There is a fourth species which has an uncertain taxonomic status, Zesticelus japonicus which was described from Niigata in Japan in 1957 but the type has been lost.[2]
Characteristics
Zesticelus sculpins havee naked bodies which do not have scales or cirri. The branchiostegal membranes that are united and old over the isthmus, There are large pores in the sensory canals on the head, The highest spine on the preoperculum is long and slightly curved. There are teeth on the prevomer but not on the palatine.[5] These are small fishes with the largest species, Z. profundorum, having a maximum published total length of 6.4 cm (2.5 in).[4]
Distribution
Zesticelus sculpins are found in the North Pacific Ocean from Japan to California. They are deep sea species.[5]