Leptoxis compacta
| Leptoxis compacta | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Leptoxis compacta |
||||||||||||
| Systematics | ||||||||||||
|
||||||||||||
| Scientific name | ||||||||||||
| Leptoxis compacta | ||||||||||||
| ( Anthony , 1854) |
Oblong rocksnail ( English oblong rocksnail ) is a Süßwasserschneckenart . It is endemic to the Cahaba River , a tributary of the Mobile River in the US state of Alabama . It has not been found in a period of more than 70 years and formally declared extinct in 2000. Living specimens were not discovered again until May 2011.
features
The snail shell of Leptoxis compacta is egg-shaped to conical, smooth, thick-walled and yellowish-green. The thread rises at an obtuse angle and has about five turns that are almost flat. The basic turn, which takes up the snail's body, is wide, only slightly twisted and has three very dark bands. The penultimate turn has only two dark bands, of which the lower one is partially or almost completely covered by the notch (suture) to the next turn. The top turn only has a hairline black line. The opening of the snail shell is relatively wide, whitish on the inside and also striped. The central spindle (Columella) is strongly notched, the base is uniformly rounded and has no cavity. The width of the snail shell is about 10 mm, the height about 15 mm. The height of the opening is about 7.5 mm.
Most of the wild specimens found in 2011 had purple pigmentation on the notch of the columella, while this feature could not be observed in the young animals that were later raised in captivity. Juvenile Leptoxis compacta have a small thorn (carina) on the main turn, which is lost in adult individuals.
The body surface is yellow with black flecks. Black pigmented bands run in the middle of the trunk and on both eyes. The band pattern is identical to that of the Leptoxis ampla found in the same location . The coloring pattern and the presence of an eye stalk (Pedunculus) distinguish Leptoxis compacta from the snails of the genus Pleurocera , which also occur in the same location and which conchologically (in terms of the shell) resemble Leptoxis compacta most.
Way of life
Leptoxis compacta lives on the upstream side of sandbanks .
The female specimens of Leptoxis compacta laid 0.3 mm diameter eggs individually or in short rows within three days of being transferred to captivity. The average length of the egg lines was 1.57 eggs, a maximum of 3 eggs were counted in one line. No eggs were laid at water temperatures above 29 ° C.
History of discovery, distribution and endangerment
The first description of oblong rocksnail was made in 1854 by John Gould Anthony under the name Melania compacta .
The previously documented distribution area reached from the lower reaches of Buck Creek in the south of the Valley and Ridge zone of the Appalachian Mountains to Centerville in Alabama. The greatest distribution was found in the area of the Lily Shoals sandbanks in the middle reaches of the Cahaba River. The cause of the decrease in the population of Leptoxis compacta documented from 1935 onwards is unknown. In addition to the originally already small distribution area, sewage from regional mines and the metropolitan area of Birmingham are considered to be the most likely cause. The last documented find dated to the year 1933. In the course of several systematic investigations of the river course in 1992, 2005 and 2008 Leptoxis compacta could not be detected. Leptoxis compacta was declared extinct by the International Union for Conservation of Nature and Natural Resources (IUCN) in 2000 . It was considered the only extinct endemic of the Pleuroceridae family in the Cahaba River.
As part of an expedition to record the biodiversity of snails in the catchment area of the Mobile River in the US state of Alabama - after almost 80 years without a find - in May 2011, specimens of were found again in a very short section of the Cahaba River not far from the inlet of Shades Creek Leptoxis compacta found. This rediscovery was published in PLoS ONE in August 2012 . In their work, the authors come to the conclusion that the local, narrowly restricted existence of this species puts it at risk of permanent extinction in the event of a single environmental disaster , and they discuss whether the chances of survival can be improved by multiplying the snails in the laboratory and reintroducing them to the entire original range.
The scientific publication of the rediscovery was received by journalists and popular science, especially in relation to the general extinction of species .
See also
- Lazarus effect , rediscovery of a species believed to be extinct
Individual evidence
- ↑ a b c d e f g h Nathan V. Whelan, Paul D. Johnson, Phil M. Harris: Rediscovery of Leptoxis compacta (Anthony, 1854) (Gastropoda: Cerithioidea: Pleuroceridae). PLoS ONE 7 (8): e42499. doi: 10.1371 / journal.pone.0042499
- ^ A b J. G. Anthony : Descriptions of new fluviatile shells of the genus Melania Lam., From western states of North America . In: Annals of the Lyceum of Natural History of New York Volume 6, 1854: 80 -130. P.122 . Plate III, Figure 22
- ↑ Leptoxis compacta in the Red List of Threatened Species of the IUCN 2012.1. Posted by: AE Bogan (Mollusc Specialist Group), 2000.
- ↑ Julia Merlot: Student finds missing snail. In: Spiegel Online , August 13, 2012
- ↑ Evelyn Lamb: Rumors of the Oblong Rock Snail's Demise Were Somewhat Exaggerated. In: Opinion, arguments & analyzes from the editors of Scientific American . August 8, 2012
