Identification key for Western Atlantic species of Placospongia

1. One category of tylostyles.............................................................................. 2

- Two categories of tylostyles............................................................................. 3

2. Tylostyles ≤ 500 µm; selenasters> 55 µm........................................................ P. intermedia

- Tylostyles> 550 µm; selenasters ≤ 50 µm........................................................... P. cristata

3. Spherules present (2–3 µm); selenaster size 23–76/10–65 µm...................................... P. melobesioides

- Spherules absent...................................................................................... 4

4. Spheraster microscleres present.................................................................. P. caribica

- Spheraster microscleres absent.......................................................................... 5

5. Spirasters (10–31 x 2–7 µm) present.............................................................. P. ruetzleri

- Spirasters absent; acanthomicrorhabds (6–13 x 2–4 µm), tylostyle I, 650– 1200 x 7.5–19.3; tylostyle II, 150–740 x 5–12.5.............................................................................. Placospongia giseleae sp. nov.