Key to the Species of Metajalysus

1 Head black dorsally, except for yellowish median and lateral carinae; abdomen extensively black, usually on basal one half or more; femora smooth, at most, with only tiny, indistinct setigerous tubercles...................................... 2

- Head brown dorsally, sometimes dark brown or black along gular area; abdomen yellowish brown, often dark brown on basal third; femora with distinct setigerous tubercles, especially near apices............................................ 3

2 Length of setae on antennal scape and femora short, subequal to or slightly greater than diameter of segments; middle ventral margin of male genital aperture nearly flat (Figs. 24, 25); distribution: Argentina ....................... horvathi Štusák

- Length of setae on antennal scape and femora one and a half to two or more times diameter of segments; middle ventral margin of male genital aperture with sharp inverted V-shaped process (Figs. 28, 29); distribution: Ecuador ........... pilosus, n. sp.

3 Smaller species, length 3.30–3.62 mm; pronotum with ca. 12–15 or more erect setae on either side of disc (Figs. 1, 2); femora clavate apically, yellowish brown with a distinct subapical dark brown band; middle ventral margin of male genital aperture with an inverted V-shaped process (Figs. 17, 18); distribution: Argentina .............................. clavatus, n. sp.

- Larger species, length 4.00- 4.68 mm, pronotum with ca. 5 or 6 erect setae on either side of disc (Figs. 4, 5); femora, more gradually enlarged to apex, yellowish brown to brown, with apex pale on darkest specimens; middle ventral margin of male genital aperture nearly straight across (Figs. 21, 22); distribution: Argentina and Bolivia ......................... graziae, n. sp.