Haplopharyngida

Haplopharyngida is a taxon of small, free living marine flatworms found in the North Atlantic and the Mediterranean, with only three described species.

Haplopharyngida
Scientific classification
Kingdom: Animalia
Phylum: Platyhelminthes
Class: Rhabditophora
Subclass: Macrostomorpha
Order: Haplopharyngida
Karling, 1974
Subgroups

See text

Systematics

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.[1]

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.[2]

References
  1. Karling, Tor G. (1965). "Haplopharynx rostratus Meixner (Turbellaria) mit den Nemertinen verglichen". Journal of Zoological Systematics and Evolutionary Research. 3 (1–2): 1–18. doi:10.1111/j.1439-0469.1965.tb00424.x.
  2. Egger, Bernhard; et al. (2015). "A Transcriptomic-Phylogenomic Analysis of the Evolutionary Relationships of Flatworms". Current Biology. 25 (10): 1347–1353. doi:10.1016/j.cub.2015.03.034. PMC 4446793. PMID 25866392.


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