Not quite an ant…

The discovery of the antlike jumping spiders of Sri Lanka:

Sri Lanka is one of the smallest, but biologically one of the most diverse countries in Asia. So it is recognized as a biodiversity hotspot of global and national importance. The country’s varied climate and diverse geographical conditions have given rise to this rich species diversity, believed to be the highest in Asia in terms of unit land area. The diversity of ecosystems in the country has resulted in a host of habitats, which contain high genetic diversity.

Spiders (order Araneae) are arthropods that have eight legs and chelicerae with fangs that inject venom. They are highly diverse group of invertebrates and occupy various habitats. Professor Suresh P. Benjamin, Associate Research Professor of the Department of Ecology and Environmental Biology, National Institute of Fundamental Studies, Kandy, has been able to describe/redescribe all nominal species of ant-mimicking jumping spiders of the genus Myrmarachne in Sri Lanka, based on type and newly collected material. Also he has been able to skillfully identify and describe three new ant-mimicking jumping spiders’ species. His discoveries were published in the May issue of international peer reviewed Journal of Natural History.

Jumping spider

The ant-mimicking genus Myrmarachne is one of the most species rich genera of Salticidae (jumping spider). The Myrmarachne is a genus of jumping spiders which imitate the ant by waving their front legs in the air to simulate the antennae. Some species also look strikingly like ants.

Apart from a few studies, generally very little is known of the behaviour and life history of the Myrmarachne. Although they generally tend to be found close to ants, they are known to actively avoid contact with them.

However, after the work of Professor P. Benjamin, a total of 12 valid species are now well known from the island and six of them are endemic to Sri Lanka Myrmarachneaurantiaca, Myrmarachnedishani and Myrmarachnemorningside are the newly described ant-like jumping spiders species identified by Professor Benjamin. All species are well illustrated facilitating easy identification in the field.

Myrmarachneaurantiaca, one of the three new species was discovered from the Ethagala range of Kurunegala District, North Western Province.

M.aurantiaca is separated from other Sri Lankan Myrmarachne species by the body size, dorsally flat surface of the male chelicerae and reddish orange-coloured carapace

Myrmarachnedishani, the second new species was discovered from Eastern Sinharaja forest. The species has been named for his wife Dishani P. Benjamin. It can be clearly identified from all other Sri Lankan species of the genus, except for M. imbellis, by the presence of a cylindrical opisthosoma, which lacks any visible, constrict.

Morningside

The Holotypeof Myrmarachne morningside, the third new species was discovered from Eastern Sinharaja forest, Morningside section. M. morningside is very similar in outward appearance to M. spissa. Separated from it by the disk-shapedtegulum and shiny appearance, mostly of the dorsal parts of the prosoma. It is endemic to Sri Lanka. This spices was found to be present in Gilimale Forest as well.

Apart from these three newly discovered species, Professor Benjamin has also been able to re-describe several more Myrmarachne species, which were previously known, by using newly collected specimens. Those species are Myrmarachneimbellis, Myrmarachnepaludosa ,Myrmarachnepaludos,Myrmarachneprava., Myrmarachneplataleoides and Myrmarachnespissa. Among those, Myrmarachnepaludosa is found only in Sri Lanka and is probably endemic, as it occurs only in primary forest of the wet zone and is absent in the surrounding dry forest and coastal regions.

The antlike jumping spiders are a less known bio diversity feature in Sri Lanka. This study opens yet another window to Sri Lanka’s rich but threatened bio diversity. The study was funded by the Institute of Fundamental Studies with additional funding coming from a fellowship from the Alexander von Humboldt Foundation.

Professor Suresh P. Benjamin was interviewed in this article compiled by Pradeep Piyathilaka,Communication & Media Officer, Science Education & Dissemination Unit, National Institute of Fundamental Studies, Kandy