On the Excretory System and Life History of Lecithodendrium chilostomum (Mehl.) and other Bat Trematodes, with a Note on the Life History of Dicrocoelium dendriticum (Rudolphi)

Abstract

1. The life history of Lecithodendrium chilostomum has been established; C. Lecithodendrii chilostomi penetrates a second intermediate host, the larva of Phryganea grandis, and unlike other stylet cercariae does not encyst, but feeds and grows in the host tissue as a mobile metacercaria. During pupation of the host in the following year these mobile forms migrate from the abdominal segments of the larva to the thorax, where they then encyst in the thoracic muscles in which they are also found in the imago. The largest metacercariae and the excysted worms are typical early adult Lecithodendrium chilostomum. No case of progenesis in the metacercaria was found.2. It is estimated that the maximum swarming of the cercariae probably occurs during July, when first penetration of the intermediate host takes place. Subsequent diminished swarming and penetration proceed until November. The life of the larval trematode as a mobile metacercaria is approximately 8 months; the imagines of Phryganea grandis emerge during May and June, the infective period for the final host.3. The metacercariae are not distributed throughout the body cavity of their larval host, but the majority are confined to the three posterior segments.4. Limnophilus rhombicus may also serve as a second intermediate host, but the infection is very light and the metacercariae do not encyst during pupation of this host.5. The excretory system has been determined in all stages of Lecithodendrium chilostomum; it is of the 2 (6 × 2) type. The occurrence of this type of system in other groups of cercariae is reviewed and since it is found in several widely separated families, it is suggested that its presence does not necessarily imply relationship, but is due to convergence.6. The life histories of the following bat trematodes are indicated: Lecitho-dendrium lagena, Plagiorchis vespertilionis and Crepidostomum moeticus.7. The life history of Dicrocoelium dendriticum is discussed.