Cahyo Rahmadi, from the Indonesian Institute of Sciences (LIPI), and Jeremy Miller, from the Naturalis Museum in Leiden, the Netherlands, named the new species Amauropelma matakecil, in reference to its vestigial eyes that are smaller than those of non-cave-dwelling spiders.
“The eyes on this specimen are so small that they just appear as transparent dots on its head,” Cahyo told Antara in an e-mail.
He added the spider was known to inhabit just three caves in the karst, or limestone, Menoreh Hills area of Purworejo, on the border between Central Java and Yogyakarta.
Cahyo and Miller figure that the new species “appears to fit best in the genus Amauropelma,” based on shared characteristics such as the eye arrangement, the leg spination pattern, the presence of superior tarsal claws and the lack inferior tarsal claws.
However, they also noted that A. matakecil “exhibits characteristics that are not typical of Amauropelma,” including hard rather than soft teeth and differently placed copulatory openings.
They also acknowledged that the new species has eyes, while the only other troglodytic, or cave-dwelling, Amauropelma species, A. undara, does not.
A. undara, like all known species in the genus Amauropelma, is currently only found in the Australian state of Queensland.
“We believe the specimen is a new member of the genus Amauropelma,” Cahyo said.
Cahyo, a recent graduate from Japan’s Graduate School of Science and Engineering at Ibaraki University, said it was hard to find enough specimens in the field.
“They’re very hard to come by and widely spread out,” he said of the arachnid that was first discovered in the Menoreh Hills caves in 2008.
He added the specimens studied for the paper were all female, with the scientists unable to find any male spiders. Male spiders would hopefully help put to rest the question of whether the species really belongs to the genus Amauropelma or to another genus, Janusia, which has also only been confirmed in Australia.
Cahyo said the failure to find any males could also point to the possibility that the spider reproduced asexually.
The more likely explanation, he said, is that the males are simply far more scarce and smaller, hence more difficult to find.
“Keep in mind that spiders have a very extreme sexual dimorphism, where the male is typically much smaller than the female,” he said.
The scientists predicted that if a male specimen was discovered, it would exhibit characteristics similar to those of other male Amauropelma spiders.
“If these predictions are not borne out with the eventual discovery of the male, the generic position of this species may have to be reconsidered,” they wrote.
They also highlighted the potential conservation importance of the new species, given its small population and threats to its limestone cave habitat. “Karst formations in Java are threatened by human activities such as limestone mining and habitat conversion,” they noted.
Source: The Jakarta Globe