Tiny thorn snail discovered in Panama’s backyard

Close-up view of live individuals of the new species crawling on a leaf.

Discoveries of biodiversity at the Lilliputian scale are more tedious than it is for larger animals like elephants, for example. Furthermore, an analysis producing a DNA barcode – a taxonomic method using a short snippet of an organism’s DNA – is not enough to adequately identify it to the species level.

In the case of tiny thorn snails – appearing as minute white flecks grazing in moist, decomposing leaf litter – it is the shell that provides additional and reliable information needed to verify or question molecular assessment of these otherwise, nondescript critters.

Broadleaf forest litter with white arrows indicating the newly described species on the leaves.

However, at 2 mm, thorn snails are too small and fragile to handle and the few, if any, tangible details on the outside of the shells can only be seen using a high-powered microscope and computed tomographic (CT) images.

This is exactly how the interdisciplinary team of Dr Adrienne Jochum, Naturhistorisches Museum der Burgergemeinde Bern (NMBE) and University of Bern, Dr. Bernhard Ruthensteiner, Zoologische Staatssammlung Muenchen, Germany, Dr. Marian Kampschulte, University Hospital of Giessen and Marburg, Gunhild Martels, Justus-Liebig University Giessen, Jeannette Kneubühler, NMBE and University of Bern, and Dr. Adrien Favre, Senckenberg Research Institute and Natural History Museum Frankfurt, managed to clarify the identity of a new Panamanian species. Their study is published in the open-access journal ZooKeys.

Even though the molecular analysis flagged what it was later to be named as the new to science species, Carychium panamaense, the examination left no shell for the description of the new snail to be completed, let alone to serve as tangible, voucher material in a museum collection available to future researchers. The mini forest compost-grazer had to wait for another five years and Dr. A. Favre, who collected fresh material while traveling in Panama.

The new snail is currently the second member of the family Carychiidae to be discovered in Panama. The first Panamanian, and southern-most member of its kind in the Western Hemisphere, is C. zarzaae, which was also described by Dr. A. Jochum and her team along with two sister species from North and Central America. The study was published in ZooKeys last year.

Much like X-rays showing the degree of damage in a broken bone, CT images visualise the degree of sinuosity of the potato chip-like wedge (lamella) along the spindle-like mast (columella) inside the thorn snail’s shell. These structures provide stability and surface area on which the snail exerts muscular traction while manoeuvring the unwieldy and pointed, signature thorn-like shell into tight nooks and crannies. The alignment and degree of waviness of the lamella on the columella is also used by malacologists (mollusc specialists) to differentiate the species.

These are computed tomographic (CT) images of the new thorn snail species.

Normally, a study of a thorn snail’s shell would require drilling out minute ‘windows’ in the shell by using a fine needle under a high microscope magnification.

“This miserable method requires much patience and dexterity and all too often, the shell springs open into oblivion or disintegrates into dust under pressure,” explains Dr. A. Jochum. “By exposing the delicate lamella using non-manipulative CT imaging, valuable shell material is conserved and unknown diversity in thorn snails becomes widely accessible for further study and subsequent conservation measures.”

The authors are hopeful that C. panamaense and C. zarzaae, which both inhabit the La Amistad International Park, Chiriquí, will remain a conservation priority along with other animalian treasures including the Resplendent Quetzal, Three-Wattled Bellbird and the Crested Eagles.

The park is considered the 1st bi-national biosphere reserve, as it occupies land in both Costa Rica and Panama, and constitutes a UNESCO World Heritage Site since 1990.

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Original Source:

Jochum A, Ruthensteiner B, Kampschulte M, Martels G, Kneubühler J, Favre A (2018) Fulfilling the taxonomic consequence after DNA Barcoding: Carychium panamaense sp. n. (Eupulmonata, Ellobioidea, Carychiidae) from Panama is described using computed tomographic (CT) imaging. ZooKeys 795: 1-12. https://doi.org/10.3897/zookeys.795.29339

New ‘scaly’ snails species group following striking discoveries from Malaysian Borneo

Six new species of unique land snails whose shells are covered with what look like scales have been described from the biodiversity hotspot of Malaysian Borneo by scientists Mohd Zacaery Khalik, Universiti Malaysia Sarawak, Kasper Hendriks, University of Groningen, Jaap Vermeulen, JK Art & Science, and Prof Menno Schilthuizen, Naturalis Biodiversity Center. Their paper is published in the open access journal ZooKeys.

Thanks to their conspicuous structures, the mollusks have been added to a brand new species group of land snails to be commonly known as the ‘scaly’ snails, so that they can be set apart from the rest in the genus Georissa. Why it is that only some of the species in the genus sport the unique ‘scales’, remains unknown.

Fascinated with the minute ‘scaly’ snail fauna of Borneo, the researchers carried out fieldwork between 2015 and 2017 to find out how these curious shells evolved. In addition, they also examined material deposited in museum and private snail collections.

Apart from DNA data, which is nowadays commonly used in species identification, the team turned to yet-to-become-popular modern tools such as 3D modelling, conducted through X-ray scanning. By doing so, the researchers managed to look at both the inner and outer surfaces of the shells of the tiny specimens from every angle and position, and examine them in great detail.

The researchers note that to identify the ‘scaly’ snails to species level, one needs a combination of both DNA and morphological data:

“Objective species delimitation based solely on molecular data will not be successful for the ‘scaly’ snails in Georissa, at least if one wishes for the taxonomy to reflect morphology as well.”

The six new species are all named after the localities they have been originally collected from, in order to create awareness for species and habitat conservation.

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Watch rotation and cross-section of the 3D models of the studied species here.

Original source:

Khalik MZ, Hendriks K, Vermeulen JJ, Schilthuizen M (2018) A molecular and conchological dissection of the “scaly” Georissa of Malaysian Borneo (Gastropoda, Neritimorpha, Hydrocenidae). ZooKeys 773: 1-55. https://doi.org/10.3897/zookeys.773.24878