Key to males of the A. crinitus -group

1 Huge hooks on the sides of T9 (Fig. 215).................................................... A. hamatus, sp. n.

1' T9 different......................................................................................... 2

2 T8 entire, caudal margin convex, straight, or shallowly concave (e.g., Fig. 218).................................... 3

2' T8 caudally excised and of complex shape (Figs. 227, 228, 233)............................................... 4

3 Penis very long and slender, trigonium with apical hook-shaped centema (Fig. 220). Parameres simple, with pointed apices. Adult taken under water (N. QLD)....................................................... A. submersus, sp. n.

3' Penis not strikingly slender, stout trigonium with apical tuft of spicules, no centema. Parameres long, their apices enlarged, with rasp-like armature (Figs. 225, 226)................................................ A. crinitus (Klausnitzer)

4 T9 carries two very long blades projecting from the body tip. They may curl and then resemble a screw (Fig. 22)............................................................................................... A. flagellifer, sp. n.

4' T9 transformed into two strongly curved rods with a few apical setae........................... A. enigmaticus, sp. n.