Diadema, G RAY, 1825 AND

Coppard, Simon Edward & Campbell, Andrew C., 2006, Taxonomic significance of test morphology in the echinoid genera Diadema Gray, 1825 and Echinothrix Peters, 1853 (Echinodermata), Zoosystema 28 (1), pp. 93-112 : 96

KEY TO THE SPECIES OF THE GENERA DIADEMA G RAY, 1825 AND ECHINOTHRIX P ETERS, 1853 BASED ON TEST MORPHOLOGY

1. Apical system monocyclic ........................................................................................... 2

— Apical system hemicyclic ............................................................................................ 5

2. Swollen periproctal cone with white platelets present in the membrane. Large naked median areas present down the mid-lines of the interambulacra ...................................... 3

— Small periproctal cone with no white platelets present in the membrane. Many tubercles on genital plates .......................................................................................... E. diadema

3. Triangular-shaped naked median areas on the interambulacra. Arch-shaped depressions on genital plates. Black anal ring present ..................................................... D. palmeri

— No triangular-shaped naked median on the interambulacra, no arch-shaped depressions on genital plates. No black anal ring. Green bands of iridophores present down the midlines of the interambulacra ......................................................................................... 4

4. Ambulacra prominently raised aborally. Genital plates significantly longer than wide .... .............................................................................. E. calamaris (brown colour morph)

— Ambulacra only slightly raised aborally. Genital plates not significantly longer than wide ................................................................................ E. calamaris (white colour morph)

5. Orange anal ring. Blue/green “spot” markings on genital plates ................... D. setosum

— No distinct orange anal ring. No “spot” markings on genital plates ............................ 6

6. Distinct arch-shaped depressions on the genital plates of adults (spines not banded) .... 7

— No arch-shaped depressions on the genital plates of adults (spines not banded) .......... 8

7. Test distinctly rounded pentagonal when viewed aborally. Test (in living echinoids) black with a brown tinge and only a faint pattern of blue iridophores down the mid-lines of the interambulacra ...................................................................................... D. mexicanum

— Test distinctly circular not rounded pentagonal when viewed aborally. Test (in living echinoids) distinctly black, with a bold pattern of iridophores down the mid-lines of the interambulacra ............................................................................................ D. savignyi

8. Interambulacral plates number 12-14, corresponding to fewer spines ... D. paucispinum

— Interambulacral plates number 15-16 ......................................................................... 9

9. Six series of primary tubercles on the interambulacra .............................. D. antillarum

— Four or five series of primary tubercles on the interambulacra ................. D. ascensioins