Key to Subgenera of Nemadiolus (from Salgado, 2001)

1a Punctures of head fine or scarcely visible; punctures on pronotum weak and not reticulate............................ 2

1b Punctures on head wide, well-defined; punctures on pronotum wide, well defined and intermixed with slight reticulation................................................................................ subgenus Reticulonemadiolus

2a Antennal segments 9 and 10 more or less transverse; parameres and median lobe of aedeagus with setae on lateral margins; spiculum gastrale narrow; apex pointed; spermatheca simple, sacciform..........................subgenus Nemadiolus

2b Antennal segments 9 and 10 not transverse; parameres and median lobe of aedeagus lacking setae on lateral margins; spiculum gastrale wide, apex rounded; spermatheca with two well differentiated lobes................... subgenus Subnemadiolus