Things To Know About the Trematode: Uvulifer ambloplitis

Uvulifer ambloplitis is a trematode (flatworm) which belongs to Family Diplostomidae and Superfamily Strigeoidea. Parasitologists discovered this strigeoid flatworm when they studied the parasites (Uvulifer ambloplitis) that cause black spots in the skin of various fish species. Extensive research revealed that the trematode is also a parasite of kingfishers and fish eating birds that are widely found across the US. The trematode has a spoon-shaped forebody which is separated from the longer hindbody via a slender constriction. The length of the adults ranges from 1.8 mm to 2.3 mm long. (Mehlhorn 2001)

Uvulifer ambloplitis lays its eggs unembryonated; these eggs hatch into miracidia (2nd stage in the life cycle) after 3 weeks. The miracidia swims in the water until they find Helisoma snails, the first host in the life cycle of the parasite. Inside the snail’s body, the miracidia develop into mother sporocyts (3rd stage in the life cycle) which are capable of producing number of daughter sporocyts.

These daughter sporocysts attack the snail’s digestive gland and produce cercariae (4th stage in the life cycle) after around six weeks. The cercariae (singular: cercaria) produced then escape from the mollusk’s body via the tissues. They then swim in the water until they locate their second host, which is a centrarchid fish. They first drop their tails before penetrating the skin of the fish. When the cercariae reach the dermis of the fish, they metamorphose into neascus metacercariae. These metacercaria then secrete a fragile, hyaline cyst wall covering them. The fish response against the neascus is melanin deposition in the dermal region where the metacercariae are embedded. Extreme infection results in more deposition of melanin and more black spots. Fishermen usually discarded them as sick fishes and not worthy to eat and to sell in the market. Kingfishers get infected if they eat the fishes containing the neascus metacercariae. It takes between 27 and 30 days before Uvulifer ambloplitis becomes a completely matured flatworm. (Mehlhorn 2001)

Other species belonging to genus Uvulifer have been found in various fishes. Their life cycles are similar to Uvulifer ambloplitis life cycle. The neascus larva of Uvulifer ambloplitis and other species are hard to differentiate because they are very similar morphologically. Identifying individuals as belonging to a particular species usually requires waiting until they reach their adult stages. However, the larva could be temporarily identified as Neascus trematodes. (Mehlhorn 2001)


Mehlhorn , Heinz, P M Armstrong. 2001. Encyclopedic Reference of Parasitology. Published by Springer.