Haplopharyngida

Haplopharyngida is a taxon of small, free living marine flatworms found in the North Atlantic and the Mediterranean, with only three described species.
Anatomy.
Subterminal mouth leads to the simple pharynx, which subsequently continues as an intestine with terminal anal pore. A short retractable proboscis is present anteriorly to the pharynx. Variable number of glands producing rhabdites open at the surface of proboscis. Nervous system built similarly as in Macrostomida. Haplopharyngida are hermaphroditic, with separate male and female gonopores. Male copulatory organ is equipped with hard, sclerotised stylet and set of needles.
Reproduction and development.
Copulation lead to the internal fertilization. Egg is entolecithal and show spiral cleavage pattern.
Systematic position.
Haplopharyngida are considered as a sister group of Macrostomida, together they are grouped in the class Macrostomorpha in the clade Rhabditophora.