Pastilla ruhuna

Binomial Name: Pastilla ruhuna

Pastilla ruhuna Ng & Tay, 2001 is an endemic species of freshwater crabs belongs to the monotypic genus of Pastilla. Population of this species is restricted to the southeastern wet zone of Sri Lanka. Also they live in burrows dug by them in the wet soil. According to IUCN Red list, it is in the category of ‘Endangered’ and conservation actions have to be taken to guarantee the future existence of this rare species.

Referances:

• The IUCN Red List of Threatened Species(tm) 2015-4 - http://www.iucnredlist.org
• Identification guide provided by - Sameera Akmeemana

Mahatha helaya

Binomial name: Mahatha helaya

Mahatha helaya is an endemic species of freshwater crabs found in the hill country of Sri Lanka. This crab is only known from its type locality, near Kalupahana in the borders of water streams close to the main Colombo-Haputale road (Bahir and Ng 2005). All the members of the genus Mahatha are endemic to the island and the species name 'helaya' also has a Sinhala meaning, which is a name for an inhabitant of Sri Lanka. In the IUCN Red list, it is 'Critically Endangerd' due to the very limited distribution.

Above photographed specimens were also found very close to the defined type locality, where margins of a roadside stream at Kalupahana. All human activities that change the aquatic environment of river margins will be the main risk for the survival of this species.

References:

• Bahir, Mohomed M., and Peter KL Ng 2005 Descriptions of Ten New Species of Freshwater Crabs (Crustacea: Brachyura: Parathelphusidae: Ceylonthelphusa, Mahatha, Perbrinckia) from Sri Lanka. Raffles Bulletin of Zoology, Supplement 12: 47–75.
• The IUCN Red List of Threatened Species(tm) 2015-4 - http://www.iucnredlist.org
• Identification guide provided by: Mr. M. M. Bahir

Sri Lanka red crab (Ceylonthelphusa sanguinea)

English: Sri Lanka red crab
Binomial: Ceylonthelphusa sanguinea
Sinhala: ශ්‍රී ලංකා රතු කකුළුවා[Sri Lanka rathu kakuluwa]

Sri Lanka red crab is an endemic species of freshwater crabs found in Knuckles Range. Its habitats are small streams and waterfalls in the misty mountains of the Knuckles region. Above photographed one was found in a small stream at about 11 a.m in November, 2015. It is observed that they hide inside rock crevices after some time. In the IUCN Red List of Threatened Species, this crab has been categorized as "Critically endangered" due to its very limited distribution.

Invasive species, rainwater acidification, climate change, and all other human activities that pollute aquatic environment systems are the threats for the existence of this species.

Information obtained from: Mr. M. M. Bahir. 
Reference: The IUCN Red List of Threatened Species(tm) 2015-4 - http://www.iucnredlist.org