S = 100–145. ............................. ........................................................................................................................................ V. chlorostigma

b. Throat typically yellow with grey or black markings, Marianas, S = 101–126 .............. ............................................................................................................................................ V. tsukamotoi

15. a. Dorsum and head uniformly black, sometimes with small faint yellow spots, cheeks typically orange, throat black with or without white markings .......................... V. obor

b. Dorsum, tail and head uniformly olive-brown ............................................ V. zugorum

16 a) Throat peach; tongue uniformly pink; dorsum with narrow brown-black crossbands ................................................................................................................................................. V. jobiensis

b) Throat white or black and white; tongue other than uniformly pink; posterior dorsum without narrow black crossbands ........................................................................ 17

17 a) Throat light grey or white with few dark spots .............................................................. 18

b) Throat marbled black and white ........................................................................................... 19

18 a) Dorsum black or with black bands anteriorly, heavily spotted with yellow posteriorly, imparting a two-toned appearance to dorsum; tongue purple with yellow tines .................................................................................................................................................. V. yuwonoi

b) Dorsum black with turquoise and yellow spots or spots and ocelli; tongue pink with grey tines ............................................................................................ V. caerulivirens

19 a) Tongue yellow; dorsal scales (XY) = 153–180, Cape York and New Guinea region except Mussau and Crown ...................................................................................... V. doreanus

b) Tongue pink mottled with white and yellow; dorsal scales (XY) = 147–153, Mussau .................................................................................................................................................. V. semotus