NOTES ON THE LIFE-CYCLE OF AZYGIA ACUMINATA GOLDBERGER, 1911 (AZYGIIDAE-TREMATODA)

¹ Marine Biological Laboratory, Woods Hole, Mass.

1. Stages in the life-cycle of Azygia acuminata are described and figured. Cystocercous cercariae develop from rediae in the snail, Campeloma decisum. The cercaria is morphologically distinct from other described cystocercous cercariae. Rediae are similar to the same stage described for other members of the genus, but are unique since they develop in the uterus of female Campeloma decisum.

2. The excretory system of the cercaria is complex, showing a formula of 2 (11 x 32) or 704 flame cells for the distome portion and 2 (5 x 32) or 320 flame cells in the tail. The excretory formula of the cercariae is thus 2 (16 x 32) or 1,024 flame cells.

3. Attempts to experimentally infect small snails, taken from the uterus of a Campeloma decisum, by feeding them eggs of A. acuminata were not successful.

4. Various small fishes were utilized as paratenic hosts by the young distomes. Infections in sticklebacks, Eucalia inconstans, and small eels, Anguilla rostrata, resulted in more active and vigorous worms than did infections from other paratenic hosts.

5. The variation that normally occurs in members of the genus Azygia due to development in a wide variety of hosts is not known. Consequently diagnostic characters of mature worms can not be relied on to distinguish species. On the basis of this report the suppressed species A. acuminata is regarded as a valid species and should be retained in the genus Azygia.

6. A. acuminata, previously reported only from Amia calva, was found occurring naturally in bullheads, Ameiurus nebulosus, blue gill sunfish, Lepomis macrochirus, and chain pickerel, Esox niger, from Santuit River, Barnstable County, Cape Cod, Massachussetts. Experimental infections were also obtained in these fishes and in the yellow perch, Perca flavescens.

7. A revised key for the genus Azygia is presented, listing the recognized species and the described cercarial stages.