Table 2 Definition of characters used for the construction of the morphological character matrix

1

Single type of secondary sensory cells (present = 1, absent = 0)

2

Secondary sensory cells with a single cilium (monociliary) (present = 1, absent = 0)

3

Secondary sensory cells with two cilia (biciliary) (present = 1, absent = 0)

4

Secondary sensory cells with more than two cilia (multiciliary) (present = 1, absent = 0)

5

Cilia in multiciliary sensory cells of same length (0) / different lengths (1)

6

Microvilli or stereovilli on sensory cells (present = 1, absent = 0)

7

Microvilli on monociliary sensory cells (present = 1, absent = 0)

8

Stereovilli on monociliary sensory cells (present = 1, absent = 0)

9

Cilium of monociliary sensory cell surrounded by a ring of microvilli (0) or cilium eccentric to microvilli (1)

10

Microvilli on multiciliary sensory cells (present = 1, absent = 0)

11

Cilia in multiciliary sensory cells in a single line (0) or in multiple lines (1)

12

Accessory secretory cells in coronal organ (present = 1, absent = 0)

13

Supporting cells form a wall or crest alongside the coronal organ (present = 1, absent = 0)

14

Electron dense granules in sensory cells (present = 1, absent = 0)

15

Width of coronal organ uniform along oral rim (0) or wider at certain areas (1)

16

Accessory centriole in sensory cells (present = 1, absent = 0)

17

Tentacles or flaps present (present = 1, absent = 0)

18

Tentacles simple (0) / branched (1)

19

Secondary sensory cells in continuous row (present = 1, absent = 0)