Netrostoma

Key to the species of Netrostoma:

1a. Warts or papillae projecting from top or sides of central dome...................................................................2

1b. Warts or papillae lacking; central dome knob-like; with 7 rounded velar lappets and 2 pointed rhopaliar lappets per octant; lacking appendages between the mouths; colorless to whitish in life [Northern QLD, Australia] ........................................................................................................................... Netrostoma nuda

2a. Top of dome covered with warts or papillae................................................................................................3

2b. Top of central dome smooth, with papillae projecting from sides in two whorls, the upper whorl with 8 large conical papillae, and the lower whorl with about 12 smaller papillae; 9 short lappets per octant; lacking mouth-arm filaments [Fiji] .............................................................................................. N. dumokuroa

3a. Central dome completely covered by about 50 or more warts or papillae ..................................................4

3b. Central dome with 10 wart-like projections; 6–8 rounded lappets per octant; with two types of appendages between the mouths: one thin and tubular, the other spindle-shaped [Malay Archipelago] N. coerulescens

4a. About 50 or more solid, pointed projections covering central dome; 6–8 flatly rounded velar lappets per octant; with numerous small, short appendages among the frilled mouths [Japan] ............ N. setouchiana

4b. About 80 rounded warts covering central dome; 8 rounded or cleft velar lappets per octant, ocular lappets sharp-pointed; filaments only on arm disk, small and spindle-shaped [Malay Archipelago] ...................... ......................................................................................................................................... N. typhlodendrium