Field work and the thrill of discovery

MSU's blog | Created 4 months ago

Working at a museum involves a lot of time indoors. We spend hours looking down microscopes, reading papers, looking at DNA sequence data and databasing the collections. However, when we do get outside we get to visit some incredibly diverse and striking landscapes, seeking new species from every corner of the State. For many of us, this is why we study biodiversity: we feel drawn to these unexplored places and seek to discover species that have never been seen before.

In March 2015, the Western Australian Museum led a field trip to the Pilbara, visiting Karijini and Millstream-Chichester national parks. Led by myself (Joel Huey), and funded through the Gorgon Barrow Island Net Conservation Benefits Fund (NCB, http://gorgon-ncb.org.au/), the trip targeted arachnids, insects, reptiles, mammals, and land snails. Extensive collections do exist at the WA Museum from these parks, however, the Pilbara Conservation Systematics project is primarily interested in collecting exemplars that can be sequenced for DNA. Unfortunately, many specimens in the WA Museum Collection from these parks were collected in pitfall traps that do not preserve DNA well.

The trip had many highlights, including some spectacular scenery. But the real thrill in any biological expedition is finding an organism that you know is new to science.

Before embarking on a productive few days exploring the landscape around Mulla Mulla camp at Millstream-Chichester National Park, the Yindjibarndi Elders provided a Welcome to Country and introduced us to the Aboriginal rangers who assisted us in our fieldwork. WA Museum Senior Curator for Arachnology Dr Mark Harvey was particularly interested in a unique habitat type: in the arid zone regions of the southern hemisphere, the southern faces of cliff and gorge walls provide an environmentally stable habitat for animals. This is because the sun passes to the north of the geological feature, leaving the rocks and shrubs at the base of the cliff in permanent shade. For organisms that cannot tolerate the extreme heat and desiccation of the surrounding desert, these habitats are vital for long-term survival. These habitats are difficult to access and are discontinuously spread throughout the landscape. As such, they often act as refugia for species that may have been in isolation for millions of years, driving speciation and preserving taxa that are more commonly found in wetter habitats.

After examining topographic maps and chatting to the resident (and extremely helpful) Department of Parks and Wildlife staff, we decided to venture forth to George Creek in the north of the park, east of Python Pool. The site is nestled in among the distinctive Chichester Ranges with ancient, eroded hills surrounded by extensive shale slopes. These shale slopes are excellent habitat for small arachnids because individuals can move deeper into the slope when conditions become unfavourable on the surface. The eight WA Museum researchers carefully overturned rocks and boulders on the slope on the south side of the hill seeking a particular order of arachnid, pseudoscorpions.

 

Shale slope at George Creek, Millstream Chichester National Park

Shale slope at George River, Millstream Chichester National Park (Image copyright: Mark Harvey / WA Museum)

Pseudoscorpions, like scorpions, have two pincers they use to grasp food and sense their surroundings. However, unlike scorpions, pseudoscorpions lack the stinging tail and are significantly smaller, with the largest species only reaching 12 millimetres long. Pseudoscorpions are usually found in leaf litter, under rocks or tree bark, or in caves. They have even been found in library books, which has led to them sometimes being called ‘book scorpions’.

It didn’t take long to have some success at George Creek. A few hours of searching revealed possibly 10 new species, from seven genera and five families. The slope was teeming with pseudoscorpion diversity! But the excitement was reserved for one particular find; Linette Umbrello, a PhD candidate from the University of Western Australia and WA Museum Zoology Research Associate who’s studying small carnivorous mammals in collaboration with the WA Museum, stumbled across an odd looking pseudoscorpion, which immediately piqued Mark Harvey’s interest. The juvenile specimen belonged to an extremely rare genus, Feaella, which had only been observed from four other sites in the Pilbara. Interestingly, those other sites were very similar to George Creek: large rocky slopes with plenty of shelter, deep among the rocks.

While the find of this new species was certainly exciting, being almost 200 kilometres from the closest known population of Feaella, it was a bittersweet find. Juvenile pseudoscorpions often lack the morphological features required to make a positive identification or to describe a new species. While DNA sequencing could confirm or deny the discovery, an adult specimen would provide both DNA and morphology. Of course, by this point it was getting hot in the March sun and we were all looking forward to returning to the cool shade of Mulla Mulla Camp, but science doesn’t rest. So we pushed on seeking that needle in a haystack. Unfortunately, after hours of searching, another Feaella could not be found and with a long, bumpy ride back to camp ahead of us, we had to concede defeat.

Two days later, Mark Harvey and myself decided to have one last crack at finding an adult specimen and returned to George Creek. We started out in a pretty buoyant mood, but after two hours on the red rocks, and the mercury rising, the conversation dwindled to a few monosyllabic words, and the sound of swatting flies and rolling rocks. Possibly 30 minutes before we would have to call off the search, and beyond the point where I had gone cross-eyed looking at tiny invertebrates scuttling across overturned rocks, Mark let out an exultant yell. He crawled out of a four-foot-deep hole he had cleared underneath two huge boulders, holding aloft the prize: an adult male Feaella.

 

Feaella linetteae

Feaella linetteae (Image copyright: Mark Harvey / WA Museum)

Morphological and genetic analyses supported our hypothesis that the Feaella specimens did belong to a new species. Along with two other new species of Feaella, the George Creek specimens were described in a recent publication in Invertebrate Systematics. Feaella linetteae now bears the name of its discoverer, Linette Umbrello. For me, this is one of the truly rewarding parts of studying Australia’s biodiversity. New discoveries lay hidden around every corner, and indeed, under every rock. All you have to do is take the time to roll them over.