Echinometra

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

Echinometra ex grupo mathaei (Blainville, 1825)

Material studied. WUSL/ER/225 (dry, denuded) from Hiriketiya, WUSL/ER/226 (dry, denuded) from Hikkaduwa; WUSL/ER/227 (wet, with spines) from Beruwala.

Literature records for Sri Lanka. Clark (1915, 1925), Price & Rowe (1996), Fernando (2006), Jayakody (2012), Gayashan & Jayakody (2012).

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

Recorded depth range in Sri Lanka. 0.5– 1 m (present study), 0.5– 5 m (previous records).

Habitat. Rocky shores, in rock crevices, among rock boulders, channels, and self-made burrows.

Observed occurrence in this study. Southern coast (Hiriketiya and Hikkaduwa) and the western coast (Beruwala) of Sri Lanka.

Remarks. E. mathaei can be distinguished from the other Sri Lankan echinometrids, except from E. oblonga , in having the test elongated through the axis between ambulacrum I and interambulacrum 3, and only four pore pairs in the pore arcs of the ambulacra.

E. mathaei and E. oblonga cannot be easily distinguished from each other. Mortensen (1943b: 394) admits that “there are no reliable characters in the test distinguishing oblonga from the typical mathaei ”. Hence, molecular analyses are required to distinguish these species unequivocally, although sperm morphology and spicules have been shown to be very useful in distinguishing some members of the E. mathaei species complex (Arakaki et al. 1998; Bronstein & Loya 2013).

Two colour variants, green and brown, occur in Sri Lanka. There is a high likelihood that more than one species is present on the island, pending full molecular analyses of additional specimens from across the range of echinometrids currently listed under the names E. mathaei and E. oblonga .