(No common name)

ORDER

Amphilinidea

FAMILY

Amphilinidae

TAXONOMY

Monostomum foliaceum Rudolphi, 1819, Italy.

OTHER COMMON NAMES

None known.

PHYSICAL CHARACTERISTICS

Body monozoic, dorso-ventrally flattened, oval or leaf-shaped in outline, 1–2.6 in (28–65 mm) long and 0.67–1.2 in (17–30 mm) wide. Anterior end pointed, with slightly expressed apical invagination. Uterine orifice situated in anterior end. Orifice of ejaculatory duct on posterior end. Vaginal pore postero-lateral, at some distance from male pore.

DISTRIBUTION

Europe and Siberia.

HABITAT

Adults are parasitic in the body cavity of sturgeons (Acipenser sturio, A. nudiventris, A. ruthenus, A. stellatus, Huso huso, etc.). Larvae develop in freshwater amphipod crustaceans. The macrohabitats of Amphilina foliacea are large rivers in Eurasia. Though it cannot develop in marine amphipods, it can be found also in marine sturgeons (which are anadromous).

FEEDING ECOLOGY AND DIET

Not studied. Apparently absorb nutrients through the tegument.

BEHAVIOR

Nothing is known.

REPRODUCTIVE BIOLOGY

A. foliacea is hermaphroditic. There are no data how often cross-fertilization or self-fertilization may occur. Eggs develop in uterus and are released through its orifice. Each egg contains larva named lycophora. It is not known how eggs pass from the body cavity of the sturgeon into the water. The eggs are swallowed by amphipods (intermediate hosts). The lycophora leaves the egg envelope in the intestine of the intermediate host and passes through its wall into the body cavity. There, it develops into a larva (about 0.16 in [4 mm] long) for some six weeks. Feeding on crustaceans containing fully developed larvae infects sturgeons. Larvae pass through the wall of the stomach into the body cavity. They become mature after six to seven months and live several years.

CONSERVATION STATUS

Not listed by the IUCN.

SIGNIFICANCE TO HUMANS

None known.