Alloceramaster irritatus

The species has a pentagonal body. Abactinal plates are covered by a granular layer that forms a discrete cover over individual plates. Radial plates are wide, round to polygonal, and display peripheral rectangular granules. There are 6 superomarginal plates and 8 to 9 inferomarginal plates (with the distalmost small, upturned, and adjacent to the terminal plate). Superomarginals are covered by widely spaced granules (20–40) on a raised surface, otherwise covered by closely spaced round granules. Inferomarginal plates are numerous and dense, covered by polygonal to round granules. Furrow spines number 7 to 9 (distally 5 or 6). Subambulacral spines are arranged in 3 to 4 irregular series, decreasing in size from those adjacent to the furrow to those adjacent to the actinal plates.^[1]

This species is known from southeast of Norfolk Island (Norfolk Basin) at 530 meters and from off New Caledonia at depths of 428 to 470 meters.^[1]