Thursday, June 1, 2023

[Crustacea • 2023] Demanietta sunthorni • A New Species of Freshwater Crab (Decapoda: Brachyura: Potamidae) from Adang-Rawi Island Group, Andaman Sea, south Thailand

Demanietta sunthorni 
Lheknim, Leelawathanagoon & Ng, 2023


 A new species of a potamid crab belonging to the genus Demanietta Bott, 1966, is described from Adang Island, Andaman Sea, off Satun, south Thailand. Demanietta sunthorni, new species, belongs to a group of Demanietta species which has a distinct epibranchial tooth, and strong epigastric and postorbital cristae on the carapace. It can be distinguished from all congeners most easily by the form of the male first gonopod which is slender, with the terminal segment sinuous, upcurved and possessing a large dorsal fold. This is the southernmost record of the genus. 

Key words. Satun Province, Tarutao National Park, Isthmus of Kra, Potamoidea, taxonomy, new species

Family Potamidae Ortmann, 1896 
Subfamily Potamiscinae Bott, 1970 sensu Yeo & Ng (2004)

Demanietta sunthorni, new species
Colour in life of holotype male (36.6 × 27.7 mm) (ZRC 2022.0826), Thailand.

Demanietta sunthorni, new species

Diagnosis. Carapace subquadrate, width to length ratio 1.26– 1.32; dorsal surface relatively low, not inflated; frontal region with numerous blunt granules (Figs. 2, 3A–D); epigastric cristae clearly demarcated, area with mix of granules and rows of transverse striae; postorbital cristae distinct, sharp, separated from epigastric cristae by distinct gap; postorbital cristae joining epibranchial tooth by uneven granulated ridge; external orbital tooth triangular with outer margin longer than inner margin, clearly separated from epibranchial tooth by small cleft; epibranchial tooth distinct, triangular (Fig. 3B); posterior part of anterolateral region and posterolateral region with distinct transverse striae; subhepatic, suborbital and pterygostomial regions with distinct striae and granules (Fig. 3C); posterior margin of epistome with distinct acutely triangular median tooth (Fig. 3C, D); third maxilliped ischium subrectangular, ...

Etymology. The species is named after the late Assoc. Prof. Sunthorn Sotthibandhu, an eminent entomologist of the Biology Department, Faculty of Science, Prince of Songkla University (PSU). He used to be the head of the Department of Biology, as well as PSU President, and President of Songkhla Rajabhat University. The first author has known Ajarn Sunthorn for nearly 40 years, since he was an undergraduate student in his class. He was the first one who taught the first author the beauty of science and how it works. He has been an excellent colleague and a wonderful collaborator on teaching and science, and the many insightful discussions with him will be missed. After his retirement, he continued with research on the philosophy of science and kept working on this topic to his last day. He will be sorely missed. The specific epithet is derived from his first name, Sunthorn.

Vachira Lheknim, P. Leelawathanagoon and Peter K. L. Ng. 2023. Demanietta sunthorni, A New Species of Freshwater Crab (Crustacea: Decapoda: Brachyura: Potamidae) from Adang-Rawi Island Group, Andaman Sea, south Thailand. RAFFLES BULLETIN OF ZOOLOGY. 71; 377–386.