Taxonomic, ecological and morphological diversity of Ponto-Caspian gammaroidean amphipods: a review Author Copilaș-Ciocianu, Denis Author Sidorov, Dmitry text Organisms Diversity & Evolution 2022 New York, N. Y. 2022-01-07 22 2 285 315 http://dx.doi.org/10.1007/s13127-021-00536-6 journal article 10.1007/s13127-021-00536-6 1618-1077 13366423 Key to species of Dikerogammarus 1. Pleosome segments keeled ........................ D. caspius - Pleosome segments flat .............................................. 2 2. Urosomal tubercles low ............................ D. fluviatilis * - Urosomal tubercles columnar, well developed .......... 3 3. Antenna 1 accessory flagellum bi-articulated ... D. gruberi - Antenna 1 accessory flagellum 4 or more articles ...... 4 4. Propodi of gnathopods 1 and 2 with mid-palmar spine .................................................................. D. aralychensis * - Propodi of gnathopods 1 and 2 without mid-palmar spine ................................................................................. 5 5. Medial surface of pereopod 7 basis with setae ......... 6 - Medial surface of pereopod 7 basis without setae ..... 7 6. Antenna 2 peduncular segments with numerous clusters of setae longer than the underlying segment ... D. bispinosus - Antenna 2 peduncular segments with few clusters of setae shorter than the underlying segment ... D. istanbulensis 7. Propodi of gnathopods 1 and 2 with setae as long as propodus width .................................................. D. villosus - Propodi of gnathopods 1 and 2 with setae much shorter than propodus width ......................................................... 8 8. Uropod 3 exopod with spines on inner and outer margins .......................................................... D. haemobaphes - Uropod 3 exopod without spines .................. D. oskari .