Bathynomus jamesi Kou, Chen and Li, 2017 from Zhengbin fishing port in Keelung, Taiwan, was identified by the shape of the distolateral corner of the uropodal endopod, the shape of the clypeus, and the nucleotide sequences of the COI (cytochrome c oxidase subunit 1) and 16S rRNA genes. Only two species of Bathynomus have previously been recorded from Taiwan, B. doederleini Ortmann, 1894 and B. decemspinosus Shih, 1972. Bathynomus kensleyi, previously known from the South China Sea as well as the south-east Swain Reefs, Coral Sea, was primarily differentiated by the elongate and upturned pleotelson spines, but that character is now shown to also occur in mature Bathynomus jamesi. Two specimens from the Gulf of Mexico (obtained from the Enoshima Aquarium in Japan) were compared to species of Bathynomus from the western North Atlantic. Sequence data showed that one of two samples was not B. giganteus Milne-Edwards, 1879, as had been assumed, and it did not match any other species of Bathynomus. That specimen was collected off the Yucatán Peninsula and is morphologically distinct from both B. giganteus (in the relative length of the antennal flagellum and the length:width ratio of the pleotelson) and B. maxeyorum Shipley, Brooks, and Bruce in Shipley et al., 2016 (the number of pleotelson spines is seven and the distolateral corner is produced on the uropodal exopod). Therefore, it is here described as B. yucatanensis sp. nov. Bathynomus is currently a very minor fisheries resource in Taiwan and Japan, but this find demonstrates the continuing importance of the fishing industry to marine biological exploration. http://www.zoobank.org/urn:lsid:zoobank.org:pub:399605D3-356E-402D-9ED1-E36A649A3F1B

The red swamp crayfish Procambarus clarkii ( Girard, 1852) is an alien invasive species as well as a commercially exploited animal. The sterile-male-release technique (SMRT) using infertile but sexually active males has been an effective candidate measure to control this invasive crayfish. Additionally, the limited supply of juveniles due to females’ spawning seasonality hinders the further development of the P. clarkii aquaculture industry. Information on its reproductive biology, such mating strategies and factors affecting offspring production, is crucial for developing an effective SMRT and aquaculture systems for P. clarkii. We review the reproductive biology of this species in terms of 1) sexual dimorphism and reproductive status, 2) sex recognition, mating, and mate preferences, and 3) egg production, embryonic development, and hatching. Intra- and intersexual dimorphisms of chelae are evident in P. clarkii, and a reproductive morphotype (form I) with larger chelae and a non-reproductive morphotype (form II) with smaller chelae are detected in both females and males, allowing us to easily determine the reproductive status of both sexes. The crayfish exhibits mutual mate choice (i.e., preference for larger mates), and small-sized males reproductive potential is low. Female fitness (i.e., number of offspring) generally depends on their body size. Female brood care appears to promote early embryo development before the egg-nauplius stage. Further study is required to identify the maternal factors affecting early embryonic development, which may improve measures for controlling invasive populations and enhancing aquaculture productivity.

The range expansion of the red swamp crayfish (Procambarus clarkii) across Japan is reviewed and updated. A brief account of the diagnostic characters with a description of the mandible and gills of P. clarkii is provided with detailed illustrations.

International Association of Astacology Freshwater Crayfish - A Journal of Astacology