Identification key to the Hydrometra so far recorded from Brazil

1 Clypeus clearly longer than broad, elongate, or conate (Fig. 3).................................................. 2

- Clypeus broad, subquadrate (Figs 7–9)..................................................................... 5

2 Body length at most 12.5 mm; pro- and mesoacetabulum with 0–2 circular punctures each; metacetabulum without circular punctures........................................................................................... 3

- Body length at least 14.5 mm; pro- and mesoacetabulum with more than 10 circular punctures each; metacetabulum with circu- lar punctures............................................................ Hydrometra ollalai Mychajliw, 1961

3 Pro- and mesoacetabulum without circular punctures; male abdominal sternite VI without projections or brushes of setae (Fig. 5).......................................................................... Hydrometra sapiranga sp. nov.

- Pro- and mesoacetabulum with circular punctures; male abdominal sternite VI with projections or brushes of setae......... 4

4 Projections of male abdominal sternite VI spinose (Fig. 10); male genital segment I without lateral hooks (Fig. 10)................................................................................... Hydrometra argentina Berg, 1879

- Male abdominal sternite VI with two large elliptical, elevated areas very densely covered by stout, black spiniform setae (Fig. 11); male genital segment I with large lateral hooks (Fig. 11).................... Hydrometra sztolcmani Jaczewski, 1928

5 Anterior margin of clypeus excavated (Fig. 7)................................. Hydrometra comata Torre-Bueno, 1926

- Anterior margin of clypeus truncate, slightly rounded, or medially angulated, not excavated (Figs 8–9).................. 6

6 Pro- and mesoacetabulum without circular punctures................................ Hydrometra metator White, 1879

- Pro- and mesoacetabulum with circular punctures............................................................ 7

7 Male abdominal sternite VI with a pair of mammilose projections joined by a wide transverse ridge (Fig. 12)......................................................................... Hydrometra fruhstorferi Hungerford & Evans, 1934

- Male abdominal sternite VI with brushes of setae (Figs 13–14).................................................. 8

8 Clypeus with an angulose median projection (Fig. 8); projections of male abdominal sternite VI on posterior half of the seg- ment (Fig. 13)................................................. Hydrometra guianana Hungerford & Evans, 1934

- Clypeus with a blunt median projection (Fig. 9); projections of male abdominal sternite VI on the middle of the segment (Fig. 14)............................................................... Hydrometra caraiba Guérin-Méneville, 1857