The Life History of Nudacotyle novicia Barker, 1916 (Trematoda: Notocotylidae)

Abstract

The greater part of the work on the life history of Nudacotyle novicia was undertaken at the University of Michigan Biological Station during the summers of 1939 and 1940. Several phases of the study lack completeness, but since further work has not been possible the data at hand are being made available. Infection experiments involving the feeding of metacercariae of Cercaria mnarilli Ameel, 1939, to various birds and mammals yielded adult specimens of N. novicia from the bile duct of the meadow mouse, Microtus pennsylvanicus pennsylvanicus. Formerly this species had been reported only from the small intestine of the muskrat, Ondatra zibethica zibethica. Subsequently infection experiments with the snail host provided an insight into the early development of this trematode in the intermediate host. Daughter redia and cercaria.-The daughter redia and cercaria, C. marilli, from the naturally infected snail host, Pomatiopsis lapidaria, have been describedpreviously (Ameel, 1939). The simple sac-like daughter rediae (Fig. 7) occur in the digestive gland of the snail. The body is pigmented and the mouth is terminal, opening immediately into a muscular pharynx. The gut is moderately voluminous and long, extending to the posterior third of the body. It is easily identified under low magnification because of its contents of reddish brown food particles. There seemed to be a relatively small number of daughter rediae per snail. Of a collection of ten infected snails, the number of rediae recovered ranged from 8.to 39 with an average of 24. C. marilli (Fig. 8) is a trioculate monostome cercaria which occurred in 1.2 per cent of the snails collected at Ann Arbor, Michigan, and in 55 per cent of the snails collected near Marion, Iowa. Both body and tail are capable of considerable extension and contraction. Living cercariae under a supported cover glass measured as follows: body extended, 0.42 mm; contracted, 0.21 mm; tail extended, 0.56 mm; contracted, 0.28 mm. Naturally emerged cercariae have three eyespots but most of the immature cercariae lack the median eyespot. The body is opaque and is filled with brown pigment granules and cystogenous cells packed with rod-like cystogenous material. Spineless posterolateral locomotor organs are present. C. marilli resembles the cercaria of Quinqueserialis quinqueserialis (Barker and Laughlin) described by Herber (1942). However, the excretory concretions in the excretory bladder of this species are small but numerous, but those of C. marilli are large and relatively few. The rmetacercaria.-When collections of P. lapidaria are placed in small bottles or stender dishes containing water, the cercariae emerge in numbers during the evening, night, and early morning, and encyst after a brief period of activity. Some