Otostigmus, Porat, 1876

Vu, Ha T., Nguyen, Hung D., Le, Son X., Eguchi, Katsuyuki, Nguyen, Anh D. & Tran, Binh T. T., 2020, A review and notes on the phylogenetic relationship of the centipede genus Otostigmus Porat, 1876 (Chilopoda: Scolopendromorpha: Scolopendridae) from Vietnam, Zootaxa 4808 (3), pp. 401-438 : 434-435

Key to Otostigmus species in Vietnam

1. Terga with longitudinal keels........................................................................... 2

- Terga without longitudinal keels......................................................................... 3

2. Terga with 3 or fewer longitudinal keels, antennae with 17 segments, teeth 4+4............................ O. amballae

- Terga with 5–7 longitudinal keels, antennae with 21 segments, teeth 4(6)+4(6).............................. O. scaber

3. Antennae with 17–18 antennomeres with more than three glabrous ones.......................................... 4

- Antennae with 20–21 antennomeres with first two ones and 1/3–1/2 of the third glabrous............................ 5

4. Antennae with 3 antennomeres glabrous................................................................... 7

- Antennae with 4 antennomeres glabrous......................................................... O. reservatus

5. Each coxosternal tooth with 6(8)+6(8) small teeth................................................. O. multidens

- Each coxosternal tooth with 3+3 or 4+4 small teeth.......................................................... 6

6. Penultimate prefemur with one spine, terminal leg with one tarsal spur, coxopleural process short, with 2–3 apical spines............................................................................................... O. spinosus

- Penultimate prefemur without spine, terminal leg without tarsal spur, coxopleural process long, with 5–7 apical spines................................................................................................. O. astenus

7. Coxopleural process with 5–7 apical spines, 2–3 lateral spines; terminal leg with many unarranged small spines (more than 26 spines) or some rows of bigger spines............................................................ O. aculeatus

- Coxopleural process with 1–3 apical spines................................................................ 8

8. Coxopleural process with 3 apical spines, without lateral spines. Sterna 2–20 with complete paramedian sutures...................................................................................................... O. politus

- Coxopleural process with one apical spine, without lateral spine. Sterna without paramedian sutures.......... O. voprosus