New tarantula species from Angola distinct with a one-of-a-kind ‘horn’ on its back

A new to science species of tarantula with a peculiar horn-like protuberance sticking out of its back was recently identified from Angola, a largely underexplored country located at the intersection of several Afrotropical ecoregions.

Collected as part of the National Geographic Okavango Wilderness Project, which aims to uncover the undersampled biodiversity in the entire Okavango catchment of Angola, Namibia and Botswana, thereby paving the way for sustainable conservation in the area, the new arachnid is described in a paper published in the open-access journal African Invertebrates by the team of Drs John Midgley and Ian Engelbrecht.

Although the new spider (Ceratogyrus attonitifer sp.n.) belongs to a group known as horned baboon spiders, the peculiar protuberance is not present in all of these species. Moreover, in the other species – where it is – the structure is completely sclerotised, whereas the Angolan specimens demonstrate a soft and characteristically longer ‘horn’. The function of the curious structure remains unknown.

The new tarantula’s extraordinary morphology has also prompted its species name: C. attonitifer, which is derived from the Latin root attonit– (“astonishment” or “fascination”), and the suffix –fer (“bearer of” or “carrier”). It refers to the astonishment of the authors upon the discovery of the remarkable species.

“No other spider in the world possesses a similar foveal protuberance,” comment the authors of the paper.

Individual of the newly described species in defensive posture in its natural habitat. Photo by Kostadine Luchansky.

During a series of surveys between 2015 and 2016, the researchers collected several female specimens from the miombo forests of central Angola. To find them, the team would normally spend the day locating burrows, often hidden among grass tufts, but sometimes found in open sand, and excavate specimens during the night. Interestingly, whenever the researchers placed an object in the burrow, the spiders were quick and eager to attack it.

The indigenous people in the region provided additional information about the biology and lifestyle of the baboon spider. While undescribed and unknown to the experts until very recently, the arachnid has long been going by the name “chandachuly” among the local tribes. Thanks to their reports, information about the animal’s behaviour could also be noted. The tarantula tends to prey on insects and the females can be seen enlarging already existing burrows rather than digging their own. Also, the venom of the newly described species is said to not be dangerous to humans, even though there have been some fatalities caused by infected bites gone untreated due to poor medical access.

In conclusion, the researchers note that the discovery of the novel baboon spider from Angola does not only extend substantially the known distributional range of the genus, but can also serve as further evidence of the hugely unreported endemic fauna of the country:

“The general paucity of biodiversity data for Angola is clearly illustrated by this example with theraphosid spiders, highlighting the importance of collecting specimens in biodiversity frontiers.”

Apart from the described species, the survey produced specimens of two other potentially new to science species and range expansions for other genera. However, the available material is so far insufficient to formally diagnose and describe them.

The newly described baboon spider species (Ceratogyrus attonitifer), showing the peculiar soft and elongated horn-like protuberance sticking out of its back. Photo by Dr Ian Enelbrecht.

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Original source:

Midgley JM, Engelbrecht I (2019) New collection records for Theraphosidae (Araneae, Mygalomorphae) in Angola, with the description of a remarkable new species of Ceratogyrus. African Invertebrates 60(1): 1-13. https://doi.org/10.3897/afrinvertebr.60.32141

Out of the darkness: A new spider found deep within an Indiana cave

Lead author Marc Milne in the Stygian River Cave and a male specimen of the newly described Islandiana lewisi 

Spiders are ubiquitous within our forests, fields, and backyards. Although you may be used to seeing the beautiful yellow and black spiders of the genus Argiope in your garden, large ground-scurrying wolf spiders in your yard, or spindly cellar spiders in your basement, this new sheet-web-building spider is probably one you haven’t seen before. The reason is that it’s known from a single cave in the world, Stygeon River Cave, in southern Indiana.

The University of Indianapolis assistant professor, Dr. Marc Milne, described the rare species in the open access journal Subterranean Biology with the help of a University of Indianapolis alumnus, Elizabeth Wells, who illustrated the spider for the manuscript.

Sheet weavers, also known as dwarf spiders or money spiders, are minute creatures growing no larger than a few centimetres in length, which makes them particularly elusive. Their peculiar webs are flat and sheet-like, hence their common English name.

Female of the new species Islandiana lewisi

The new spider, Islandiana lewisi, is an homage. Milne was shown the spider by a fellow scientist, Dr. Julian Lewis, who noticed the critter on one of his many cave expeditions. In appreciation for his help, Milne and Wells named the spider after Lewis.

This is the fifteenth species in its genus (Islandiana) and the fifth known to live exclusively in caves. It has been over 30 years since the last species has been added to this group.

At about 2 mm in size, Islandiana lewisi is thought to feed on even smaller arthropods, such as springtails living in the debris on the cave floor. It is unknown when it reproduces or if it exists anywhere else. The spider is likely harmless to humans.

The collectors of the spider, Milne and Lewis, described the hostile conditions within the cave, which the new species calls home: “because the cave floods from time to time, the insides were wet, muddy, slippery, and dangerous to walk on without the proper equipment.”

Milne and Lewis found the spider in small, horizontal webs between large, mud-caked boulders in the largest room in the cave. It was collected in October 2016 with the permission of the landowner.

Milne hypothesized that he had collected something special, stating, “I didn’t know what the spider was at first, I just thought it was odd that so many were living within this dark cave with no other spider species around.”

After returning to the lab and inspecting the spider under a microscope, Milne initially misidentified the species. However, when he re-examined it months later, he realized that the species was indeed new to science.

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Original source:

Milne MA, Wells E (2018) A new species of spider (Araneae, Linyphiidae, Islandiana) from a southern Indiana cave. Subterranean Biology 26: 19-26. https://doi.org/10.3897/subtbiol.26.25605