Key to the world species of Alloscopus

Modified from Jantarit & Sangsiri (2020) and Zhang et al. (2020)

1 Mucro with a basal spine............................................................................... 2

- Mucro without a basal spine............................................................................ 3

2 Eyes 2+2; Abd. I with 2+2 mac.............................................. A. spinosus (Prabhoo, 1971) (India)

- Eyes 3+3; Abd. I with 3+3 mac........................................ A. strebeli Winter, 1966 (Peru and Ecuador)

3 Eyes absent......................................................................................... 4

- Eyes present........................................................................................ 11

4 Tibiotarsi I–II with smooth chaetae....................................................................... 5

- Tibiotarsi I–II without smooth chaetae.................................................................... 8

5 Th. II with 12+12 central mac........................................................................... 6

- Th. II with 10+10 central mac........................................................................... 7

6 Unguis without inner unpaired teeth......... A. deharvengi (Mari-Mutt, 1985) in Mari-Mutt (1985b) (Papua New Guinea)

- Unguis with inner unpaired teeth............................... A. liuae Zhang, 2020 in Zhang et al. (2020) (China)

7 Posterior face of ventral tube with 16 chaetae....................................................................... A. tetracanthus (Börner, 1906) (Australia, India, Thailand, Malaysia, Singapore, Indonesia, Papua New Guinea and Micronesia)

- Posterior face of ventral tube with 12 chaetae.......................... A. whitteni Jantarit & Sangsiri, 2020 (Thailand)

8 Ant. IV apical pin chaeta absent; Th. II with 11+11 mac................. A. namtip Jantarit & Sangsiri, 2020 (Thailand)

- Ant. IV apical pin chaeta present; Th. II with more than 11+11 mac............................................. 9

9 Th. II with 13+13 mac; Abd I without the ms................................... A. arborealis sp. nov. (Philippines)

- Th. II with 12+12 mac; Abd I with the ms................................................................ 10

10 Unguis with 1–2 inner unpaired teeth; manubrium with 4+4 smooth chaetae.................................................................................... A. thailandensis (Mari-Mutt, 1985) in Mari-Mutt (1985b) (Thailand)

- Unguis without inner unpaired teeth; manubrium with 3+3 smooth chaetae............................................................................................. A. bannaensis Zhang, 2020 in Zhang et al. (2020) (China)

11 Eyes 2+2; unguiculus without an outer tooth.................................. A. aspinosus (Prabhoo, 1971) (India)

- Eyes 1+1; unguiculus with an outer tooth................................................................. 12

12 Head mac Pa5 present................................................................................ 13

- Head mac Pa5 absent................................................................................. 14

13 Head mac A5 present and M3 absent; Abd. II with 1+1 lateral mac (m5); trochanteral organ with up to 25 spines; dens dorsally with a row with 5–14 spines................................................................................................. A. tenuicornis (Börner, 1906) (Indonesia, Papua New Guinea, Philippines, Micronesia and Hawaii)

- Head mac A5 absent and M3 present; Abd. II without lateral mac; trochanteral organ with 30–40 spines; dens dorsally with two rows with 27–55 spines....................... A. multispinatus (Mari-Mutt, 1982) (Indonesia and Papua New Guinea)

14 Head ‘M’ series with 1+1 mac (M1); Th. II–III with 13+13 and 7+7 mac, respectively; manubrium dorsally with 3+3 smooth chaetae....................................................... A. fallax Yoshii & Suhardjono, 1992 (Indonesia)

- Head ‘M’ series with 2+2 mac (M1–2); Th. II–III with 11+11 and 6+6 mac, respectively; manubrium dorsally with 4+4 or 5+5 smooth chaetae.................................... A. yosiius (Mari-Mutt, 1985) in Mari-Mutt (1985b) (Indonesia)