Johora singaporensis

Ecology

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.

Distribution

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.

J. singaporensis is one of three freshwater crabs that are endemic to Singapore. The others are Irmengardia johnsoni, and the critically endangered Parathelphusa reticulata.

Phylogeny

The relatives of J. singaporensis 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.

Status

Johora singaporensis is listed by the International Union for Conservation of Nature as Critically Endangered under criteria B1ab(iii)+2ab(iii), 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.

References

References

1. Esser, L.J.. (2008). "''Johora singaporensis''".
2. (2008). "Systema Brachyurorum: Part I. An annotated checklist of extant Brachyuran crabs of the world". [[Raffles Bulletin of Zoology]].
3. "Organisms described from Singapore". Raffles Museum of Biodiversity, [[National University of Singapore]].
4. "Where can we find biodiversity in Singapore?". Raffles Museum of Biodiversity, [[National University of Singapore]].
5. (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]].
6. (2009). "Freshwater crabs and the biodiversity crisis: Importance, threats, status, and conservation challenges". [[Biological Conservation (journal).
7. Harvey. (September 10, 2012). "The expendables? World's 100 most endangered species listed". [[The Guardian]].
8. (November 2017). "Priceless or Worthless?". [[Zoological Society of London]].