Monday, August 28, 2017

[Crustacea • 2017] Terrapotamon thungwa • A Second New Species of Terrestrial Long-legged Terrapotamon Ng, 1986 (Brachyura: Potamidae) from Karst Forests in Peninsular Thailand


 Terrapotamon thungwa
Promdam, Yeesin & Ng. 2017

ปูเขาหินปูนทุ่งหว้า || RAFFLES BULLETIN OF ZOOLOGY. 65 

 Abstract
 A new species of potamid crab of the genus Terrapotamon Ng, 1986, is described from karst forests in Satun, Peninsular Thailand. Terrapotamon thungwa n. sp. has very long ambulatory legs and superficially resembles T. longitarsus, the only other long-legged species in the genus. They can easily be distinguished by life colouration, carapace features, as well as structures of the epistome, male thoracic sternum, cheliped and male first gonopod. 

Key words: Freshwater crab, new species, Potamidae, Peninsular Thailand, karst, caves, taxonomy

TAXONOMY
Family Potamidae Ortmann, 1896
Subfamily Potamiscinae Bott, 1970, sensu Yeo & Ng, 2004
Genus Terrapotamon Ng, 1986

Terrapotamon thungwa n. sp.

Fig. 1. Terrapotamon thungwa n. sp., colour in life from Satun, Thailand.
A–C, holotype male (44.6 × 35.0 mm) (ZRC 2016.0595).

Fig. 8. Terrapotamon thungwa n. sp., observed in the cave at Ban Namtok Than Plio, Amphoe Thung Wa, Satun, Thailand. A, paratype male (41.1 × 33.3 mm) (PSUZC-CRU-0072).

Fig. 8. Terrapotamon thungwa n. sp., observed in the cave at Ban Namtok Than Plio, Amphoe Thung Wa, Satun, Thailand.  B, C, paratype female (29.4 × 23.8 mm) (PSUZC-CRU-0073).

Fig. 9B, Terrapotamon thungwa n. sp., specimen observed in cave in Ban Namtok Than Plio, Amphoe Thung Wa, Satun, Thailand.

Fig. 6. Terrapotamon longitarsus  Lheknim & Ng, 2016 paratype male (40.8 × 32.5 mm) (PSUZC 20150726-01.01), Satun, Thailand.

Etymology. The name is derived from the type locality at Amphoe Thung Wa. The name is used as a noun in apposition. 

Remarks. The long ambulatory legs of T. thungwa n. sp. is a character shared only by one other species of Terrapotamon, T. longitarsus Lheknim & Ng, 2016, also from the Satun area in Peninsular Thailand. It is surprising to find two similar species occurring in the same area, but the differences between the two species are very marked and leave no doubt they are separate taxa. Terrapotamon thungwa can most easily be separated in its bright red overall coloration in life (Figs. 1, 8A) (purple in T. longitarsus; Fig. 6); ....

Habitat. All the specimens of Terrapotamon thungwa were obtained from the karst landscape of Satun. From the material collected, it would appear that the area and habitat where T. thungwa occurs overlaps with T. longitarsus. Both species were found inside and outside the caves as well as in the karst forest. In the dark zone inside the cave, adults of T. thungwa were observed climbing on the cave walls (Fig. 8B, C), with a small specimen observed in a pool on the cave floor (Fig. 9A, B). Up to five specimens have been observed on the cave floor. Adult males of both two species were observed in rock pools at the bottom of deep crevices in the karst forest, while a small specimen of T. longitarsus were seen at a sheltered rock pool near the cave entrance (Fig. 9C, D). The crabs use these collected pools to replenish their gill chambers.



  

Rueangrit Promdam, Pun Yeesin and Peter K. L. Ng. 2017. A Second New Species of Terrestrial Long-legged Terrapotamon Ng, 1986 (Crustacea: Brachyura: Potamidae) from Karst Forests in Peninsular Thailand. RAFFLES BULLETIN OF ZOOLOGY. 65; 404–415.

Vachira Lheknim and Peter K.L. Ng. 2016. A New Species of Long-legged Terrestrial Terrapotamon Ng, 1986 (Crustacea: Brachyura: Potamidae) from Limestone Formations in Satun, southern Thailand.  Zootaxa. 4200(1); 143–152. DOI: 10.11646/zootaxa.4200.1.6  ResearchGate.net/publication/311004094_A_new_species_of_Terrapotamon_from_Satun_southern_Thailand

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