Johora singaporensis, the Singapore stream crab or Singapore freshwater crab, is a critically endangered species of freshwater crab endemic to Singapore. It grows to a size of 30 millimetres (1.2 in) wide.
J. singaporensis lives in streams running through undisturbed forest, where it hides under rocks at the stream's edge, or inside aggregations of leaves and detritus. It is mostly nocturnal, feeding on detritus and oligochaete worms which live in the muddy stream bed.
J. singaporensis only lives in Singapore, and has only ever been recorded from two locations. One of these was inside Bukit Timah Nature Reserve, but that population is believed to have been extirpated, as recent surveys have failed to find any examples there. The second population is outside the nature reserve at Bukit Batok, partly on private land, and partly on military land. Acidification of the first stream may have caused the first population to die out, while a lowering of the water table in the second stream threatens the second population.
The relatives of J. sinaporensis in the genus Johora are found across the Straits of Johor on the adjacent Malay Peninsula and some offshore islands, making J. singaporensis the southernmost species in the genus. It probably forms the sister group to a clade comprising J. tiomanensis, J. counsilmani, J. murphyi, J. johorensis, J. gapensis and J. intermedia, from which it separated about 5 million years ago, at a time when the eustatic changes in global sea level may have opened up a land bridge to Singapore.
Johora singaporensis is listed by the International Union for Conservation of Nature as Critically Endangered under criteria B1ab(iii)+2ab(iii), which refer to the small size of the remaining populations and the ongoing deterioration of the habitat. The species' restriction to a single small island is likely to have increased the threat of extinction. In 2012, it was included among the world's 100 most threatened species, in a report by the IUCN Species Survival Commission and the Zoological Society of London.
- Lara Esser, Neil Cumberlidge & Darren Yeo (2008). "Johora singaporensis". IUCN Red List of Threatened Species. Version 3.1. International Union for Conservation of Nature. http://www.iucnredlist.org/apps/redlist/details/134219. Retrieved February 3, 2010.
- Peter K. L. Ng, Danièle Guinot & Peter J. F. Davie (2008). "Systema Brachyurorum: Part I. An annotated checklist of extant Brachyuran crabs of the world" (PDF). Raffles Bulletin of Zoology 17: 1–286. http://rmbr.nus.edu.sg/rbz/biblio/s17/s17rbz.pdf.
- "Organisms described from Singapore". Raffles Museum of Biodiversity, National University of Singapore. http://rmbr.nus.edu.sg/nis/dfs_animal.html. Retrieved November 4, 2010.
- "Where can we find biodiversity in Singapore?". Toddycats! Museum Fest 2002. Raffles Museum of Biodiversity, National University of Singapore. http://rmbr.nus.edu.sg/toddycats/museumfest/text.html. Retrieved February 3, 2010.
- Darren C. J. Yeo, Hsi-Te Shih, Rudolf Meier & Peter K. L. Ng (2007). "Phylogeny and biogeography of the freshwater crab genus Johora (Crustacea: Brachyura: Potamidae) from the Malay Peninsula, and the origins of its insular fauna". Zoologica Scripta 36 (3): 255–269. doi:10.1111/j.1463-6409.2007.00276.x.
- Neil Cumberlidge, Peter K.L. Ng, Darren C.J. Yeo, Celio Magalhães, Martha R. Campos, Fernando Alvarez, Tohru Naruse, Savel R. Daniels, Lara J. Esser, Felix Y.K. Attipoe, France-Lyse Clotilde-Ba, William Darwall, Anna McIvor, Jonathan E.M. Baillie, Ben Collen & Mala Ram (2009). "Freshwater crabs and the biodiversity crisis: Importance, threats, status, and conservation challenges". Biological Conservation 142 (8): 1665–1673. doi:10.1016/j.biocon.2009.02.038.
- Fiona Harvey (September 10, 2012). "The expendables? World's 100 most endangered species listed". The Guardian. http://www.guardian.co.uk/environment/2012/sep/11/100-most-endangered-species-listed. Retrieved September 22, 2012.
- Jonathan E. M. Baillie & Ellen R. Butcher (2012). "Johora singaporensis, Singapore freshwater crab" (PDF). Priceless or Worthless?. Zoological Society of London. pp. 48–49. ISBN 978-0-900881-67-1. http://static.zsl.org/files/priceless-or-worthless-final-wq-2040.pdf.