Macrostomorpha

Macrostomorpha is a clade of free living flatworms ranked either as class or subclass in the group Rhabditophora. There are about 260 described species in two orders - marine, freshwater and brackish Macrostomida, which group most of the species diversity, and exclusively marine Haplopharyngida with only three described species. Macrostomorpha constitute a basal group in Rhabditophora, showing such plesiomorphic condition as entolecithal eggs and spiral cleavage. Another trait found among members of the clade is presence of hard stylet in the male copulatory organ.

The classification used here is a compromise between the more traditional taxonomy of Neodermata vs. the turbellarians. Yet it reflects the fact that Neodermata is within free-living flatworms (i.e. turbellaria are paraphyletic). It mentions all traditional taxa that are found in phylogenetic studies (e.g. Laumer et al., 2015). Many of the "in-between" higher level taxa (such as Trepaxonemata etc.) are no longer in WoRMS (probably more user friendly that way). This also means an asymmetry between turbellarians (nine ordines) and Neodermata (superclass with three classes).