Northumberland, England, and Aberystwyth, Wales. © P. Lightfoot.
In dorsal view, outline elliptical. Width about 50% of length when extended (right), but slightly wider when contracted (left).
18 tufts of long (0.6 to 1.0 mm) bristles which may be colourless or tinted orange, red or purple; arranged one tuft at each valve intersection and four bordering head valve i.