Pomatiopsidae
Oncomelania hupensis
Pomatiopsidae is a family of mainly small freshwater snails from the superfamily Rissooidea. The family includes about 170 species. Some of these species are intermediate hosts of the fluke, the causative agent of schistosomiasis, of importance.
Features
The housing of the Pomatiopsidae are small 2.5 to 9.5 mm long (eg Delavaya ), thin - or thick- often colorless, translucent or covered little ornamented with a brown periostracum and. The housing with vaulted whorls vary in shape from ovate - conical to planispiral. The housings are diagnostically without great value. The species of the family possess gills and an operculum, and are dioecious. The gills, an original feature, but can also be strongly degenerated or nearly absent. The animals breathe through the body surface. The reduction of the gills is not limited to terrestrial living forms, but also occurs in purely aquatic living species.
The sperm enters the female oviduct over the spermathekalen channel, which is separate from the opening into the mantle cavity fallopian tubes. The spermathekale channel is the extension of a protrusion of the bursa copulatrix. The males have a simple penis, ie a simple ladder without attachments.
The egg capsules are round and contain a single zygote. The surface of the egg capsules is sticky; therefore, they are covered with mud and detritus.
Geographical distribution and habitat
Pomatiopsidae are common in the tropics and subtropics worldwide. The highest diversity of taxa (Thailand to Japan) to be found in Southeast and East Asia. In addition, there are representatives in Africa, Australia, South America and North America.
Way of life
After copulation and internal fertilization, the eggs are laid singly in the water. The eggs develop in the egg case to a trochophore larva and later to a veliger larva. This leaves the egg membrane so that the veliger larva is the only free-living larval form. The veliger larvae live relatively long in the plankton, which they also feed on. The Larvalgehäuse developed already during the planktonic life phase and before the onset of metamorphosis and the transition to soil life. The adult representatives of Pomatiopsidae live in freshwater, amphibious or even in the country. They feed on algae and detritus, which they graze from the surface of rocks, sediment or other solid reasons.
System
The taxon was erected in 1865 by William Stimpson. It was formerly often made as a family in the Hydrobiidae family. In between, the position has become established as an independent family. The family is currently divided into two subfamilies, the Pomatiopsinae and Triculinae:
- Subfamily Pomatiopsinae Stimpson, 1865 (synonyms: Hemibiinae Heude, 1890; Tomichiinae Wenz, 1938 W Coxiellidae Iredale, 1943; Oncomelaniidae Salisbury & Edwards, 1961; Cecininae Starobogatov, 1983) Blanfordia Adams, 1863
- Cecina A. Adams, 1861
- Coxiella E. A. Smith, 1894
- Fukuia Abbott & Hunter, 1949
- Hemibia Heude, 1890
- Oncomelania Gredler, 1881
- Pomatiopsis Tryon, 1862 - type genus of the family
- Tomichia Benson, 1851
- Subfamily Triculinae Annandale, 1924 Tribus Triculuni Annandale, 1924 ( synonym: Delavayidae Annandale, 1924) Delavaya Heude, 1889
- Fenouilia Heude, 1889
- Tricula Benson, 1843
- Jullienia Crosse & P. Fischer, 1876
- Lacunopsis Deshayes, 1876
- Gammatricula Davis & Davis Liu in Liu & Chen, 1990
- Halewisia Davis, 1979
- Jinghongia Davis in Davis & Kang, 1990
- Neotricula Davis in Davis, Subba Rao & Hoagland, 1986
- Pachydrobia Crosse & P. Fischer, 1876
- Robertsiella Davis & Greer, 1980
- Wuconchona Kang, 1983
Taxon of unknown subfamilies and tribes assignment:
- Rehderiella Brandt, 1974