Macrostomorpha is a clade of free living

flatworm Platyhelminthes (from the Greek language, Greek πλατύ, ''platy'', meaning "flat" and ἕλμινς (root: ἑλμινθ-), ''helminth-'', meaning "worm") is a Phylum (biology), phylum of relatively simple bilaterian, Segmentation (biology), ...

s in the group

Rhabditophora Rhabditophora (from ''rhabdito''-, rhabdite + Greek -φορος ''phoros'' bearer, i.e., "rhabdite bearers") is a subphylum (previously a class) of flatworms. It includes all parasitic flatworms (clade Neodermata) and most free-living species ...

Description

Species of Macrostomorpha are characterized by having the necks of the viscid gland and releasing gland emerging in a common collar of anchor cell microvilli. They also gave aciliary speratozoa and a pharynx of the simplex coronatus type. Macrostomorpha constitute a basal group in Rhabditophora, showing such plesiomorphic condition as entolecithal eggs and spiral

cleavage Cleavage may refer to: Science * Cleavage (crystal), the way in which a crystal or mineral tends to split * Cleavage (embryo), the division of cells in an early embryo * Cleavage (geology), foliation of rock perpendicular to stress, a result of ...

. Another trait found among members of the clade is the presence of hard stylet in the male copulatory organ.

Phylogeny and systematics

Originally the clade Macrostomorpha was divided into two groups: Haplopharyngida (containing a single family, Haplopharyngidae) and Macrostomida (containing the families Macrostomidae, Microstomidae and Dolichomacrostomidae). However, molecular studies revealed that these groups are not monophyletic. The current phylogenetic classification is presented in the following tree:

References

{{Taxonbar, from=Q3275008 Turbellaria Rhabditophora