Diagnostic key to species of the genus Scutiger in China (modified from Fei & Ye 2016, distribution followed Fei et al. 2012, Fei & Ye 2016 and modified following more recent literatures)

1a. Toes one-third or half webbed........................................................................... 2

1b. Toes webbing one-forth or less.......................................................................... 11

2a. Maxillary teeth distinct................................................................................. 3

2b. Maxillary teeth absent or only with weak budding of teeth..................................................... 6

3a. Distinct elongated tubercles on dorsum; fine nuptial spines on first three fingers and arms in males; no vocal sacs in males... ................................................................................................... 4

3b. Tubercles of dorsum not elongated; no nuptial spines on arms.................................................. 5

4a. Abdomen smooth in breeding males.................................................. S. chintingensis (Sichuan)

4b. Abdomen covered with horny spines in breeding males........................................ S. wolong (Sichuan)

5a. Body size large, adult SVL> 65mm; vocal sacs absent in males; fine nuptial spines present on first three fingers...................................................................................... S. macularis (Sichuan, Xizang)

5b. Body size small, adult SVL <60mm; vocal sacs present in males; distinctively enlarged nuptial spines on first two fingers only in males............................................................................ S. pardalotus (Yunnan)

6a. Adult large, male SVL greater than 70mm; forelimbs sturdy in males; dorsal tubercles without spinules................. 7

6b. Adult small, male SVL less than 70mm; forelimbs relatively slender in males; dorsal tubercles with distinct spinules..... 10

7a. Ventral tarsus and feet rough, covered with distinct tubercles; both axillary and pectoral glands covered with nuptial spines in breeding males............................................... S. glandulatus (Yunnan, Sichuan, Xizang, Qinghai)

7b. Ventral tarsus and feet smooth without distinct, small tubercles................................................. 8

8a. Nuptial spines covering pectoral but not axillary glands in breeding males.................................................................................................... S. mammatus (Yunnan, Sichuan, Qinghai?, Xizang)

8b. Nuptial spines covering both pectoral and axillary glands in breeding males....................................... 9

9a. No glands on posterolateral tarsus and tibia................................................ S. meiliensis (Yunnan)

9b. Glands present on posterolateral tarsus and tibia............................................ S. biluoensis (Yunnan)

10a. Nuptial spines present on abdomen in breeding conditions of both sexes; toe webbing two third or more.................................................................. S. boulengeri / bangdaensis complex (Qinghai, Sichuan, Xizang)

10b. Nuptial spines absent on abdomen in breeding conditions of both sexes; webbing near two third.... S. nyingchiensis (Xizang)

11a. Maxillary teeth distinct................................................................................ 12

11b. Maxillary teeth absent or only with feeble budding of teeth................................................... 14

12a. Body sturdy, SVL 68.8mm; nuptial spines present on pectoral glands only, absent on axillary glands; dermal fringes present on toes............................................................................... S. adungensis (Xizang)

12b. Body slender, SVL <57mm; nuptial spines present on both pectoral and axillary Glands; dermal fringes absent or very feeble. .................................................................................................. 13

13a. Vocal scas present in males; distinct tubercles absent on abdomen.................................. S. ching (Yunnan)

13b. Vocal scas absent in males; distinct tubercles present on abdomen, covered with nuptial spines during breeding season.................................................................................... S. ningshanensis (Shaanxi)

14a. Nuptial spines present on first three fingers in breeding males................................................. 15

14b. Nuptial spines present on first two fingers only in breeding males.............................................. 20

15a. Vocal sacs present in males............................................................................ 16

15b. Vocal sacs absent in males............................................................................. 17

16a. Body large, adult SVL> 70mm; nuptial spines present on both axillary and pectoral glands in breeding males; males with singular, internal vocal sac............................................................. S. wuguanfui (Xizang)

16b. Body small, adult SVL <60mm; nuptial spines present only on pectoral glands in breeding males; males with paired, internal vocal sacs...................................................................... S. gongshanensis (Yunnan)

17a. Nuptial spines present on pectoral glands only in breeding males............................................... 18

17b. Nuptial spines present on both pectoral and axillary glands in breeding males..................................... 19

18a. Distinct raised tubercles present on ventrolateral body, posterior thigh, and around cloaca; nuptial spines on pectoral glands large and sparse..................................................................... S. muliensis (Sichuan)

18b. No tubercles on ventrolateral body, posterior thigh, and around cloaca or feeble; nuptial spines on pectoral glands fine and concentrated............................................................................. S. lisu (Yunnan)

19a. Tubercles on dorsum flat; one-quarter webbing on toes.................................... S. jiulongensis (Sichuan)

19b. Tubercles on dorsum raised, distinct circular or elongated shape; only rudimentary webbing on toes..................................................................................................... S. tuberculatus (Sichuan)

20a. Dorsal tubercles conical or in distinctively raised short clusters, covered by a few large spines....................... 21

20b. Dorsal tubercles elongated and covered with fine black spines................................................. 23

21a. Dorsal tubercles conical, each bearing single spine; skin rough, with smaller tubercles densely scattered; black spines present on anteroventral branchium.............................................................. S. spinosus (Xizang)

21b. Dorsal tubercle either in short cluster and each bearing multiple spines, or distinctively enlarged circular shape but smooth.. .................................................................................................. 22

22a. Dorsal tubercles in short cluster, each bearing multiple spines; skin in between large tubercle clusters smooth, overall giving a warty-like appearance; toes without dermal fringes......................................... S. luozhaensis (Xizang)

22b. Dorsal tubercles circular shaped, some distinctively enlarged, all smooth without spines; smaller tubercles densely scattered in between, giving a rough appearance; toes with visible dermal fringes.......................... S. sikimmensis (Xizang)

23a. Tongue not notched posteriorly; no nuptial spines on abdomen in males..................... S. tengchongensis (Yunnan)

23b. Tongue slightly notched posteriorly; nuptial spines present on abdomen in males.................................. 24

24a. Black nuptial spines present on anteroventral forearms only in males and on both pectoral and axillary glands in females........................................................................................ S. feiliangi (Henan)

24b. Black nuptial spines present on anteroventral surface of brachium in males; no spines on pectoral glands in females...... 25

25a. Black nuptial spines present on anteroventral surface of both forearm and brachium in males; no spines on abdomen in females................................................................... S. pingwuensis (Gansu?, Sichuan)

25b. Black nuptial spines only present on anteroventral surface of brachium only in males; spines present on abdomen of females. .................................................................................................. 26

26a. Single pair of large glands lateral of cloaca; tubercles of dorsal tibia subequal to dorsal ones...................................................................................................... S. liupanensis (Ningxia, Gansu)

26b. No enlarged glands lateral of cloaca; tubercles of dorsal tibia smaller than dorsal ones... S. wanglangensis (Gansu?, Sichuan)