Genus Hincksella Billard, 1918

Key to species

The following key comprises all species currently included in the genus Hincksella .

1. Colonies pinnate ……………………………………………………………………………………2

– Colonies with simple stems …………………………………………………………………………5

2. Hydrothecae shallow …………………………………………………… H. sibogae Billard, 1918

– Hydrothecae deep …………………………………………………………………………………3

3. Hydrotheca adnate for one-third ……………………………………… H. formosa (Fewkes, 1881)

– Hydrotheca adnate for half its length ……………………………………………………………4

4. Free part facing outward …………………………………………… H. alternans (Allman, 1888)

– Free part facing upward ………………………………………………… H. indiana Millard, 1967

5. Perisarc of hydrotheca finely and densely striated …………………………………………………6

– Perisarc of hydrotheca smooth or wrinkled ………………………………………………………7

6. Hydrotheca making an almost right angle with the stem ……………………… H. similis sp. nov.

– Hydrotheca making an acute angle with the stem …………………… H. neocaledonica sp. nov.

7. Perisarc of hydrotheca wrinkled ……………………………………… H. corrugata Millard, 1958

– Perisarc of hydrotheca smooth ……………………………………………………………………8

8. Hydrotheca exceedingly long …………………………………………… H. pusilla Ritchie, 1910

– Hydrotheca moderately long ………………………………………………………………………9

9. Aperture of hydrotheca facing outward ……………………………………… H. cornuta sp. nov.

– Aperture of hydrotheca facing upward …………………………………………………………10

10. Hydrotheca isodiametric throughout ………………………………… H. projecta (Fraser, 1938)

– Margin of hydrotheca distinctly flaring ……………………………… H. rigida (Fraser, 1938)