Phyllacanthus imperialis (Lamarck, 1816)

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

Phyllacanthus imperialis (Lamarck, 1816)

Material studied. WUSL/ER/198, 199 (wet, with spines) from Godawaya; WUSL/ER/200 (dry, with spines) from Negombo; WUSL/ER/201, 202 (dry, denuded) from Nilwella.

Literature records for Sri Lanka. Agassiz (1872), Herdman et al. (1904), Clark (1915, 1925).

Distribution in Sri Lanka. Southern and western coasts of Sri Lanka.

Recorded depth range in Sri Lanka. 1–8 m (present study), 23–65 m (previous records).

Habitat. In coral ecosystems where it hides during the day in rock beds and emerges at night to graze.

Observed occurrence in this study. Southern coast (Godawaya, Nilwella) and western coast (Negombo) of Sri Lanka.

Remarks. This species differs from others in the genus by its characteristic primary spines with very numerous, closely spaced series of granules. Mortensen (1928) introduced three forms under Phyllacanthus imperialis : typicus, ustigerus, and unicolor. Specimens observed during this study most closely matched unicolor. Their primary spines are unbanded, and uniformly dark violet. This species was recorded from Sri Lanka 90 years ago by Clark (1925).