Two new species of freshwater mussels discovered in Borneo
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A collaborative research project involving members of the Borneo Studies Network (BSN) has discovered a new genus and two new species of freshwater mussels in Borneo.

BSN is a Borneo-based framework of research and studies network, in which Universiti Brunei Darussalam (UBD) is the current BSN Secretariat. The network aims to facilitate collaboration among higher education institutions and research centres in Borneo across many disciplines including Borneo biodiversity. A number of scientists from four of the 12 founding members of BSN, i.e. UBD, Universiti Malaysia Sabah, Universiti Malaysia Sarawak and Universitas Tanjugpura, were involved in this exciting discovery.

The collaborative research project was led by Dr Alexander Zieritz from the University of Nottingham, who is a well-known expert in freshwater mussels. Other research collaborators who participated in this study were: Dr Leonardo Jainih and Dr Arman Hadi Fikri of Universiti Malaysia Sabah; Dr John Pfeiffer of National Museum of National History; Dr Khairul Adha Rahim of Universiti Malaysia Sarawak; Dr Hari Prayogo, Dr Muhammad Sofwan Anwari and Dr Farah Diba of Universitas Tanjungpura, Dr Hussein Taha of Universiti Brunei Darussalam, Professor Dr Hjh Zohrah Haji Sulaiman of Universiti Teknologi Brunei, Dr Elsa Froufe of CIMAR/CIIMAR-UP Centre of Marine and Environmental Research, AEE; and Dr Manuel Lopes-Lima of CIBIO/InBIO- Research Centre in Biodiversity and Genetic Resources of University of Porto.

The authors noted the declines of existing populations of freshwater mussels on Borneo. This research project involved a number of field surveys carried out in various parts of Brunei Darussalam, Kalimantan, Sabah and Sarawak. However, it was the field surveys carried out in the small streams in Gomantong, Sabah and near Kuala Mendalam, Sarawak that led to the discovery of two new species.The two new species are named Khairuloconcha lunbawangorum and Khairuloconcha sahanae. The former is named after the Lun Bawang tribe of Borneo, whereas the latter is named in honour of the late Dr Sahana Harun, a dedicated freshwater ecologist. These two species belong to a new genus of freshwater mussels, Khairuloconcha, which is named after Dr Khairul Adha A Rahim, one of Borneo's leading aquatic biologists. Through DNA analysis, the two species are found to be closely related to Ctenodesma borneensis.

Borneo exhibits an exceptionally high number of endemic freshwater mussels, meaning the species can only be found in this island and not anywhere else. With the addition of these two species, Borneo now has 15 endemic species out of the 20 species that have been recorded in Borneo, all of which belong to the family Unionidae. The study provides further evidence of the significance of Borneo as a hotspot for freshwater biodiversity.

In addition, the study also recorded Schepmania species, in which its population appears to be declining within the past few decades. Many other species of freshwater mussels in Borneo are also thought to be declining and, in some cases, may already be eradicated. This is likely due to ongoing large scale deforestation in Borneo. Alarmingly, the two new species of freshwater mussels are very rare, as each can only be found from a single stream in Borneo at very low densities. Considering these findings and the possible threat of anthropogenic habitat degradation, these two species could be at risk of extinction. The introduction of non-native freshwater mussel species, Sinanodonta cf. woodiana and Sinanodonta lauta into Borneo though human activities may further threaten many of the native freshwater mussels. Sinanodonta cf. woodiana is now the most common and widespread unionid species in Borneo. Therefore, this calls for an urgent protection and conservation of the native species of freshwater mussels in Borneo.

The study is published in the journal, Aquatic Conservation: Marine and Freshwater Ecosystems (https://doi.org/10.1002/aqc.3695).

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