A new operculate genus from East Africa — Elgonocyclus (Mollusca, Cyclophoridae), a preliminary diagnosis

Whilst working through the Ake Holm collection, kindly sent on loan to me from the Naturhistoriska Riksmuseet, Stockholm, by Dr. Ake Anderson, I discovered several lots of minute operculates from various localities on Mt. Elgon and eastern Kenya. These immediately struck a chord of memory and reference to my notes of a visit to the Laboratoire de Malacologie, Museum National de Histoire Naturelle, Paris, in the late 1950’s confirmed that on examination of the types of two supposed species of Trachycystis described from Mt. Elgon by Louis Germain I had commented ‘look very like small operculates and probably conspecific’. I was able to make a direct comparison of the Holm material with these types in March 1982 by kind permission of Dr. Simon Tillier during another brief visit to Paris. This showed that my original impressions were certainly correct and that only one species is actually involved. I have been unable to refer it to any known genus of African operculates nor does it seem to fit into any extra-African genus. I have reached the conclusion that a new genus is needed. Since a detailed study of the minute animal will take a long time and a name is needed for a list of East African non-marine Mollusca to be published soon, and in fact already distributed to a few institutions as a typescript, a preliminary diagnosis is given here to avoid a manuscript name coming into use.