Subterranean aquatic planarians of Sardinia, with a discussion on the penial flagellum and the bursal canal sphincter in the genus Dendrocoelum (Platyhelminthes, Tricladida, Dendrocoelidae)

The paper provides the first detailed account on the taxonomic richness of the
subterranean freshwater triclads from Sardinia, including the description of four new
species for the genera Dendrocoelum and Phagocata. New records for Dugesia benazzii,
Dugesia sp., Crenobia alpina, and Phagocata sp. are also reported. The three new species
of Dendrocoelum are the first reported for the island of Sardinia. These species display a
bursal canal sphincter and a large adenodactyl with a characteristic anatomy with a zone
of fine circular muscle fibers running through the mesenchyme of its papilla. A detailed
analysis of the structure of the penial flagellum in the genus Dendrocoelum highlighted six
main conditions, some of which have not been previously reported, in regard to the
histology of the tip of the penis papilla and the extent of its inversion. The new species of
Phagocata represents the first species recorded from Italy and the first anophtalmous
species reported from Europe.