Heterocentrotus mamillatus (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 : 41-42

Heterocentrotus mamillatus (Linnaeus, 1758)

Material studied. WUSL/ER/232, 233 (wet, with spines) from Nilwella. Literature records for Sri Lanka. Fernando (2006), Jayakody (2012).

Distribution in Sri Lanka. Southern coast of Sri Lanka.

Recorded depth range in Sri Lanka. 2–5 m (present study).

Habitat. Among rock boulders and in rock crevices.

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

Remarks. H. mamillatus can be distinguished from the other Sri Lankan echinometrids in having the test transversely elongated through the axis between ambulacrum II and interambulacrum 4, and very strongly developed, solid, thick primary spines that are bright red-brown in life. Distally, these spines are almost triangular in cross-section. The secondary spines are extremely short, truncated, and with a flattened tip.

This species was threatened by the marine curio trade and listed as a protected species in Sri Lanka under the Sri Lankan Fauna and Flora Protection Act (Amendment), No. 22 of 2009. To date, it is the only protected echinoid species in Sri Lanka.