ウスベニギセルガイの産卵と発育過程

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Although the clausiliid land snails are generally treated as ovo-viviparous hermaphrodites and directly lay the juveniles, it is known that some species of this group are oviparous and lay the eggs. Miyazaki (1966) observed that Tyrannophaedusa mikado produced the eggs and reported its copulating and spawning behaviors. We had an opportunity to observe the spawning of another oviparous species, Tyrannophaedusa (Ventriphaedusa) aurantiaca ; in this paper we reported on the spawning and growth rate of this oviparous species comparing with those of the above mentioned T. mikado. The present species was collected from Futami, Mie Pref., Honshu and has breeded in our laboratory in petri-dish of 15 cm in diameter. Each spawning and growth stages are chronologically arranged as follows : August 10, 1969 the specimens was collected in the field. 40 days September 18, 1969 eggs are laid down (7 in number). 13-14 days September 30- Oct. 1, 1969 hatched out. 84-85 days December 23, 1969 matured. In the laboratory, the copulating snails had never been observed. Concerning the data of T. mikado, it took about one to two months to lay the eggs after the copulation (Miyazaki, 1966) ; therefore it is considered that the copulation of the present specimens had finished in the field before we collected. The egg is almost round in shape and white in color, and has a rather thick calcareous egg-shell measuring about 2 mm in diameter. Hatched out juvenile has a shell of about 2 volutions of 2.0-2.5 mm in shell height. It takes 84 days after hatching to make inner plicae and thickened periphery of the shell aperture, which are treated as the indicators for the maturation of the clausiliid snails.
日本貝類学会の論文
1970-05-15

ウスベニギセルガイの産卵と発育過程

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