Classification Nudipleura (clade; this is [Pleurobranchiomorpha + the nudibranchs]) is skipped because (1) we are already short of ranks at this level of the tree and (2) it is useful to keep such a well-known name as Nudibranchia at its traditional Order level, as long as it is tenable.The concept of Nudipleura is nevertheless correct and has been given strong support by Grande et al. (2004 ...