Key to Brazilian species of Hydrocanthus

1. Male prosternal process partially setose (Figs 2g, 3h) or entirely smooth (Figs 3c, 3e, 3g); male mesofemur anteroventral margin with a fine setose fringe, rising at base and extending to first ¼ of mesofemur (Figs 5a, 6a)....................... 2

- Male prosternal process entirely setose except along apical margin (Figs 2a, 2c, 2e, 2j, 3a); male mesofemur without modified setae (Figs 5b, 6b) or with ventrolateral margin with a tuft of long, rigid setae (Figs 5c, 6c)........................... 4

2. Males and females prosternum entirely smooth (Figs 3 c–d) or medially setose (Figs 3 e–f); Male metaventrite laterally setose, leaving a glabrous triangular area anteriorly (Figs 3c, 3e); female metaventrite entirely smooth (Fig. 3d) or setose along lateral margins (Fig. 3f). {TL = 3.80–5.30 mm; head and pronotum reddish-brown, elytra dark reddish-brown with yellowish marmorations (Fig. 1i); aedeagus as Figs 4s–u; distribution in Brazil: Amazonas, Bahia, Ceará, Espírito Santo, Goiás, Mato Grosso, Mato Grosso do Sul, Minas Gerais, Pará, Paraná, Rio de Janeiro, Rio Grande do Sul, Roraima, São Paulo and Sergipe}........................................................................ Hydrocanthus socius Sahlberg, 1844

- Male metaventrite setose in posterior ¼ or ½, leaving a glabrous rectangular area anteriorly (Figs 2g, 3 g–h); female metaventrite setose in posterior ½ or ¾, leaving a glabrous triangular (Figs 2 h–i) or semicircular (Fig. 3i) area anteriorly or setose along posterior margin, leaving a glabrous wide area anteriorly (Fig. 3j)............................................... 3

3. Male and female prosternal process setose along lateral margins with setation bands connecting at the basal center (Fig. 2 g–i); female prosternum laterally and medially setose (Fig. 2 h–i), sometimes divided by an irregular glabrous vertical band (Fig. 2i). {TL = 4.55–5.50 mm; head and pronotum reddish-brown, elytra very dark reddish-brown with yellowish marmorations (Fig. 1d); aedeagus as in Figs 4j–l; distribution in Brazil: Bahia, Espírito Santo, Mato Grosso, Mato Grosso do Sul, Minas Gerais, Pará, Paraná, Rio de Janeiro, Rio Grande do Sul, Santa Catarina and São Paulo}.......................................................................................................... Hydrocanthus levigatus (Brullé, 1837)

- Male prosternal process entirely smooth (Fig. 3g) or setose along lateral margins (Fig. 3h); female prosternum only laterally setose and prosternal process entirely smooth (Figs 3 i–j). {TL = 4.10–5.10 mm; head and pronotum light reddish-brown, elytra dark reddish-brown with yellowish marmorations (Fig. 1e); aedeagus as Figs 4v–x; distribution in Brazil: Bahia, Ceará, Minas Gerais, Rio de Janeiro, Roraima}.......................................... Hydrocanthus marmoratus Sharp, 1882

4. Female prosternal process entirely smooth (Fig. 3b); male mesofemur with ventrolateral margin with a tuft of long, rigid setae (Figs 5c, 6c). {TL = 4.40–5.20 mm; head and pronotum reddish-brown, black elytra with reddish marmorations (Fig. 1h); aedeagus as Figs 4p–r; distribution in Brazil: Paraná, Rio de Janeiro, Rio Grande do Sul and São Paulo}..................................................................................... Hydrocanthus sharpi Zimmermann, 1928

- Female prosternal process entirely setose except along apical margin (Figs 2b, 2d, 2f, 2k); male mesofemur without modified setae (Figs 5b, 6b)................................................................................... 5

5. Metaventrite setose in posterior?, leaving a glabrous subtriangular area anteriorly (Figs 2 a–b). {TL = 2.80–3.60 mm; head and pronotum light reddish-brown, elytra light reddish-brown with yellowish marmorations (Fig. 1a); aedeagus as Figs 4a–c; distribution in Brazil: Mato Grosso, Mato Grosso do Sul, Minas Gerais, Pará, Roraima and Tocantins}............................................................................................. Hydrocanthus ancus Guignot, 1942

- Metaventrite setose in posterior ¼ or ¾, leaving a glabrous triangular area anteriorly (Figs 2 c–f, 2k) or laterally and posteriorly setose, leaving a glabrous wide area anteriorly (Fig. 2j)....................................................... 6

6. Male metaventrite laterally and apically setose, leaving a glabrous wide area anteriorly (Fig. 2j). {TL = 4.30–4.95 mm; male head and pronotum light reddish-brown, black elytra with reddish marmorations (Fig. 1f); female head and pronotum reddishbrown, elytra dark reddish-brown with yellowish marmorations (Fig. 1g); aedeagus as Figs 4m–o; distribution in Brazil: Mato Grosso and Pará}.............................................. Hydrocanthus paraguayensis Zimmermann, 1928 - Male metaventrite setose in posterior ¼ or ¾, leaving a glabrous triangular area anteriorly (Figs 2c, 2e)................. 7

7. Aedeagus as Figs 4d–f. {TL = 3.00– 4.05 mm; head and pronotum light reddish-brown, elytra dark reddish-brown with yellowish marmorations (Fig. 1b); distribution in Brazil: Alagoas, Amapá, Amazonas, Bahia, Ceará, Espírito Santo, Goiás, Mato Grosso, Mato Grosso do Sul, Minas Gerais, Pará, Paraíba, Piauí, Rio de Janeiro, Rio Grande do Sul, Roraima and São Paulo}.......................................................................... Hydrocanthus debilis Sharp, 1882

- Aedeagus as Figs 4g–i. {TL = 3.15–3.90 mm; head and pronotum light reddish-brown, elytra dark reddish-brown with yellowish marmorations (Fig. 1c); distribution in Brazil: Mato Grosso, Pará and São Paulo}........................................................................................................ Hydrocanthus guignoti Young, 1985