Key to species of the genus Ferricixius Hoch & Ferreira, 2012

1 Compound eyes and tegmina well developed (Figs 1A, 3A–D). Flagellum of antenna without arista. Hind legs with 1 st and 2 nd tarsomere with 8 apical teeth (Figs 3E–F); ventral process of aedeagus curved distally with two teeth bigger than the others apically (Figs 4D–F); epigean species................................................. Ferricixius urieli sp. nov.)

– Habitus strongly troglomorphic (Figs 1B–D). Compound eyes and tegmina reduced or missing (Figs 6A–D, 9A–D). Flagellum of antenna with arista (Figs 9C 1, 13A–B). Hind legs with 1 st and 2 nd tarsomere with 4–6 apical teeth (Figs 6E–F, 9E–F, 13E). .................................................................................................. (2)

2(1) Second tarsomere of hind leg with 2 apical teeth (rarely 4). Flagellum of aedeagus with a “hook-shaped”, apically sharpened dorsolateral process. Aedeagal flagellum laterally without a “spine-like” process...................... Ferricixius davidi.

– Second tarsomere of hind leg with 4 apical teeth. Flagellum of aedeagus with a “spine-like” process left laterally (Figs 7E, 10E).............................................................................................. (3)

3(2) Aedeagal shaft with ventral process with 3 apical teeth, distally sinuous and very narrow (Figs 10D, F). Aedeagus left laterally with a strongly curved apical spine, reaching or, reaching or almost reaching the middle of the shaft (Fig. 10F).......................................................................................... Ferricixius goliathi sp. nov.

– Aedeagal shaft with ventral process serrated with about 14 apical teeth, process distally almost straight and very wide (Figs 7D, F). aedeagus ventro-laterally with a very short (less than half as long as aedeagus shaft) slightly curved subapical spine. (Fig. 7F)............................................................................. Ferricixius michaeli sp. nov.