A new gymnophallid metacercaria [Digenea] in Nacella [P.] magellanica and N. [P.] deaurata [Mollusca, Patellidae] from the Beagle Channel, Tierra del Fuego, Argentina

A new metacercaria (Digenea, Gymnophallidae) parasite of limpets Nacella (P.) magellanica and N. (P.) deaurata from Isla Conejo Beagle Channel (Tierra del Fuego, Argentina) is described and illustrated. According to the evaluation of characters of the family Gymnophallidae proposed by Ching (1995) the metacercariae can be included in the genus Lacunovermis Ching, 1965. The presence of a ventral pit, a wide genital pore, lateral papillae of oral sucker and broad, multipointed spines within tegumental pits confirm this inclusion. The new metacercariae differ in every measurement and ratios of L. macomae (the only valid species for the genus). The metacercaria show high prevalence (40 to 100%) and overdispersed distribution. This is the first record of the genus Lacunovermis for the Subantarctic waters.