Jaeger, 1833
H. (Mertensiothuria) fuscocinerea is a mottled grey/brown sea cucumber with dark white-ringed papillae [see Semper (1868) pl. XXVII (colour)]. It is a medium to large (>200 mm), cylindrical species that is pliable with soft tegument. Spicules are sometimes poorly formed; they include low tables with often a spinose disc, and often irregular buttons (H. fuscocinerea spicules[/l]). H. fuscocinerea is found on [l][m]Glossary[/m][r]Reef[/r]reefs, below rocks on flats.
Remarks: Within the subgenus, the distinction between fuscocinerea and pervicax is not too clear; however the latter does have quite reduced spicules.