An arachnologist from the Senckenberg Research Institute in Frankfurt, Germany, has discovered the world’s first eyeless huntsman spider.

The new species, named Sinopoda scurion, is described in a paper in the journal Zootaxa. With a leg span of only 6 cm and a body size of around 12 mm, the spider is certainly not one of the largest representatives of the huntsman spiders, which include more than 1100 species. However, it is the first of its kind in the world without eyes.

“I found the spider in a cave in Laos, around 100 km away from the famous Xe Bang Fai cave,” said Dr Peter Jäger, head of the arachnology section at the Senckenberg Research Institute in Frankfurt. “We already knew of spiders of this genus from other caves, but they always had eyes and complete pigmentation. S. scurion is the first huntsman spider without eyes.”

The regression of the eyes is attributable to living permanently without daylight. This adaptation was also observed in other cave-dwelling spider species by the arachnologist.

“The Sinopoda species described demonstrate all kinds of transitions to cave adaptation – from eight functioning eyes to forms with six, four and two lenses, right up to blind spiders,” Dr Jäger said.

In total, the Frankfurt spider researcher has described nine new species of the genus Sinopoda: S. steineri, S. tham, S. sitkao, S. taa, S. suang, S. peet, S. guap, S. soong and eyeless S. scurion.

The fact that all of the species have been found in caves confirms the animals’ preference for underground habitats.

Because of the small-scale area in which the spider species can be found it is possible to study their adjustment to the cave as a dwelling – the number of eyes present and the visual faculty may possibly shed light on the time of settlement.

“Furthermore, the spiders can be used as indicators for the threat to their habitats. These are often endangered by tourism or the exploitation of the limestone rocks to make cement,” Dr Jäger concluded.

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Bibliographic information: Jager P. 2012. Revision of the genus Sinopoda Jäger 1999 in Laos with discovery of the first eyeless huntsman spider species (Sparassidae: Heteropodinae). Zootaxa 3415: 37–57