Grande et al. (2004) already suggested that Opisthobranchs would appear as a paraphyletic group unless Siphonaria
be included. Dinapoli & Klussmann-Kolb (2010) confirm this result with new data (their Figure 2) but do not draw a formal conclusion regarding classification. They only state that "neither the monophyly of the Basommatophora
) nor the monophyly of the Thalassophila (Amphiboloidea
) is supported". Pending further clarification, the superfamily Siphonarioidea
is here listed together with other Heterobranchs of unsettled phylogenetic position.