Researchers Discover World’s Tiniest Land Snail in Northeastern Borneo

Summary: Researchers discovered the world's tiniest land snail in the Malaysian state of Sabah, northeastern Borneo, according to a study in Nov. 2's ZooKeys.

World’s tiniest land snail, Acmella nana, bejewels the ZooKeys paper describing it; illustration of A. nana by Jaap J. Vermeulen; photo by Prof. Dr. Menno Schilthuizen, Naturalis Biodiversity Center: CC BY 4.0 International, via EurekAlert!

Three researchers announced the discovery in the Malaysian state of Sabah, northeastern Borneo, of 48 new land snail species, including the world’s tiniest, through a study published Nov. 2, 2015, in ZooKeys.

Acmella nana’s shell height of 0.60 to 0.79 millimeters (0.0236 to 0.0311 inches) and width of 0.50 to 0.60 millimeters (0.0197 to 0.0236 inches) beat Angustopila dominikae, whose measurements of 0.86 millimeters (0.0338 inches) by 0.8 millimeters (0.0315 inches) were announced Sept. 28, 2015, in ZooKeys by Barna Páll-Gergely, András Hunyadi, Adrienne Jochum and Takahiro Asami.

The previous record-holder can be found on cliff bases of southern Jiaole Cun in Guanxi, south central China.

The November-published study differentiates 31 known land snail species and 48 new species by shell aperture, dimensions, sculpture and umbilicus (cone-shaped hollow space around which the inner surface coils). The descriptions of Acmella nana and the other 78 species emerge from examination of almost 8,000 lots in Sabah land snail holdings gathered by the study’s three researchers since 1986 for the Institute for Tropical Biology and Conservation collection in Sabah and for the Naturalis Biodiversity Center and Vermeulen collections in Leiden, Netherlands.

The collections furnish only dry specimens minus soft body parts. The study’s three co-authors guess that the little lid-like operculum on Acmella nana’s shell implies water-breathing capabilities of gills and water-rich rock wall-dwelling in caves.

The shiny, translucent whiteness of the world’s tiniest land snail hints at its shell’s main component. Calcium carbonate also is the reason why cement manufacturers quarry limestone.

As article lead author, Institute for Tropical Biology and Conservation research associate, Leiden University professor and Naturalis Biodiversity research scientist, Menno Schilthuizen judges quarrying the major threat to land snail sustainability. Land snails such as Acmella nana keep ecosystems balanced by feeding on bacterial and fungal films on cave walls and on dead and decaying matter in limestone hills.

Dr. Schilthuizen also links die-offs with environmental stress and natural catastrophes since “A blazing forest fire at Loloposon Cave [on Mount Trusmadi] could wipe out the entire population of Diplommatina tylocheilos.”

Twenty-five-year collaborations mean exciting announcements, such as 10 jewel-like micro-landsnail species in ZooKeys on March 25, 2014. Dr. Schilthuizen notes: “When we go to a limestone hill, we just bring some strong plastic bags, and we collect a lot of soil and litter and dirt from underneath the limestone cliffs. We stir it around a lot so that the sand and clay sinks to the bottom, but the shells -- which contain a bubble of air -- float. You can sometimes get thousands or tens of thousands of shells from a few liters of soil, including these very tiny ones.”

The trio now offers the world’s tiniest snail and its strangest, Ditropopsis davisoni, whose detached whorl curlicues its shell.

Ditropopsis davisoni rates as the world's strangest snail, with its detached whorl curlicuing its shell; Figures 9, A-B, Ditropopsis davisoni sp. n.; Figures 10, A-C, Ditropopsis trachychilus sp. n.; Figures 11, A-D, Ditropopsis koperbergi; J.J. Vermeulen et al., "Additions to the knowledge of the land snails of Sabah (Malaysia, Borneo), including 48 new species," ZooKeys, vol. 531, Figure 9-11: CC BY 4.0 International, via ZooKeys

Acknowledgment

My special thanks to talented artists and photographers/concerned organizations who make their fine images available on the internet.

Image credits:

World’s tiniest land snail, Acmella nana, bejewels the ZooKeys paper describing it; illustration of A. nana by Jaap J. Vermeulen; photo by Prof. Dr. Menno Schilthuizen, Naturalis Biodiversity Center: CC BY 4.0 International, via EurekAlert! @ https://www.eurekalert.org/multimedia/616422; (EurekAlert! news release URL @ https://www.eurekalert.org/news-releases/622036); (former URL @ http://www.eurekalert.org/multimedia/pub/102144.php?from=310218)

Ditropopsis davisoni rates as the world's strangest snail, with its detached whorl curlicuing its shell; Figures 9, A-B, Ditropopsis davisoni sp. n.; Figures 10, A-C, Ditropopsis trachychilus sp. n.; Figures 11, A-D, Ditropopsis koperbergi; J.J. Vermeulen et al., "Additions to the knowledge of the land snails of Sabah (Malaysia, Borneo), including 48 new species," ZooKeys, vol. 531, Figure 9-11: CC BY 4.0 International, via ZooKeys @ ; (article URL @ http://zookeys.pensoft.net/articles.php?id=6097)

For further information:

GeoBeats News. 3 November 2015. "World's Smallest Land Snail And 47 Other New Species Discovered." YouTube.
Available @ https://www.youtube.com/watch?v=_nqoO6lYveo

Liew, Thor-Seng, et al. 25 March 2014. "A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina." ZooKeys 393: 1-107. DOI: 10.3897/zookeys.393.6717
Available @ http://zookeys.pensoft.net/articles.php?id=3659

Main, Douglas. 2 November 2015. "Researchers Discover 48 New Snail Species, Including World's Smallest." Newsweek > Tech & Science.
Available @ http://www.newsweek.com/researchers-discover-worlds-small-snail-again-389875

Páll-Gergely, Barna, et al. 28 September 2015. "Seven new hypselostomatid species from China, including some of the world's smallest land snails." ZooKeys 523: 31-62. DOI: 10.3897/zookeys.523.6114
Available @ http://zookeys.pensoft.net/articles.php?id=6114

Pensoft Publishers. 2 November 2015. "World's tiniest snail record broken with a myriad of new species from Borneo." EurekAlert! > Public Releases.
Available @ http://www.eurekalert.org/pub_releases/2015-11/pp-wts102815.php

Vermeulen, Jaap J. 2 November 2015. "Additions to the knowledge of the land snails of Sabah (Malaysia, Borneo), including 48 new species." ZooKeys 531: 1-139. DOI: 10.3897/zookeys.531.6097
Available @ http://zookeys.pensoft.net/articles.php?id=6097

Zookeys @ZooKeys_Journal. 3 November 2015. "World's tiniest land #snail breaks a record made just weeks ago #Gastropoda." Twitter.
Available @ https://twitter.com/ZooKeys_Journal/status/661555864038457344

ZooKeys @ZooKeys_Journal. 4 November 2015. "Watch our new tiny record-holder, the tiniest A. nana land #snail @museumnaturalis @UMS_EcoCampus @schilthuizen." Twitter.
Available @ https://twitter.com/ZooKeys_Journal/status/661824651954360321