Enhydrus, LAPORTE, 1835

GENUS ENHYDRUS LAPORTE, 1835 View in CoL

( FIGS 2 View Figure 2 , 4A View Figure 4 , 5D View Figure 5 , 6A View Figure 6 , 9F View Figure 9 , 12F–G View Figure 12 , 13A–C View Figure 13 )

Type species: Enhydrus sulcatus (Wiedemann, 1821) .

Synonyms: Epinectus Aubé, 1838, Epinectes Régimbart, 1877 , Prothydrus Guignot, 1954 .

Diagnosis: Within the tribe Dineutini , Enhydrus can be diagnosed by the following combination of characters: (1) antenna of most species with 7 flagellomeres ( Fig. 5D View Figure 5 ) – one with 6, (2) fons with lateral bead ( Fig. 4A View Figure 4 ), (3) pronotal transverse impressed line present, (4) elytral striae present as strongly impressed lines, (5) scutellar shield visible with elytra closed, (6) protibia laterally expanded apically (as in Fig. 8A View Figure 8 ), (7) broad, compact male protarsi ( Fig. 9F View Figure 9 ), protarsi of both sexes often with fused segments and large protarsal claws, (8) metaventrite medially pentagonal in shape ( Fig. 6A View Figure 6 ), (9) suture of abdominal sternite II present and (10) female RT without vagina shield, gonocoxae short and stout ( Fig. 12G View Figure 12 ).

Taxonomy: There are four known species in the genus. The species of Enhydrus were last treated taxonomically by Brinck (1978).

Distribution: Disparately distributed in South American and extreme south-eastern Central America ( Fig. 14C View Figure 14 ) ( Brinck, 1977).

Discussion: The genus Enhydrus lacks a single autapomorphy; however, retention of a fully developed suture to abdominal sternite II is unique to this genus. Fusion of the protarsomeres is unique to Enhydrus as well, but not all species exhibit protarsomere fusion (e.g. E. tibialis ). Molecular data ( Fig. S4 View Figure 4 ) however strongly support Enhydrus is a distinct monophyletic group, and in general morphology species strongly resemble one another, despite lacking a distinct synapomorphy.