Prionocidaris pistillaris (Lamarck, 1816)

Fig. 16 A–C.

Prionocidaris pistillaris: A. Agassiz, 1863: 18; Mortensen, 1928a: 452 –456. Pl. XLIX. Pl. L. Pl. LI, Fig. 1. Pl. LXXIII, Fig. 18. Pl. LXXXVI, Figs 20–21; Clark & Courtman-Stock, 1976: 216 –217; Richmond, 1997: 295; Samyn, 2003: 200, Figs 2 D, D’, D”; Branch et al., 2010: 236, Fig. 106.1; Schultz, 2010: 61, Fig. 111.

Cidaris sp.: Bell, 1904: 168.

Prionocidaris baculosa: H.L. Clark, 1923 *: 370. Pl. XIII; H.L. Clark, 1924: 1.

Prionocidaris baculosa var. lineata var. nov . : H.L. Clark, 1925a: 14.

Material examined. MBC-A023316; A22665; MBC-A077765; MBC-A077770; MBC-A077780; MBC- A077761; MBC-A077755; MBC-A077754; MBC-A077764; A23724; MBC-A077753; MBC-A077751; MBC- A077756; MBC-A077752; MBC-A077760; MBC-A077763; MBC-A077762; MBC-A077769; MBC-A077759; MBC-A077766; MBC-A077758; MBC-A077757; MBC-A077757.

Identification. Test circular, tubercles not crenulated, pores distinctively conjugated. Apical disc tuberculated, tubercles along inner edge of genital plates appearing larger, oculars insert. Well-developed peristome. Primary spines uniformly set with thorns, becoming small towards end of the shaft; collar striped. Scrobicular spines having rounded point, miliary rather adpressed.

Global maximum size. Maximum test diameter 60 mm.

Global distribution. Kenya (Samyn 2003), Mauritius, Seychelles, Madagascar and East Africa from Tanzania to East coast of South Africa (Schultz 2010); from littoral to 200 m depth.

Remarks. Iziko Museum samples identified through this study document a 109 m depth extension from the previously known maximum depth of 91 m, to 200 m. Adults and juveniles differ in appearance, juveniles having fewer spines and being more vivid in color (Branch et al. 2010). Species similar to Plococidaris verticillata in oculars being insert, distinguished from one another in the spines, where P. verticillata has distinct whorls and P. pistillaris has a striped collar.