Tag: arachnology

Spider eat spider: Scientists discover 18 new spider-hunting pelican spiders in Madagascar

In 1854, a curious-looking spider was found preserved in 50 million-year-old amber. With an elongated neck-like structure and long mouthparts that protruded from the “head” like an angled beak, the arachnid bore a striking resemblance to a tiny pelican. A few decades later when living pelican spiders were discovered in Madagascar, arachnologists learned that their behavior is as unusual as their appearance, but because these spiders live in remote parts of the world they remained largely unstudied–until recently.

At the Smithsonian’s National Museum of Natural History, curator of arachnids and myriapods Hannah Wood has examined and analyzed hundreds of pelican spiders both in the field in Madagascar and through study of pelican spiders preserved in museum collections. Her analysis, focused on spiders of the Eriauchenius and Madagascarchaea genera, sorted the spiders she studied into 26 different species–18 of which have never before been described. Wood and colleague Nikolaj Scharff of the University of Copenhagen describe all 26 pelican spider species in the Jan. 11 issue of the journal Zookeys.

Wood says pelican spiders are well known among arachnologists not only for their unusual appearance, but also for the way they use their long “necks” and jaw-like mouthparts to prey on other spiders. “These spiders attest to the unique biology that diversified in Madagascar,” she said.

Pelican spiders are active hunters, prowling the forest at night and following long silk draglines that lead them to their spider prey. When a pelican spider finds a victim, it swiftly reaches out and impales it on its long, fang-tipped “jaws,” or chelicerae. Then it holds the capture away from its body, keeping itself safe from potential counterattacks, until the victim dies.

Today’s pelican spiders are “living fossils,” Wood says–remarkably similar to species found preserved in the fossil record from as long as 165 million years ago. Because the living spiders were found after their ancestors had been uncovered in the fossil record and presumed extinct, they can be considered a “Lazarus” taxon. In addition to Madagascar, modern-day pelican spiders have been found in South Africa and Australia–a distribution pattern that suggests their ancestors were dispersed to these landmasses when the Earth’s supercontinent Pangaea began to break up around 175 million years ago.

Madagascar is home to vast numbers of plant and animal species that exist only on the island, but until recently, only a few species of pelican spiders had been documented there. In 2000, the California Academy of Sciences launched a massive arthropod inventory in Madagascar, collecting spiders, insects and other invertebrates from all over the island.

Wood used those collections, along with specimens from other museums and spiders that she collected during her own field work in Madagascar, to conduct her study. Her detailed observations and measurements of hundreds of specimens led to the identification of 18 new species–but Wood says there are almost certainly more to be discovered. As field workers continue to collect specimens across Madagascar, “I think there’s going to be a lot more species that haven’t yet been described or documented,” she said.

The spiders Wood personally collected, including holotypes (the exemplar specimens) for several of the new species, will join the U.S. National Entomological Collection at the Smithsonian, the second-largest insect collection in the world, where they will be preserved and accessible for further research by scientists across the globe.

All of the pelican spiders that Wood described live only in Madagascar, an island whose tremendous biodiversity is currently threatened by widespread deforestation. The new species add to scientists’ understanding of that biodiversity, and will help Wood investigate how pelican spiders’ unusual traits have evolved and diversified over time. They also highlight the case for conserving what remains of Madagascar’s forests and the biodiversity they contain, she says.

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Funding for this study was provided by the Danish National Research Foundation and the National Science Foundation.

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Original source:

Wood HM, Scharff N (2018) A review of the Madagascan pelican spiders of the genera Eriauchenius O. Pickard-Cambridge, 1881 and Madagascarchaea gen. n. (Araneae, Archaeidae). ZooKeys 727: 1-96. https://doi.org/10.3897/zookeys.727.20222

New species of marine spider emerges at low tide to remind scientists of Bob Marley

It was 02:00h on 11 January 2009 when the sea along the coastline of Australia’s “Sunshine State” of Queensland receded to such an extent that it exposed a population of water-adapted spiders. The observant researchers who would later describe these spiders as a species new to science, were quick to associate their emergence with reggae legend Bob Marley and his song “High Tide or Low Tide”.

In their paper, published in the open access journal Evolutionary Systematics, the team of Drs. Barbara Baehr, Robert Raven and Danilo Harms, affiliated with Queensland Museum and the University of Hamburg, describe the new Bob Marley’s intertidal spider and also provide new information on two of its previously known, yet understudied, relatives from Samoa and Western Australia.

Unlike the spiders which people are familiar with, the intertidal species, whose representative is Bob Marley’s namesake, are truly marine. They have adapted to the underwater life by hiding in barnacle shells, corals or kelp holdfast during high tide. To breathe, they build air chambers from silk. Once the sea water recedes, though, they are out and about hunting small invertebrates that roam the surfaces of the nearby rocks, corals and plants.

The new species, listed under the scientific name of Desis bobmarleyi, is described based on male and female specimens spotted and collected from brain coral on that night in January.

Both sexes are characterised by predominantly red-brown colours, while their legs are orange-brown and covered with a dense layer of long, thin and dark grey hair-like structures. The females appear to be larger in size with the studied specimen measuring nearly 9 mm, whereas the male was about 6 mm long.

While the exact distribution range of the newly described species remains unknown, it is currently recorded from the intertidal zones of the Great Barrier Reef on the north-eastern coast of Queensland.

“The song ‘High Tide or Low Tide’ promotes love and friendship through all struggles of life,” explain the authors for their curious choice of a name. “It is his music that aided a field trip to Port Douglas in coastal Queensland, Australia, to collect spiders with a highly unique biology.”

Apart from reporting their research, the scientists use their paper to pay tribute to a German naturalist from the late 19th century – Amalie Dietrich, as well as the famous Jamaican singer and songwriter. Both admirable figures, even if representative of very different fields, are seen by the authors as examples of “the adventurous and resilient at heart” human nature in pursuit of freedom and independence.

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Original source:

Baehr BC, Raven R, Harms D (2017) “High Tide or Low Tide”: Desis bobmarleyi sp. n., a new spider from coral reefs in Australia’s Sunshine State and its relative from Sāmoa (Araneae, Desidae, Desis). Evolutionary Systematics 1: 111-120. https://doi.org/10.3897/evolsyst.1.15735

Bird spiders detectives: The solution to a 200-year-old hairy mystery

Three species and three genera of birdeater spiders are described as new to science in a paper recently published in the open access journal ZooKeys. In their study, the Brazilian spider experts, Drs. Caroline Fukushima and Rogério Bertani, Laboratory of Ecology and Evolution, Instituto Butantan, report the diversity of the oldest tarantula genus (Avicularia), whose name derives from a famous 18th-century illustration depicting a bird caught by a spider.

Even though these harmless tarantulas have long been a favourite exotic pet around the world, their identity has remained problematic ever since the first species was described back in 1758 by the “father of modern taxonomy”, Carl Linnaeus.

“He described the species based on a hodgepodge of spiders,” explain the authors. “Over the next centuries, other species with completely different characteristics were called Avicularia creating a huge mess.” As a result, basic questions, such as the characteristic traits of the genus, the number of its species and their localities, have been left unanswered.

To address the confusion, the team studied both newly collected specimens and also specimens from around the world which had previously been deposited in museum collections. Thus, they concluded that, instead of the 49 species previously assigned to the problematic genus, there are in fact only 12, including three new to science.

One of the new species, Avicularia merianae, is named after Maria Sybilla Merian (1647-1717), a pioneering scientist and a remarkable artist who made the famous illustration of a spider eating a bird. In fact, it was her work that gave birth to the popular name used for a whole group of spiders, also known as birdeaters or bird spiders.

Meanwhile, the name of the new genus Ybyrapora, which occurs in the Brazilian Atlantic rainforest, translates to “those that live in trees” from the indigenous local language Tupi. It refers to the arboreal habitat of these species. The other two tarantula genera live exclusively on the Caribbean Islands.

“People think all biologists are like Indiana Jones, with their daily lives full of adventures in the wild. But most of the time, they are much more like Sherlock Holmes – sitting on a chair, collecting and analysing clues (specimens and scientific papers) and then using logical reasoning to solve Nature’s mysteries,” comments Dr. Caroline Fukushima.

“We, taxonomists, are ‘wildlife detectives’ who play an essential role not only in biology and conservation. Our work can also become the grounds for new technologies, medicines and ideas that could solve a variety of problems,” she adds.

“We are delighted to have finally closed one of the oldest unsolved cases,” the authors conclude.

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Original source:

Fukushima CS, Bertani R (2017) Taxonomic revision and cladistic analysis of Avicularia Lamarck, 1818 (Araneae, Theraphosidae, Aviculariinae) with description of three new aviculariine genera. ZooKeys 659: 1-185. https://doi.org/10.3897/zookeys.659.10717

Family of scaffold web spiders increased with ~20% following discovery of 43 new species

Recent study into spider specimens collected from across China, Indonesia, Philippines, Singapore, Thailand, Vietnam and Madagascar over the past 15 years, revealed the striking number of 43 scaffold web spiders that have stayed hidden from science until now. By describing the new species in a paper published in the open access journal ZooKeys, scientists from Sichuan University and the Chinese Academy of Sciences increase the number of a scaffold web spider family (Nesticidae), known from around the world, with about twenty percents.

The studied family of scaffold web spiders is a relatively small group of arachnids, which can be found at almost any locality, apart from Siberia, Central Asia, Northern and Southern Africa and places at high latitude. Prior to the study of Drs Yucheng Lin, Francesco Ballarin and Shuqiang Li, the species counted 245 in total, 12 of which are extinct and known from fossils only. A curious peculiarity in these spiders is their comb of serrated bristles, located on their rear legs, used to pull silk bands for their webs.

Although large-scale taxonomic surveys of scaffold web spiders have long remained scarce, recently the interest towards spider research in China and Southeast Asia has seen a significant rise. Thus, over the last 15 years, Chinese, American and European arachnologists have carried out several surveys, ending up with precious samples. As a result, Dr Yucheng Lin and his team followed with deeper morphological and molecular studies to discover remarkable diversity.

In their work, the researchers have also established a new genus (Speleoticus) for five previously known, but misplaced species, which spend a lot of their time taking shelter in caves.

The majority of scaffold web spiders occur in temperate areas of the Holarctic realm, where the species tend to be medium-sized, long-legged, and prefer cave-like environments. The species found in the tropical and subtropical areas are, on the other hand, usually smaller, with shorter legs, and can be quite often spotted outside, where they crawl in forest litter, on grass, and under stones.

Original source:

Lin Y, Ballarin F, Li S (2016) A survey of the spider family Nesticidae (Arachnida, Araneae) in Asia and Madagascar, with the description of forty-three new species. ZooKeys 627: 1-168. https://doi.org/10.3897/zookeys.627.8629