This species is found around the South African coast from False Bay to Sodwana Bay, intertidally to at least 30 m.[2] It has been erroneously reported from Australia and Japan due to confusion with Phyllodesmium serratum.

Around the South African coast, the coral nudibranch is typically between 30 and 40 mm[3] in total length.

It is a slender pale-bodied aeolid with long paired pinkish cerata.

[4] Phyllodesmium horridum feeds on sea fans (gorgonians) of the genus Melitodes (family Melithaeidae).

[2] It has also been reported to feed on gorgonians of the genus, Acabaria (also family Melithaeidae).