The life history of Scaphiostomum pancreaticum McIntosh, 1934 (Trematoda: Brachylaemidae)

Abstract

The life cycle of the brachylaemid trematode Scaphiostomum pancreaticum McIntosh, 1934, was completed experimentally in the laboratory. Eggs were obtained from trematodes removed from naturally infected Tamias striatus. Eggs are mature when laid and hatch naturally only after ingestion by a snail. In vitro hatching and subsequent examination of the miracidium was accomplished in snail gastric juice. Sporocysts developed in Anguispira alternata and cercarial emergence began 129 days after infection. Metacercariae developed in the kidney of A. alternata, Triodopsis albolabris, and Haplotrema concavum and were infective to the chipmunk after 5 months, and ovigerous adults were obtained in 30 days. This is the first description of the life cycle of a member of this genus.

The genus Scaphiostomum Braun, 1901 (Trematoda: Brachylaimidae): A systematic review and description of Scaphiostomum palaearcticum n. sp.

“…Scaphiostomum pancreaticum McIntosh, 1934: a parasite of the pancreatic ducts of rodents (Sciuridae: Tamias striatus (Linnaeus, 1758)) in Michigan and Ontario (North America) (McIntosh, 1934;Jensen, 1972); this species uses snails of the species Anguispira alternata (Say) (Helicidae) as first intermediate host and A. alternata, Triodopsis albolabris (Say) and Haplotrema concavum (Say) (Helicidae) as second intermediate host (Jensen, 1972).…”

“…Hosts: the definitive hosts of both are rodents; S. pancreaticum has been found only in a sciurid, Tamias striatus (Sciuromorpha), whereas adults of the Balearic form seem to be less specific, parasitizing free-living (non-commensal) murids, Mus spretus and Apodemus sylvaticus (Myomorpha); the difference in the intermediate hosts is also worth mentioning; none of the North-American species of snails mentioned by Jensen (1972) live on the Balearic Islands or in the circum-mediterranean region; different authors (Wright, 1960(Wright, , 1966Odening, 1964;Macko, 1983) have already referred to the marked relationships between molluscs and digeneans and to the consequent need to consider as different species those digenean species which use different molluscs in different geographical regions, even when the adults appear to be morphologically indistinguishable;…”

Tinamutrema Canoae N. Gen. Et N. Sp. (Trematoda: Digenea: Strigeiformes: Brachylaimidae) in Crypturellus Cinnamomeus (Aves, Passeriformes, Tinamidae) From the Area De Conservación Guanacaste, Costa Rica

“…Species for which life cycles are known develop in both aquatic and terrestrial gastropod or lamellibranch mollusks. Cercariae develop in branched sporocysts, and cercariae either remain in the sporocyst (Krull, 1935) or infect other mollusks of the same or different species (Joyeux et al, 1932;Krull, 1934Krull, , 1935Reynolds, 1938;Alicata, 1940;Pavlov, 1946;Ulmer, 1951aUlmer, , 1951bTimon-David, 1959;Jensen, 1972). The definitive host, therefore, must consume mollusks for the life cycle to be completed.…”