Genus Acanthocyrtus Handschin, 1925

Type species: Acanthocyrtus spinosus (Schött, 1917)

These characters are shared by all Acanthocyrtus species so are not repeated in the species descriptions following: Tergal mac heavily ciliate apically, strongly or lightly foot-shaped or acuminate; smooth mic apically ramificate or not (Fig. 1). Eyes 8+8 (Figs 3F and 9D). Four prelabral chaetae smooth (Fig. 3D); labral formula with 4 (a1–2), 5 (m0–2), 5 (p0–2) smooth chaetae. Labial palp with five main papillae (A–E) plus one hypostomal papilla (H) with 0, 5, 0, 4, 3 (e6 absent), 2 guard appendages, respectively. Sublobal plate with 4 smooth appendages, 3 inner subquals and 1 minute distally (Fig. 4B). Labium with 5 proximal chaetae smooth and subequals in length (Fig. 4C). Basolateral and basomedian labial field with chaetae a1–5 smooth (Fig. 4C). Th II–Abd V with ms and sens formula 1, 0| 1, 0, 1, 0, 0 and 2, 2 | 1, 2, 2, +, 3, respectively (Figs 5 and 10); Abd II–IV bothriotrichal formula 2 (a5, m2), 3 (a5, m2, m5), 2 (T 2, T 4) (Figs 5 and 10); bothriotricha with accessory lance-shaped chaetae (Fig. 1). Mucro bidentate, apical tooth subequal to proximal tooth, basal spine surpassing the apex of the proximal tooth (Fig. 7E).