Pseudodiaptomidae G.O. Sars., 1902

The family Pseudodiaptomidae G.O. Sars, 1902 includes three genera: Calanipeda Kritschagin, 1873, Pseudodiaptomus Herrick, 1884, and Archidiaptomus Madhupratap and Haridas, 1978. The genera Calanipeda and Archidiaptomus are both monotypic, consisting of Calanipeda aquaedulcis and Archidiaptomus arroorus respectively, whereas the genus Pseudodiaptomus includes 78 valid species (Walter and Boxshall, 2023). Pseudodiaptomusis divided up into seven species groups, and eight species subgroups can be distinguished based on the key to species groups and subgroups reported (Walter, 1986a; Walter et al., 2006; Srinui et al., 2013). Calanipeda aquaedulcis is a freshwater euryhaline species and usually occurs in rivers, lakes, and estuaries around the Mediterranean Sea, Black Sea, and Caspian Sea regions as well as Spanish, and Portuguese waters (Razouls et al., 2005–2023). Archidiaptomus arroorus is found in brackish coastal waters of India (Madhupratap and Haridas, 1978). Pseudodiaptomus species are spread over a broad latitudinal range worldwide and are typically found in tropical and temperate shallow coastal and estuarine waters (Walter, 1989). They usually occur in a range of salinity, from hypersaline, marine to freshwaters (Walter, 1986a). To date, in both the ICES areaand the Black Sea, among Pseudodiaptomidae species, Pseudodiaptomus marinus Sato, 1913and C. aquaedulcis occur, whereas in the Mediterranean Sea these two species occur in addition to Pseudodiaptomus salinus Giesbrecht, 1896, Pseudodiaptomus trihamatus Wright S., 1937, Pseudodiaptomus australiensis Walter, 1987, and Pseudodiaptomus arabicus Walter, 1998. (Razouls et al., 2005–2023).A key modified from Boxshall and Halsey (2004) for the identification of the three genera included in the family Pseudodiaptomidae, a key for the identification of the five species included in the genus Pseudodiaptomus, and the morphological features of C. aquaedulcis are presented. The aim of this leaflet is to help with the morphological identification of the species of Pseudodiaptomidae present in the ICES area as well as in the adjacent Ponto-Mediterranean region and to provide their geographic distribution. This is a new leaflet and shows an unedited stereomicroscope image of a P. marinus egg-carrying female