Key to Acanthocyrtus species (adapted from Zhang et al. 2009)

1 Tenent hairs pointed; Ruanda-Urundi................................................ A. marginalis Salmon, 1956

- Tenent hairs clavate (as in Fig. 20E)....................................................................... 2

2 Dorsal head with 8 sutural mac; Th II with 26–33 posterior mac; mucronal proximal tooth clearly smaller than distal, mucronal basal spine surpassing the proximal tooth; Australia .................................... A. barrowensis Zhang, 2009

- Dorsal head with 7 or less sutural mac (Fig. 25A); Th II with up to 19 posterior mac; mucronal teeth subequal, mucronal spine

reaching the apex of proximal tooth (Fig. 24E).............................................................. 3 3 Th II with 4–11 posterior mac, labial basomedian field without chaeta M2 (Fig. 25B)................................ 4

- Th II with 14–19 posterior mac, labial basomedian field with chaeta M2 .......................................... 5

4 Dorsal head with 5 sutural mac; Th II with 4 posterior mac, m1 mac absent; Abd I with two mac (m3–4); Australia ......................................................................................... A. spinosus (Schött, 1917)

- Dorsal Head with 7 sutural mac (Fig. 25A); Th II with 8–11 posterior mac, m1 mac present (Fig. 26A); Abd I with four mac (m2–5) (Fig. 26B).............................................................. A. lineatus Womersley, 1934

5 Dorsal head regions Gr I and II with 1+1 and 5 mac respectively; labial basomedian field with one reduced chaeta (M2); Australia .......................................................... A. yolngui Zhang, 2009 (in: Zhang et al. 2009)

- Dorsal cephalic regions Gr I and II with 2+2 and 4 mac respectively; labial basomedian field with three reduced chaetae (M2, R and RS); Australia............................................. A. loftyensis Zhang, 2009 (in: Zhang et al. 2009)