Male genitalia - key features
Features used to categorise and identify the male genitalia
Aedeagus: simple / pronged
Sacculus type: bow / triangle / rectangle
Saccular features: anterior process / anterior projection / lateral process / lateral concavity / posterior process / posterior projection / teeth - at the angles, margins or on the ventral surface / margins smooth, dentate or crenate.
Transtilla: simple / elaborate
Aedeagus: simple / pronged
Sacculus type: bow / triangle / rectangle
Saccular features: anterior process / anterior projection / lateral process / lateral concavity / posterior process / posterior projection / teeth - at the angles, margins or on the ventral surface / margins smooth, dentate or crenate.
Transtilla: simple / elaborate
See male genital anatomy for a general overview of the structures of the male genitalia. The images below illustrate the categories used.
Assignment of some species to a particular saccular type is not always straightforward. The essential features used are these: For a sacculus to be triangular it must have an acute anteromedial, anterolateral and posterolateral angles. For a sacculus to be rectangular it must have identifiable anterolateral and posterolateral angles and more-or-less discrete anterior, lateral and posterior margins. Essentially, everything else is bowed, but the critical feature of a bowed sacculus is that it lacks an identifiable anterolateral angle and so has a continuous anterolateral margin (and lacks discrete anterior and lateral margins). Determination of whether or not an anterolateral angle is present depends upon satisfactory flattening of the preparation.