Jassa (Crustacea: Amphipoda): a new morphological and molecular assessment of the genus Author Conlan, Kathleen E. 0000-0002-2263-7075 kconlan@nature.ca Author Desiderato, Andrea 0000-0002-2263-7075 kconlan@nature.ca Author Beermann, Jan 0000-0002-2263-7075 kconlan@nature.ca text Zootaxa 2021 2021-03-04 4939 1 1 191 journal article 7102 10.11646/zootaxa.4939.1.1 ee8e66ff-2f2c-47e2-978b-be52996d5b0f 1175-5326 4580622 F33F42D0-A139-4CE3-97D7-1314C12CF86B Jassa calcaratus ( Rathke, 1843 ) In documenting the fauna of Norway , Rathke (1843) described and figured a new species which he had collected from seaweed at Kristiansund, Norway . Named Podocerus calcaratus , his illustration of the male’s long-thumbed gnathopod 2 indicates that it is probably Jassa falcata . Rathke (1843) indicated that P. calcaratus was close to, but different from P. pulchellus (now Jassa falcata ) but did not state why. Bate (1862) disagreed and synonymized P. calcaratus under P. pulchellus (now Jassa falcata ). Sars (1894) listed P. calcaratus as a synonym of P. falcatus (now Jassa falcata ) , saying that “The P. calcaratus of Rathke is undoubtedly the adult male of this species...” One large male specimen, collected at Tromsø, Norway , and identified as Podocerus calcaratus by Danielsen, (not type ), was lent by the Zoological Museum, Bergen, Norway (ZMUB 2832) for this study. The vial held a secondary label, Jassa pulchella . This specimen was clearly a major form male J. falcata . Although the whereabouts of the type specimens are unknown, it is clear from Rathke’s (1843) description, illustrations and collection location that his P. calcaratus is indeed J. falcata ( Montagu, 1808 ) . Therefore, J. calcaratus is synonymized with J. falcata .