Subterranean, blind water mite discovered in Vietnamese cave

A water mite with a complete absence of eyes and measuring only 1mm in length has been discovered during an expedition by scientists in a cave on Cat Ba Island, Halong Bay, Vietnam.

The subterranean fauna of southern and southeastern Asia is known to be poorly documented, with accurate information on groundwater fauna in Vietnamese karst landscapes (defined by its composition of soluble bedrock, usually limestone or marble) particularly scarce.

Halong Bay, Vietnam. Credit: Rachel Austin/FFI
Halong Bay, Vietnam. Credit: Rachel Austin/FFI

In an attempt to begin remedying this gap in knowledge, Fauna & Flora International invited Dr Boris Sket and his colleague Dr Peter Trontelj, a speleobiologist (a subterranean and cave fauna biologist), to lead an expedition to study the subterranean fauna of the karst landscapes of northern Vietnam.

Dr Sket explains, “I was incredibly eager to visit Halong Bay, and had wished to do so for many years. Anchihaline (coastal) fauna is one of my favourite research subjects and the landscape here is marvelous. I knew there must be anchihaline caves in the region, waiting to be explored.”

Dr Sket was right. “There is a complex and diverse aquatic community of micro invertebrates inhabiting small fissures and cracks in the gaps between the fossil caves and the surface. These small systems of fissures have traditionally been neglected as the main habitat for water mites, but this is where we found many new species.”

Whilst no photographs currently exist of the Nilotonia Sketi, the above is an example of a similar mite species from Ha Long. Credit: Dr Boris Sket
Whilst no photographs currently exist of the Nilotonia Sketi, the above is an example of a similar mite species from Ha Long. Credit: Dr Boris Sket

As well as the blind water mite, named Nilotonia Sketi after Dr Sket, the biologists found several new troglobiotic (specialised subterranean) animals, while investigating a number of caves throughout the archipelago, most of which were also previously unknown to science.

Dr Sket continues, “Amongst the discoveries were a small troglobiotic fish Draconectes narinosus (new genus, new species) in a small island, where freshwater fish are not expected to be found, as well as a tiny amphipod crustacean Seborgia vietnamica (new species) which we think is most probably the only food resource of the new fish.”

Due to the need for complete scientific accuracy, new species description is a time consuming task, with this one in particular taking close to ten years to be completed.

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