Key to the species of Leucascus

1. Skeleton composed only of triactines............................................................ L. protogenes

- Skeleton composed of triactines and tetractines.............................................................. 2

2. Diactines present...................................................................................... 3

- Diactines absent....................................................................................... 4

3. Diactines are club-shaped....................................................................... L. clavatus

- Diactines are microdiactines................................................................. L. albus sp. nov.

4. Tripods are present.................................................................................... 5

- Tripods are absent..................................................................................... 6

5. Only normal tripods......................................................................... L. leptoraphis

- Some tripods with a fourth rudimentary actine........................................................ L. lobatus

6. Colour alive pink and atrial skeleton composed mainly of tetractines....................................... L. roseus

- Atrial skeleton composed mainly of triactines............................................................... 7

7. Choanocyte tubes are mainly smooth............................................................... L. simplex

- Choanocyte tubes are mainly hispid....................................................................... 8

8. Colour alive white....................................................................... L. neocaledonicus

- Colour alive yellow....................................................................... L. flavus sp. nov.