Citizen scientists discover a new species of ‘snug’ deep in a forest in Brunei

Somewhere between a slug and a snail, semi-slugs – also known as ‘snugs’ – have a shell that’s too small for them to retract into, but still acts as a kind protective backpack.

On the island of Borneo there are about 10 species of semi-slugs, genus Microparmarion. Now, according to a new study in the Biodiversity Data Journal, citizen scientists have discovered another one.

“During three citizen-science expeditions/field courses in the lowland forests of Ulu Temburong National Park, Brunei Darussalam, in the northwest of the island of Borneo, we found several individuals of a Microparmarion species,” the authors write in the paper.

“This new species stands out because of its shell, which, unlike other north Bornean species of the genus, has no discernible whorls.”

Inside a tropical rainforest
The locality where Microparmarion sallehi was found. Credit: Pierre Escoubas

A citizen scientist made the initial discovery during the first biodiversity discovery trip in 2018. The expeditions are organised in collaboration between scientific travel agency Taxon Expeditions and Universiti Brunei Darussalam (UBD).

Most participants and the resident “snail expert” passed by the new species without a second glance, but UK citizen scientist Simon Berenyi spotted the snug on a dead leaf suspended over the trail they were walking along. Since most of Borneo’s semi-slug species are found in the cooler forests of the mountains, to find this snug in the hot lowland forest was a surprise.

Two images of a semi-slug from the side
Microparmarion salleh; a right lateral view; b left lateral view. Credit: DOI:10.3897/BDJ.11.e101579

Over the years, successive expeditions to the same area uncovered more specimens and in total five individuals were studied. Most recently in 2022, a team consisting of UBD students Nurilya Ezzwan and Izzah Hamdani and US citizen scientist Harrison Wu, finished the description – studying the animals’ shell, reproductive organs, and DNA for publication.

“Although the species externally resembled other Bornean lowland congenerics, DNA-barcoding performed in the field lab showed that the Brunei specimens belong to a distantly related species. Further morphological examination in the field lab confirmed this,” they wrote.

A team of citizen scientists in the brunei forest, searching for slugs and snails
A team of citizen scientists in the Brunei forest, searching for slugs and snails. Credit: Pierre Escoubas

On the last night of the 2022 expedition the team voted on the scientific name for the new species, settling on Microparmarion salleh after the supervisor of the Kuala Belalong Field Studies Centre, Md Salleh Abdullah Bat, who retired shortly after.

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