Prototrochus Beljaev & Mironov, 1982

O’Loughlin, Mark & Macintosh, Hugh, 2015, New Prototrochus species of sea cucumber from Australia (Echinodermata: Holothuroidea: Synaptida: Myriotrochidae), Zootaxa 3995 (1), pp. 264-270 : 266

Key to the Australasian species of Prototrochus Beljaev & Mironov, 1982

1. Myriotrochid wheel diameters relatively small, not more than 150 µ m............................................ 2

– Myriotrochid wheel diameters relatively large, no smaller than 150 µ m........................................... 4

2. Wheel spokes more than ten (spokes 12–15)........................ P. roniae sp. nov. (Great Australian Bight, 1479 m)

– Wheel spokes fewer than ten............................................................................. 3

3. Teeth around inner rim of wheels at least 27 (teeth 27–34)...... P. robbinsae sp. nov. (off Albany, Western Australia, 772 m)

– Teeth around inner rim of wheels no more than 22 (teeth 18–22).......................................................................... P. staplesi O’Loughlin (in O’Loughlin & VandenSpiegel, 2007) (off eastern Victoria, 1119 m)

4. Teeth around inner rim of wheels 30 and more (teeth 30–34)........................................................................... P. burni O’Loughlin (in O’Loughlin & VandenSpiegel, 2007) (off Point Hicks, Victoria, 2900 m)

– Teeth around inner rim of wheels no more than 30............................................................ 5

5. Largest wheel diameters more than 290 µ m (wheel diameters 155–297 µ m)...................................................................................... P. australis ( Beljaev & Mironov, 1981) (northern Tasman Sea, 1500)

– Largest wheel diameters no more than 250 µ m (wheel diameters 207–243 µ m)........................................................ P. taniae O’Loughlin (in O’Loughlin & VandenSpiegel, 2007) (off southern New South Wales, 996 m)