The East Pacific / South Pacific Boundary: New taxa and occurrences from Rapa Nui (Easter Island), New Caledonia and adjacent regions Author Mah, Christopher L. text Zootaxa 2021 2021-06-02 4980 3 401 450 journal article 5948 10.11646/zootaxa.4980.3.1 f36e1c1f-1bfa-4fbc-b2dd-5edf6c7173af 1175-5326 4896889 F1FCA8AC-A984-4547-8A05-F1993BDAEE7C Hacelia Gray, 1840 Gray 1840: 284 [as Ophidiaster ( Hacelia ) Agassiz, 1836b ]. Ludwig 1897: 209 ; H.L. Clark 1921: 36 ; Clark & Downey 1992: 271 (as Hacelia ). Comments. Hacelia is a genus of Ophidiasteridae , which includes six species, two in the Atlantic, one from South Africa , and the remaining three in the tropical Pacific, all occurring at moderate depths, 40– 200 m . Hacelia has granule-covered, abactinal plates arranged in regular longitudinal series in ten rows rather than eight and six as in Ophidiaster and Tamaria , respectively. In a manner similar to the differences between Ophidiaster and Tamaria , the boundaries between genera, such as Ophidiaster and Hacelia can be problematic depending on the definitions of how “full longitudinal row” is defined.