Echinothrix diadema (Linnaeus, 1758)

Arachchige, Gayashan M., Jayakody, Sevvandi, Mooi, Rich & Kroh, Andreas, 2019, An annotated species list of regular echinoids from Sri Lanka with notes on some rarely seen temnopleurids, Zootaxa 4571 (1), pp. 35-57 : 40

Echinothrix diadema (Linnaeus, 1758)

Material studied. WUSL/ER/212 (wet, with spines) from Hikkaduwa; WUSL/ER/213 (dry, denuded) from Hikkaduwa; WUSL/ER/214 (dry, denuded) from Hiriketiya; WUSL/ER/215 (dry, with spines) from Nilwella; WUSL/ER/216 (wet, with spines) from Nilwella.

Literature records for Sri Lanka. Herdman et al. (1904), Clark (1915), Fernando (2006), Jayakody (2012).

Distribution in Sri Lanka. Southern coast of Sri Lanka.

Recorded depth range in Sri Lanka. 1–2 m (present study), 62 m (previous records).

Habitat. Coral reefs and rocky reef platforms.

Observed occurrence in this study. Southern coast (Hiriketiya, Nilwella, and Hikkaduwa) of Sri Lanka.

Remarks. The test of E. diadema differs from that of E. calamaris in having no naked adapical medial zones in the interambulacra, no inflated aboral ambulacra, enlarged ambulacral tubercles at the ambitus, and large auricles with high connecting ridges in the interambulacra. In life, E. diadema tends to be black with bluish iridescence in strong sunlight, and the poison-gland bearing spines are not differentiated in color from the other primary spines.