الفهرس 
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Abstract
Four mutelid species (Mutela dubia, M. rostrata, Chambardia
rub ens and C. letourneuxi) were collected from Benha region
(Qaluobiya Governorate), Egypt from winter to autumn 2017 to
elucidate their taxonomic status based on morphology and molecular
technique as well as exploring their reproductive biology.
Morphology and morphometric analysis of the shells (length, width,
height, mantle edge, adductor muscle scar width, height asymmetry,
hinge thickness, shell shapes, shell thickness, mean height and width
indices) had showed differences between all species under
investigation.
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All species under investigation were dioecious except for M.
rostrata that showed hermaphroditism In some specimens. In
addition, they incubated eggs and lasidia only in the inner
demibranch. Oogenesis is divided into oogonia, previtellogenic,
vitellogenic and postvitellogenic oocytes, while the spermatogenesis
differentiated into spermatogonia, spermatocytes, spermatids and
spermatozoa. Sperm morulae were detected only in C. rubens.
Reproductive cycle included four stages started with developing
stage, followed by ripe (mature) then spawning stage and ended with
spent stage. M. dubia and M. rostrata are considered as braditictic
species while C. rub ens is a tachitictic one.
Examinations by light and scanning electron microscopes revealed
that the eggs of species under investigation had brown color and
spherical shape with thin vitelline coat and the egg membrane of M.
dubia had many folds on the surface, while it was nearly wrinkled in
case of M. rostrata and smooth without any folds in case of C.
rubens. Transmission electron microscopical studies showed that the