Diadema savignyi (Audouin, 1809)

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 : 38-39

Diadema savignyi (Audouin, 1809)

Material studied. WUSL/ER/204 (dry, denuded) from Nilwella; WUSL/ER/209 (dry, denuded) from Hiriketiya. Literature records for Sri Lanka. Clark (1915), Fernando (2006), Jayakody (2012), Gayashan & Jayakody (2012).

Distribution in Sri Lanka. Southern coast of Sri Lanka.

Recorded depth range in Sri Lanka. 0.5– 4 m (present study).

Habitat. Shallow reef areas.

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

Remarks. The test of adult D. savignyi can be distinguished from that of adult D. setosum because the former has up to five primary tubercles in one horizontal series in the interambulacra, and the latter has six to seven. In life, D. savignyi lacks a red ring around the anus, but has bright blue lines around the plates in the apical system, and two paired, thin lines of the same vivid color running down along each interradial suture towards a white, iridescent spot. At this point, the two blue lines diverge to run along the center of each column of interambulacral plates. In D. savignyi , right blue lines can often be seen around the bases of the primary spines.

Clark (1915) reported this species in Sri Lanka for the first time based on two specimens housed at the Colombo Museum. However, no exact locality nor depth records are available. Clark’s collection is no longer available at the Colombo Museum.