Pentaceraster Döderlein 1916

Yiu, Sam King Fung & Mah, Christopher L., 2024, New Ecological Observations and Occurrence for Asteroidea and Echinoidea in Hong Kong, Zootaxa 5526 (1), pp. 1-69 : 58

Pentaceraster Döderlein 1916

Pentaceraster is a highly diverse member of the Oreasteridae which currently includes 14 species and occurs widely across the Indo-Pacific.Although formally described by Döderlein, (1916, 1935, 1936), there is substantial variation within and among Pentaceraster species and other genera within the Oreasteridae , leading to some taxonomic controversy between species (e.g. Oreaster occidentalis and Pentaceraster cumingi ).

A guide and checklist of Pentaceraster spp. in Southern China and Hong Kong was presented by Liao & Clark (1995) with a key to species across the Indo-Pacific by Clark & Rowe (1971). We record two species, Pentaceraster alveolatus and Pentaceraster sibogae from Hong Kong waters, in addition to Pentaceraster magnificus as recorded from Hong Kong by Liao & Clark (1995) bringing the total number of Pentaceraster in Hong Kong to three.

Pentaceraster magnificus (Goto 1914) was compared with Pentaceraster regulus forma cebuana and Pentaceraster japonicus Döderlein 1916 . Descriptions of these species list the absent spination from the abactinal-lateral and marginal surfaces, suggesting they all likely conspecific with Pentaceraster magnificus . A more formal account of this synonymy is in preparation.

The other two species of Pentaceraster in Hong Kong are differentiated based on spination present on the marginal plates. Pentaceraster sibogae displays spines on all marginal plates with strongly developed spination on the abactinal and lateral surfaces, whereas Pentaceraster alveolatus displays spines only on the distal inferomarginal plates with indistinct or weakly developed abactinal-lateral spination.

Relatively little is known regarding the biology and ecology of Pentaceraster . Thomassin (1976) observed Pentaceraster mammilatus in the Indian Ocean, occurring primarily on eelgrass where he believed they were feeding on microalgae and biofilms. However observation herein suggests a broader range of prey.