Eogammarus (Bousfield, 1979)

Tomikawa, Ko, Morino, Hiroshi, Toft, Jason & Mawatari, Shunsuke F., 2006, A revision of Eogammarus Birstein, 1933 (Crustacea, Amphipoda, Anisogammaridae), with a description of a new species, Journal of Natural History (J. Nat. Hist.) 40 (17 - 18), pp. 1083-1148 : 1145-1146

Key to the species of Eogammarus

1. Urosomite 2 with four clusters of robust setae........... 2

– Urosomite 2 with two clusters of robust setae........... 3

2. Posterior margin of peduncular articles 4 and 5 each with 0–1 setal pair or cluster. Telson as long as wide.............. E. turgimanus

– Posterior margin of peduncular articles 4 and 5 each with 2–6 setal pairs or clusters. Telson longer than wide.............. E. ryotoensis

3. Pereopods 3–7 with numerous plumose setae. Ventral margin of epimera 2 and 3 with numerous plumose setae. Retinacula on pleopods triplicated..... 4

– Pereopods 3–7 with simple setae. Ventral margin of epimera 2 and 3 with simple setae. Retinacula on pleopods paired.............. 5

4. Aesthetascs on antenna 1 shorter than surrounding setae. Calceoli on antenna 2 wider than 0.25× width of respective flagellar article.... E. psammophilus

– Aesthetascs on antenna 1 longer than surrounding setae. Calceoli on antenna 2 narrower than 0.25× width of respective flagellar article..... E. schmidti

5. Peduncular article 1 of antenna 2 lacking robust setae. Outer margin on palp article 1 of maxilla 1 with setae................. 6

– Peduncular article 1 of antenna 2 with robust setae. Outer margin on palp article 1 of maxilla 1 lacking setae................ 10

6. Pleonites dorsally carinate.............. E. tiuschovi

– Pleonites dorsally smooth................. 7

7. Peduncular article 1 of antenna 1 with slender posterodistal seta. Posterior setae on bases of pereopods 6 and 7 shorter than half width of ischium. Ventral margins of epimera 2 and 3 with robust setae only.......... E. possjeticus

– Peduncular article 1 of antenna 1 with robust posterodistal seta. Posterior setae on bases of pereopods 6 and 7 longer than half width of ischium. Ventral margins of epimera 2 and 3 with slender or slender+robust setae......... 8

8. Flagellar articles on antenna 1 each with two aesthetascs.... E. itotomikoae

– Flagellar articles on antenna 1 each with one aesthetasc........ 9

9. Longest posterior seta on basis of male pereopod 7 shorter than width of ischium. Robust apical setae on telson shorter than slender apical setae.... E. kygi

– Longest posterior seta on basis of male pereopod 7 longer than width of ischium. Robust apical setae on telson longer than slender apical setae... E. barbatus

10. Antenna 2 of female with calceoli. Robust apical setae on telson shorter than slender apical setae or as long as slender apical setae..... E. confervicolus

– Antenna 2 of female lacking calceoli. Robust apical setae on telson longer than slender apical setae................. E. oclairi