Collecting Australia’s smallest snails: a punctid dot-to-dot across southern Australia

How do you look for one of Australia’s underdog species? The Punctidae, or dot snails, are arguably Australia’s least known land snail group and are often overlooked. Dr Isabel Hyman from the Australian Museum tells us about this search, which has spanned 40 days and 13,500 km of driving all around Australia.

Australia has a large suite of endemic species, but most of the names that we can rattle off easily belong to big, cute, furry or feathery species. While I can’t deny their beauty, for my latest taxonomic project I decided to go for the underdog – arguably Australia’s least-known, most overlooked land snail group, the Punctidae or dot snails.

Invertebrate species make up most of the world’s diversity, but receive a disproportionally small amount of attention. And the smaller they are, the less attention they seem to receive! The dot snails have around 35 described species in mainland Australia, with additional radiations on Lord Howe Island and Norfolk Island that are not part of this project. They take their name from their tiny size, with most species in the 1-2.5 mm size range, with really big species reaching a whopping 4-5 mm in shell width! Such small snails require specialised collecting techniques, namely the collection and sieving of leaf litter, then searching through the fine debris under a microscope. This tends to make for very long days, collecting in the daylight hours and then sorting long into the night – but is often the only way to get live specimens.

To get this project off the ground, I would need to start with fieldwork across the south of Australia. So I undertook three main collecting trips, one to Tasmania, a second to Victoria and South Australia, and a third covering the Nullarbor plain and Western Australia (plus a few smaller trips to fill collecting gaps). Each of these trips was so fascinating and took me into such beautiful places that I wanted to share some stories and photos from my punctid dot-to-dot around Australia.

First cab off the rank was Tasmania in April 2023. I was joined by Kevin Bonham and Bruno Bell from Hobart, so I set off from Sydney with two very huge suitcases full of collecting gear, including three microscopes! I was completely blown away by the sheer diversity of punctid species in Tasmania, many of them undescribed. We drove across the northern coastline of Tasmania, then down through the Central Plateau and on to Hobart and surrounds. We visited a lot of (very cold) high peaks to find alpine endemics, but also spent time in coastal scrub and lush rainforest. There were some funny moments – including setting up our microscopes and sorting leaf litter at the King Island airport when our flight was delayed, and squeezing five microscopes (and leaf litter sorters) into my single hotel room in Hobart, thanks to additional helpers Otto Bell and Abby Throssell. The trip was a great way to get to know my Tasmanian colleagues and we were extremely successful in our collecting efforts.

In May 2023, Frank Köhler and I set off in an AM vehicle to drive approximately 6,000 km to the Gawler Ranges in South Australia and back, sampling all the way. Once again we experienced a wide variety of habitat types, encompassing the moist forests of Victoria’s Otway Ranges, sand dunes in eastern South Australia, and the arid Gawler Ranges with enormous granite inselbergs, and everything in between, finding many tiny snails along the way.

Finally, in May 2024 Frank and I set off for the Nullarbor and Western Australia. The Nullarbor Plain may not seem like a very fruitful place for snail collecting, but it is honeycombed with limestone caves, and snails often have a strong association with limestone. We searched in and around 20 caves and sinkholes across the Nullarbor and found live snails at every site, including some potentially undescribed species. We were also struck by the stark beauty of the Nullarbor – it’s a stunning place and well worth exploring. We’d like to thank Steve Milner and Barry Coleman for their assistance on this part of the trip.

The second part of our trip was a 3,000 km loop in southwestern Western Australia – south from Perth and then along the south coast to Esperance, north to Coolgardie then back to Perth, collecting all the way. We found plenty of dot snails in coastal vegetation and leaf litter on dunes, but once we got into the drier inland areas, it became a bit tougher – partly because the dot snails in these areas are extremely small (adult size 1.2 to 1.8 mm – imagine how small the babies are) and cannot easily be found by eye. At these sites, we relied on collecting leaf litter from the Mallee scrub and spending hours in the evening sorting it under a microscope. It paid off – amazingly, even at the driest and least promising sites, these tiny snails are usually surviving in small pockets of leaf litter.

All in all, these trips amounted to around 40 days, 13,500 km of driving, hundreds of snails collected, and an estimated 150+ person-hours sorting leaf litter!

So what’s next? The work didn’t end there – since the trips I’ve been very busy working on morphological and molecular studies, including shell measurements, scanning electron microscopy of shells, anatomical studies (which are very challenging with such small snails!), and DNA extraction and sequencing. The first revisions are nearly complete, and I look forward to sharing my findings in future blogs.

Dr Isabel Hyman

Research Scientist, Malacology, AMRI