TABLE 4 in Taxonomic significance of test morphology in the echinoid genera Diadema Gray, 1825 and Echinothrix Peters, 1853 (Echinodermata)

TABLE 4. — Test measurements, proportions and features Diadema palmeri Baker, 1967 and Echinothrix diadema (Linnaeus, 1758). Abbreviations: na, not applicable; SD, standard deviation.
D. palmeriE. diademaOrigin of specimens examinedPoor Knights Island, Hen andHawaii, Papua New Guinea,Chickens Island, New ZealandMaldives, Fiji (Dravuni, Yanuca,Taveuni islands)Test colourred (scarlet)black (blue/green tinge in youngadults)Test shapehemisphericalhemispherical, more roundedthan E. calamarisTest distinctionsambulacra slightly raised aborallyambulacra very slightly raisedaborallyIridophore pattern (interambulacra)blue/turquoise linesnoneIridophore pattern (apical system)blue/turquoise ringnoneIridophore pattern (genital plate)blue/turquoise arch (bold)noneMean horizontal test diameter (SD)65 mm (4.8 mm)92 mm (6.3 mm)Mean vertical test diameter (SD)35 mm (2.6 mm)55 mm (4.4 mm)Maximum horizontal test diameter observed78 mm110 mmMaximum vertical test diameter observed44 mm61 mmMarkings on test (median area ofnaked triangular area, cream inno markings, only small nakedinterambulacra)colourmedian areaMarkings on naked test (median area oflarge naked triangular area,no markings or pigmentationinterambulacra)Markings on naked test (genital plate)distinct arched depressionno markingsNumber of tubercles on genital plate2-6 tubercles4-8 tuberclesHeight to width (at widest point) ratio of0.54:10.85:1genital plateDiameter of gonopore (% of genital plate20%36%height)Form of apical systemmonocyclicmonocyclicForm of periproct (distinguishing features)small red cone, white platelets,small black anal cone, no ring orblack ringplateletsApical system (% of horizontal test diameter)29-32%20-25%Periproct (% of horizontal test diameter)16-18%12-15%Peristome (% of horizontal test diameter)35-45%38-46%Ambulacra % of interambulacra (at ambitus)20-25%22-26%Tubercle structureperforate and crenulateperforate and crenulateNumber of median series of tubercles on2nainterambulacraRudimentary tube feet present on thenonoperistomeBuccal tube feet present5 pairs5 pairsSpines present on the buccal platesnonoNumber of specimens examined20200