PSU and NUS researchers discover new freshwater crab species “Todaeng Vampire crab” in Narathiwat
A team of researchers described and named a new freshwater crab species: Geosesarma todaeng. Mr. Pun Yeesin, researcher at the Faculty of Science and Technology; Mr. Rueangrit Promdam, scientist at Princess Maha Chakri Sirindhorn Natural History Museum; in collaboration with Prof. Dr. Peter Ng from Lee Kong Chian Natural History Museum, National University of Singapore, chose the name as a reference to the place where this species was found: Ban To Daeng, Sungai Kolok, Narathiwat province. Previously, two genera of this crab were reported in Thailand, namely G. krathing from Chanthaburi province, and G. serenei from Nakhon Si Thammarat province.
The colloquially named Todaeng Vampire crab was discovered in a swamp forest ecosystem. Most are found on Lum Phee trees, a palm-family plant. The new species looks similar to other members of the geosesarma genus, with a square carapace and yellow or orange front claws. The back half of the carapace and walking legs are dark, black, grey, or brown, while the eyes are black with gray specks. This is the first time a member of this species has been discovered living in a lowland forest near sea level.
Almost all species of the geosesarma genus become terrestrial crabs throughout their life cycle; small hatchlings stay within the abdomen of the mother crab without having to live as planktonic larvae in the water. The crab derives water from a diet consisting of insects and plant parts, and continues to use temporary water sources in the forest for respiration and gaseous exchange in their gills, a trace of its origin as an aquatic animal.
It is possible that the same crab genus exists in other areas of Southern Thailand, but that has yet to be investigated and reported.
Publication
Ng.
P.K.L., P. Yeesin, and R. Promdam. 2023. A new species of vampire crab
(Crustacea: Brachyura: Sesarmidae: Geosesarma) from a freshwater swamp
forest in Narathiwat Province, Southern Thailand, with a note on
Geosesarma serenei Ng, 1986. Tropical Natural History, 23(2023):
97–104.