Identification key for Western Atlantic species of Thrinacophora

(Details of spicule set see Table 3)

1a. Megascleres oxeas and styles............................................................................ 2

1b. Megascleres strongyles and styles (3 categories)...................................... Thrinacophora melae sp. nov.

2a. One category of styles.......................................................................... T. murrayi

2b. Two categories of styles................................................................................ 3

3a. Oxeas ≤ 250 μm............................................................................... T. spinosa

3b. Oxeas> 250 μm............................................................................. T. funiformis