Acavoidea
Helicophanta gloriosa
The Acavoidea are a superfamily of the suborder of terrestrial snails ( gastropod ). There are mainly usually relatively large snails. The current distribution suggests that their development and Radiation in the late Mesozoic era occurred before the geological continent Gondwana broke up into the present continents.
Features
The dextral housing are medium to rather large. The housing shape varies from hochkonisch to strongly flattened. Also, the embryo already Alwin Dungen are relatively large. In many forms the mouths are strongly modified (for example sharply lowered, folded edges, greatly enlarged, etc.). However, there are no teeth exist, and only very rarely slats. The jaws are aulacognath, that is, thin, smooth or only weakly vertically striped. Occasionally, a central projection is available. The hermaphrodite genital apparatus is usually a relatively simple structure without attachments. Only a few forms form of a flagellum, a blind sac of the penis ( the cecum ) or a vaginal appendix. The inside of the penis is structured complex. The group is generally characterized by extremely large egg size.
Geographical distribution
The representatives of the Acavoidea are located in South Africa, Madagascar, Seychelles, Sri Lanka, Australia, including Tasmania, New Guinea and South America. The distribution suggests that the development and initial radiation from decay of geological Gondwana took place. The disintegration of Gondwana began in the Lower Cretaceous, in the Upper Cretaceous broke off the last land routes to Africa.
System
The superfamily is divided by Bouchet & Rocroi (2005) in six families
- Acavidae Pilsbry, 1895
- Caryodidae Conolly, 1915
- Dorcasiidae Conolly, 1915
- Macrocyclidae Thiele, 1926
- Megomphicidae H. B. Baker, 1930
- Strophocheilidae Pilsbry, 1902
Schileyko (1998 ) divides the superfamily also in six families: Acavidae Pilsbry, 1894, Caryodidae Conolly, 1915, Clavatoridae Thiele, 1926 Dorcasiidae Conolly, 1915, Macrocyclidae Thiele, 1926 Sculptariidae Degner, 1923 Sculptariidae be of Bouchet & Rocroi (. 2005) provided superfamily Plectopyloidea that Clavatoriidae be treated as a synonym of Acavidae. The Strophocheilidae are at Schileyko (1998 ) has its own superfamily with two families.