| Macrostomorpha | |
|---|---|
| |
| Macrostomum lignano | |
Scientific classification 
| |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Platyhelminthes |
| Subphylum: | Rhabditophora |
| Subclass: | Macrostomorpha Doe, 1986 |
| Subordinate taxa | |
| |
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.[1] Macrostomorpha constitute a basal group in Rhabditophora, showing such plesiomorphic condition as entolecithal eggs and spiral cleavage.[2] Another trait found among members of the clade is presence of hard stylet in the male copulatory organ.