Acmella nana
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Acmella nana |
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| Vermeulen , Liew & Schilthuizen , 2015 |
Acmella nana is a terrestrial snails art from the family of assimineidae that the Caenogastropoda is expected. With a shell height of 0.60 to 0.79 mm, it is currently (2015) the smallest snail living on land. So far it is only known from empty housings.
features
The conical, right-hand wound and very small cases are 0.60 to 0.79 mm high and 0.50 to 0.60 mm wide, with a height / width index of 1.00 to 1.35. The outer line is straight to slightly curved outwards. The apex is bluntly angled. The housings have 2 7/8 to 3 7/8 moderately convex turns, which are occasionally also slightly shouldered. The mouth is egg-shaped in plan view with a slightly concave to slightly convex parietal edge. The transition from the parietal margin to the basal margin is rounded to slightly blunt angled. The mouth plane is inclined to the axis of the coil and jumps back at the basal margin. The coil height varies from 0.30 to 0.37 mm, the coil width from 0.26 to 0.30 mm. The mouth edge is only slightly turned over and thickened on the outside of the turn; the envelope increases towards the edge of the spindle. The navel is open and very narrow.
The whitish skin is thin and translucent, the surface is shiny. On the surface there is a clear spiral sculpture that occasionally intersects with faint, radial growth strips. The growth strips can also be made somewhat stronger at irregular intervals. The spiral lines are tightly packed at regular intervals, separated from each other by narrow longitudinal pits.
The species is only known from empty cases.
Similar species
Acmella nana is very similar to the species Acmella caelata Vermeulen & Junau, 2007 by Sarawak, but its shell is significantly wider (0.7 mm in Acmella caelata to 0.50 to 0.60 mm in Acmella nana ). The casing of Acmella caelata is significantly higher or larger (with 3 1/8 to 3 3/8 turns, Acmella caelata is 0.80 to 0.95 mm high compared to 0.60 to 0.75 mm for Acmella nana ).
Acmella ovoidea is also larger and slightly wider in thread whencomparingjuvenile specimens of the same size with adult specimens of Acmella nana . Acmella nana also has a more powerful spiral sculpture.
Geographical distribution and habitat
Acmella nana is endemic to Borneo . In Sabah it comes in the valley of the Pinangah near Batu Urun (= Bukit Sinobang), in the valley of the Sepulut near Gua Pungiton and Gua Sanaron in the Interior Division and in the valley of the Kinabatangan near the Gomantong caves , 30 km south of Sandakan in the Sandakan district in front. Other sites are in Sarawak and in East Kalimantan ( Malaysia ).
The species was found in (already disturbed) original tropical forests on chalky subsoil from sea level to 500 meters above sea level. Since the housings were obtained from soil samples, nothing can be said about the exact habitat and way of life of the species.
Taxonomy
The taxon was published in November 2015 by Jaap J. Vermeulen , Thor-Seng Liew and Menno Schilthuizen . The holotype comes from a soil sample that Vermeulen had collected in a crevice filled with soil in the western part of a quarry near the Niah Caves in the Miri district in Sarawak . It is kept in Naturalis , the natural history museum of the Netherlands, under the number RMNH.5003950. The species name nana comes from the Latin nanus for "dwarf" and indicates the small housing size.
Reception in the press
Immediately after publication (November 2, 2015) the press picked up on the news. The new species even made it to the CBSNews, International Business News, Newsweek, Sci-News, or Washington Post websites on the same or the following day, to name just a few. However, the headlines shoot z. Sometimes over the target (... the smallest snail in the world ...), because the smallest snail in the world to date Ammonicera minortalis Rolán, 1992 is a marine snail with a shell height of only 0.32 to 0.46 mm. Wired.de (researchers discover the smallest snail in the world on Borneo) shows the smallest land snail Angustopila dominikae to date instead of Acmella nana .
supporting documents
literature
- Jaap J. Vermeulen, Thor-Seng Liew, Menno Schilthuizen: Additions to the knowledge of the land snails of Sabah (Malaysia, Borneo), including 48 new species. ZooKeys 531: 1-139 (2 Nov 2015) doi : 10.3897 / zookeys.531.6097
- Hiroshi Fukuda, Winston Ponder: Australian freshwater assimineids, with a synopsis of the Recent genus-group taxa of the Assimineidae (Mollusca: Caenogastropoda: Rissooidea). Journal of Natural History, 37: 1977-2032, 2003 doi : 10.1080 / 00222930210125380
Individual evidence
- ↑ Micro mollusk breaks record for world's tiniest snail
- ↑ Osborne: Acmella nana: World's tiniest land snails discovered in Borneo measuring just 0.7mm in diameter ( page no longer available , search in web archives ) Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice. on International Business Time from November 2, 2015
- ↑ Douglas Main: Researchers Discover 48 New Snail Species, Including World's Smallest on Newsweek
- ↑ World's Smallest Snail Found: Acmella nana on Sci-News.com from November 3, 2015 ( Memento from November 4, 2015 in the Internet Archive )
- ↑ Rachel Feltman: World's tiniest land snail breaks a record made just weeks ago. Washington Post November 3, 2015
- ↑ Barna Páll-Gergely, András Hunyadi, Adrienne Jokum, Takahiro Asami: Seven new hypselostomatid species from China, including some of the world's smallest land snails (Gastropoda, Pulmonata, Orthurethra). ZooKeys 523: 31-62, 2015. doi : 10.3897 / zookeys.523.6114
- ↑ Researchers discover the smallest snail in the world on Borneo
