Hydrocenidae
Cattaro hollow house ( Hydrocena cattaroensis )
The Hydrocenidae are a family of snails from the superiority of the Neritimorpha ( subclass Orthogastropoda ). It is the nominotypical and only family of the superfamily Hydrocenoidea. There are very small forms, which often live in moist habitats near the coast in moist ravines or in caves. The family is probably already present in the Upper Cretaceous.
Features
The family is characterized by small, roundish - ovate housing, few possess, convex whorls. A spiral sculpture may be present or absent. The mouth is entire, rounded - ovate and angled at the top. The mouth rim is indeed strongly developed but not thickened, and the outer edge is not handled. The spindle is short and slightly concave. The spindle height is slightly thickened and turned over the navel; therefore a gap navel missing. It is a calcareous filler cap provided, which is supported on the rear part of the foot. He is semi-circular with strong growth lines and a nucleus at the lower left margin. On the inside of the lid a strong, tapered extension ( apophysis ) is present. The gills are degenerated, breathing takes place through the tissue lining of the mantle cavity. The animals are dioecious.
Geographical distribution and habitat
The representatives of the family are land animals that live in moist habitats near the coast. Some species live further away from the coast and at a higher altitude in the mountains. Some species have become typical caveman.
Taxonomy and systematics
The taxon was erected in 1856 by Franz Hermann Troschel. It currently contains about seven genera:
- Genus Chondrella Pease, 1871
- Genus Georissa Blanford, 1864
- Genus Hydrocena Küster, 1844
- Genus Omphalorissa Iredale, 1933
- Genus Sinicena Egorov, 2003 ( nom. nov. Lapidaria per Kang, 1986)
The genus yet identified at Wenz Georissops is today partly as a subgenus of Georissa, z.T. regarded as a synonym of Georissa.
Phylogeny
According to the phylogenetic analysis of Architaenioglossa by Kano et al. (2002 ) form Hydrocenidae, Helicinidae, Neritiliidae, Phenacolepadidae and Neritidae a clade that is the sister group of the Neritopsidae. Within the clade Helicinidae, Neritiliidae, Phenacolepadidae and Neritidae the family Hydrocenidae basal faces the other groups. Of these four groups and Phenacolepadidae Neritidae on one side and Helicinidae Neritiliidae and on the other hand are in turn sister groups. The authors also transferred Schwardtina cretacea ( Swap, 1856) from the Upper Santonian /? Lower Campanian ( Upper Cretaceous ) from Hungary to Hydrocenidae family. The genus was originally provided by Bandel & Riedel ( 1994) with a question mark in the Neritidae family. The protoconch of Schwardtina cretacea is very similar to the protoconch the genus Hydrocena. The protoconch of Hydrocena is typical of a non- planktotrophe development, ie the embryo fed on Nähreiern or albumin reserves in the egg capsule. Therefore, on the Embryonalgehäuse immediately follows the Teleoconch and just not Larvalgehäuse. According to the revised interpretation of the fossil record of Schwardtina Hydrocenidae family begins in the Upper Cretaceous. The eponymous genus Hydrocena knows you saved from the Tortonian ( Miocene, Neogene ).