Zospeum tholussum
| Zospeum tholussum | ||||||||||||
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Zospeum tholussum , holotype |
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Zospeum tholussum | ||||||||||||
| Weigand , 2013 |
Zospeum tholussum is a very small, blind species of snail from the family of the dwarf horn snail (Carychiidae) in the order of thepulmonate snail (Pulmonata). It lives in absolute darkness at 980 m below the earth's surface in the Lukina Jama – Trojama cave system in Velebit ( Croatia ).
features
The right-hand winding case is 1.41 to 1.81 mm high (n = 7), the width varies from 0.93 to 1.12 mm. The mouth is 0.44 to 0.54 mm high and 0.38 to 0.46 mm wide. The ratio of case height to case width is between 1.34 and 1.62, and the ratio of mouth height to mouth width between 1.05 and 1.30. There are five to six turns. The second turn is noticeably enlarged and is two thirds to five sixths the height of the third and fourth turns. The spindle is poorly developed, the convolutions are without teeth or folds.
The surface is smooth and shiny. The shell is very thin and fragile. Fresh housings or the housings of animals that are still alive are translucent, pigmentless, housings that are no longer fresh are rather milky-cloudy.
The soft body is also glassy-light, translucent and pigmentless. The antennae are conical, eyes are missing. Only the intestinal contents are brownish and shine through the soft body and shell.
Similar species
The DNA barcode is closest to Zospeum pretneri Bole, 1960 (approx. 5.6%), but is well above the value (3.2%) that is usually sufficient to distinguish species of the genus Zospeum by molecular genetics. In the general shape of the housing, Zospeum tholussum is reminiscent of larger specimens of Zospeum amoenum (Frauenfeld, 1856). Zospeum tholussum differs from this species, however, in the strongly inflated shape of the second turn. Zospeum amoenum , on the other hand, has a weak, but definitely present, spindle fold. The genetic p-distance of the DNA barcode is 11.7% to 12.1%.
In the Lukina Jama – Trojama cave system there is a second, not yet described species of Zospeum . This species differs from Zospeum tholussum by the lack of the typical, inflated second turn, in the general shape of the housing, by a well-developed mouth tooth and the clearly stronger spindle fold. Since no living specimen has been found, the species has not yet been described.
Geographical distribution and habitat
The only living specimen was found in a large cave chamber (85 m long, 70 m wide) at a depth of 980 m. In the cave chamber lay a great deal of small and large boulders and sand; a small trickle flowed near the point of discovery. The air temperature was 3.3 to 3.5 ° C, the water temperature 5.1 ° C and the humidity 100%. Empty shells were found in the cave from a depth of 800 m to 980 m. The casings were all on layers of cave clay. The first 200 m of the entrance area of the Lukina Jama cave system are covered with snow and ice to varying degrees throughout the year. So far the species is only known from the Lukina Jama cave system.
Way of life
The animals move only a few millimeters or centimeters a week. They feed on the growth on the loamy floors of the caves. Most of the empty enclosures were found in maze-like pasture structures. Such pasture structures have also been found in caves in northern Spain, in which species of the genus Zospeum also live. The species spreads passively through flowing water or through animals living in caves.
Taxonomy
The taxon was first described in 2013 by Alexander Weigand in the journal Subterranean Biology . The species is so far only known from the type locality. The species name is derived from the Latin word tholus , which means dome or cathedral. The species name alludes to the heavily inflated, dome-like second turn.
Media reception
In 2014 the species was voted into the top ten newly described species (from the previous year). The species impressed the members of the selection committee because of its spirit-like appearance, since the casing and the body are without pigments. In the media, these top ten newly described species are often presented as the bizarre or even most bizarre new species (e.g. the Spiegel or Focus).
supporting documents
literature
- Alexander M. Weigand: New Zospeum species (Gastropoda, Ellobioidea, Carychiidae) from 980 m depth in the Lukina Jama – Trojama cave system (Velebit Mts., Croatia). Subterranean Biology 11, 45-53. 2013 doi : 10.3897 / subtbiol.11.5966 abstract
Individual evidence
- ↑ Domed Land Snail: Looks Ghostly, Moves Slowly Top 10 New Species of 2014 Website of the International Institute of Species Exploration
- ↑ Spiegel-online
- ↑ Page no longer available , search in web archives: The "Zospeum tholussum" snail, which is transparent and has no eyes, was discovered in Croatian caves. on www.focus.de
