| Origin of specimens examined | Seychelles, Japan, New Cale- | Mauritius, Indonesia, Australia, |
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| donia, Cook Islands, Samoa, Fiji | New Caledonia, Fiji, Philippines |
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| Test colour | black | black |
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| Test shape | hemispherical | hemispherical |
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| Test distinctions | ambulacra slightly raised aborally | ambulacra slightly raised aborally |
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| Iridophore pattern (interambulacra) | blue lines (bold) | lines of blue spots |
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| Iridophore pattern (apical system) | blue ring (bold) | no apical ring |
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| Iridophore pattern (genital plate) | blue arch (bold) | blue spot of iridophores |
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| Mean horizontal test diameter (SD) | 68 mm (4.2 mm) | 76 mm (3.7 mm) |
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| Mean vertical test diameter (SD) | 38 mm (2.1 mm) | 40 mm (2.9 mm) |
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| Maximum horizontal test diameter observed | 78 mm | 84 mm |
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| Maximum vertical test diameter observed | 44 mm | 48 mm |
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| Markings on test (median area of | white spot marking (typically | white spot marking (day and |
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| interambulacra) | night only) | night) |
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| Markings on naked test (median area of | geographic variation, white spot/ | white line and spot markings |
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| interambulacra) | no spot | |
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| Markings on naked test (genital plate) | distinct arched depression | green/blue spot marking |
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| | (typically) |
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| Number of tubercles on genital plate | 1-3 tubercles | 3-5 tubercles |
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| Height to width (at widest point) ratio of | 0.69:1 | 0.72:1 |
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| genital plate |
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| Diameter of gonopore (% of genital plate | 28% | 25% |
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| height) |
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| Form of apical system | hemicyclic | hemicyclic |
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| Form of periproct (distinguishing features) | small black, no ring or platelets | small black, orange ring, no |
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| | platelets |
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| Apical system (% of horizontal test diameter) | 22-28% | 22-28% |
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| Periproct (% of horizontal test diameter) | 13-18% | 12-20% |
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| Peristome (% of horizontal test diameter) | 42-50% | 40-50% |
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| Ambulacra % of interambulacra (at ambitus) | 28-30% | 25-30% |
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| Tubercle structure | perforate and crenulate | perforate and crenulate |
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| Number of median series of tubercles on | variable (1 or 2) | variable (1 or 2) |
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| interambulacra |
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| Rudimentary tube feet present on the | no | no |
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| peristome |
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| Buccal tube feet present | 5 pairs | 5 pairs |
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| Spines present on the buccal plates | no | no |
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| Number of specimens examined | 200 | 200 |
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