A Species of Tetrahymena from the British Garden Slug Milax budapestensis

Abstract

HISTOPHAGOUS species of the ubiquitous holotrich genus Tetrahymena (Ciliata: Hymenostomatida) have been reported from the body spaces and tissues of a variety of vertebrate and invertebrate organisms1. Slugs and snails have been named as hosts in a dozen widely scattered and usually very brief reports published during the past 30 years, the molluscs having been collected in South Africa, the Congo, Poland, Nova Scotia, and from sites in California, Oregon, Virginia, and Illinois in the U.S.A. In work by one of us (A. C. S.) on osmotic relations in gastropods, a small (about 40µ long) ciliated protozoon was detected in a blood sample withdrawn from one of the common British garden slugs, Milax budapestensis (Hazay, 1881), collected in the University of Exeter greenhouse. Subsequent examination of additional specimens of this species of keeled slug revealed similar infections; the ciliates were apparently present throughout the alimentary tract and in the liver, although not occurring in great numbers, Study of the protozoon by silver impregnation2 and other techniques made possible its identification as a strain of Tetrahymena limacis (Warren, 1932) Kozloff, 1946, in agreement with the careful redescriptions of this species published by Kozloff3–5.