Suborder : PLAKOBRANCHACEA
Superfamily : PLAKOBRANCHOIDEA
Known only from Indonesia and the Philippines.
The body and parapodia are bright blue with a colour pattern of orange and black bands. The parapodia are edged with a broad orange band with a thin black line separating it from the inner blue area. The orange and black margin continue down on to the foot and down each side of the body completely enclosing the blue on the parapodia. The rhinophores are tipped with orange and black and the leading edge of the foot has a similar orange and black edge. There is a thin black line transversing the ‘neck’ region of the head just behind the base of the rhinophores. It is very similar in colour to Thuridilla undula the main difference being that the parapodial margin is very undulating, the inner border between the orange and black margin and the inner blue region forming a sinuous line.
See Thuridilla coerulea for comparison with the similarly coloured T. undula and T. lineolata.