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Order Prolecithophora Karling, 1940


Mostly small turbellarians, with sac-like gut and either a pharynx plicatus or pharynx variabilis. Germinal tissue follicular or compact, eggs ectolecithal, ovary and testes compact or diffuse, and vitellaria diffuse; male pore anterior to female but opening into a common pore. Free-living and symbiotic, freshwater and marine.


COMBINATA - With tubular pharynx plicatus. With a common oral-genital opening, oocytes and vitellaria not fully separated, often with female accessory organs and a vaginal pore.

SEPARATA - Pharynx not tubular, usually variabilis. With separate mouth and genital openings. Ovary and vitellaria fully separate, without female accessory organs.


For convenience the Combinata is divided into two groups which probably have little phylogenetic relevance.


Opisthoporata (Combinata)
Proporata (Combinata)


Baicalarctiidae Friedmann, 1926 (Separata)
Multipeniatidae Nasonov, 1927 (Separata)
Plagiostomidae Graff, 1908 (Separata)
Ulianiniidae Karling, 1963 (Separata)


A clear concept of this group is lacking. Ax (1984) preferred to leave the group incertae sedis after the work of Ehlers (1984). Karling (1940) gave some perspective of the group as it was then viewed.

This group is not well defined and ongoing research is changing and will likely continue to change taxon bounderies. Timoshkin (1986), for example, suggested removal of the Baicalarctiidae from the Separata and incorporating this taxon as a subfamily Baicalarctiinae within the Protomonotresidae with the addition of a new genus Friedmaniella Timoshkin and Zaborskaya, 1985. The remaining genera he included in the subfamily Protomonotresinae, but removed Prolecithoplana to its own family Prolecithoplanidae. As well he suggested that Acanthiella Rieger and Sterrer, 1975 be placed in a new family Acanthiellidae. Also Hyra (1993) claimed the symbiotic groups Urastomidae and Hypotrichinidae (which correctly should be Genostomidae since the type genus is Genostoma and not Hypotrichina) should be removed to the Rhabdocoela. Furthermore, Jondelius (in press) erected a new family Torgeidae (Separata) with "gonopore separate from the mouth, in mid-body" for his new genus Torgea Jondelius, in press.

Order Prolecithophora