Biological and taxonomical studies on a freshwater operculate snail from Assiut province

Abstract

1-The resent investigation deals with the Egyptian freshwater operculate snail belonging to genus Theodoxus (Neritaea), the definition of this prosobtanch species, belonging to family :Neritidae depended mainly on its shell characters. As fat as cart oe ascertained ,

no published work on the soft parts of this local snail has beeh foUnd. Therefore, this study entails the external features of the snail, the functional anatomy of some taxonomically important organs and the detailed functional morphology of its female and male reproductive organs.

2- The snails were collected from different freshwater courses in Assiut governorate.

3- the shell of the adult specimen of the present snail is ye11owish white with zigzag transverse brown or dark brown bands, without clear sculpture and its aperture has two lips without any denticulatlorts. The shell operculum which is D - shaped, has two processes namely; a peg

and a rib. These characters of the shell and its operculum ate in agreement with those previously reported by authors for T. niloticus (Reeve, 1856).

4- The topography and general pattern of the soft parts of this snail are similar to those of other trtembers of the famiiy Neritidae.

5-The macro- and microanatomy of some taxonomically important organs has been studied in detail and the results have been discussed.•