Originally proposed as a group of "worms" of uncertain affinity, to include both Neomenia
, which are respectively representative of the Solenogastres
(in the modern acception) anc Caudofoveata
. At that time the group was not considered as related to the Mollusca
There is a debate over whether Solenogastres
should be a subclass of a Class Aplacophora
or a separate class. The phylogenetic relationships of aplacophoran molluscs are not unambiguously resolved although the data at hand (see Haszprunar 2000: American Malacological Bulletin 15, 115-130, and Glaubrecht, Maitas & Salvini-Plawen, 2005: Mitteilungen aus der Museum für Naturkunde in Berlin – Zoologische Reihe 81, 145-166) would support a relationship like Solenogastres(Caudofoveata(Polyplacophora(Conchifera)))) making Aplacophora
paraphyletic. For this reason, contra
the Aculiferan hypothesis of Scheltema (1993: Biological Bulletin 184, 57-78) and in agreement with the European school of Salvini-Plawen, Solenogastres
and caudofoveata are given full class status.
Supraspecific classification used herein is essentially based on Salvini-Plawen (1978), also summarized in García–Álvarez & Salvini-Plawen (2007).