The Echinoid Directory

Phylogeny and classification - 2

Character descriptions

Characters and data matrix supporting this cladogram

Apical disc
1. Ocular and genital plates form a contiguous ring in adults: no (0); yes (1)
2. Genital plates subdivided into a mass of small platelets: no (0); yes (1)
3. Ocular plates very elongate and extended: no (0); yes (1).
4. Gonopores open within genital plate (0); open in distal membranous gap (1)
5. periproctal plates: contiguous pavement (0); separated and embedded in membrane (1)

Ambulacra
6. Ambulacral zones: 2/3 or so width of interambulacra at subambitus (0); almost as wide or wider than interambulara at subambitus (1)
7. Smaller elements reduced to minute, ovate accessory plates: no (0); yes one is (1); yes both are (2).
8. On oral surface ambulacral plates occluded from adradial suture: no (0); inner plate occluded (1); both elements occluded (2).
9. On aboral surface primary element occluded from the adradial suture: no (0); yes (1)
10. On oral surface triads heterogeneous and tending to form multicomponent elements: no (0); yes (1).
11. Primary element divided medially into two pieces: no (0); yes (1).
12. On oral surface, pore-pairs marginal (0); forming a band removed from the adradial suture (1)
13. Pore-pairs adorally forming a broad marginal phyllode; no (0); yes (1).
14. Only one accessory plate on ambital and adoral elements: no (0); yes
15. All pores/tube-feet equally developed (0); some pore-pairs reduced (1)
16. Pore-pairs in three discrete columns at ambitus and aborally: no (0); yes (1).

Peristome
17. Buccal plates present: no (0); yes (1).
18. Plates arranged uniserially (0); biserially (1) in each half ambulacrum.
19. Buccal notches: absent (0); feeble (1); well developed (2).

Interambulacra
20. Membranous gaps present orally in interambulacral zones: no (0); yes (1).
21. Membranous gaps present adapically in interambulacral zones: no (0); yes (1).

Tuberculation
22. Primary tubercles: non-crenulate (0); crenulate (1).
23. Areole not sunken (0); sunken (1).
24. Oral tubercles much larger than aboral: no (0); yes (1).
25. Multiple equal tubercles on interambulacral plates: no (0); yes (1).
26. Distinct adradial column of tubercles: no (0); yes (1).

Spines and pedicellariae
27. Oral spines end: in rounded point with fleshy sac (0); in hyaline hoof (1); in flattened blade (2).
28. Sphaeridia: on both accessory plates (0); on inner plate only (1).
29. Tridentate pedicellariae: open blade-like valves with contiguous edges (0);
30. Tridentate pwedicellariae with involute neck and wide lateral gap (1)
30. Ophicephalous pedicellariae: absent (0); present (1).
31. Dactylous pedicellariae: absent (0); present (1).

Teeth
32. CLNP/LLNO system differentiated: no (0); yes (1).

Data matrix

Pelanechinus 10000 01101 00100 00110 00000 00011 00?
Kamptosoma 0?101 12000 00010 01000 01010 12000 010
Phormosoma 01001 02000 00000 00010 00111 00111 000
Hemiphormosoma 01001 02200 01000 00010 00111 00100 00?
Paraphormosoma 00000 02110 00000 00010 00000 00001 00?
Hygrosoma 00010 02000 00000 00010 00111 01001 101
Tromikosoma 01011 11100 01001 00000 00001 01010 10?
Sperosoma 01010 11100 11001 00010 00001 01010 101
Echinothuria 10000 02200 01000 10010 00010 11??1 ???
Asthenosoma 11000 02200 01100 10010 10011 01001 001
Hapalosoma 10000 02100 01100 10011 10010 11010 011
Araeosoma 10010 02200 01100 10111 10001 11001 011
Calveriosoma 10010 02200 01100 10111 10011 11001 001