Morphological and genetic differentiations revealed a new freshwater species of Gammarus from the French Pyrenees Author Piscart, Christophe 0000-0002-4054-4542 University of Rennes, CNRS, ECOBIO - UMR 6553, F- 35000, Rennes, France Author Blanchet, Simon 0000-0002-3843-589X CNRS, Station d’Écologie Théorique et Expérimentale du CNRS, UAR- 2029, 2 route du CNRS, F- 09200 Moulis, France text Zootaxa 2026 2026-02-05 5757 3 279 293 http://dx.doi.org/10.7717/peerj.20736 journal article 314923 10.11646/zootaxa.5757.3.5 7f24e593-8f4f-4a9c-934e-01237ad9a74a 1175-5326 19173745 AF0F4EC6-A15F-4763-86D2-F7B6014E3C18

TABLE 2. Geographical distribution and morphological characteristics of freshwater Gammarus species possessing long setae on the anterior margins of pereopods 5–7, and an uropod 3 endopodite that is shorter than or equal to 50% of the exopodite.

	G. ariegiensis sp. nov.	G. orinos	G. stupendus	G. rouxi	G. birsteini
Geographical distribution	French Pyrenees Mountains	French Central Massif	South-East France, St Baume Massif	Morocco, Middle Atlas	East Turkey, Caucasus Mountains
Setae on articles 4 and 5 of antenna 2	3–4 groups of setae shorter or as long as article width	5–6 groups of setae longer than article width	5–6 groups of setae longer than article width	3–4 groups of setae shorter or as long as article width	8–10 groups of setae longer than article width
Calceoli	absent	present	absent	present	absent
Setae on margin of uropod 3	simple/plumose	simple	simple	simple/plumose	simple
Number of apical spines on telson	3	2–3	1	2	1
Basal article of pereopod 7	Short setae without distal constriction	Short setae without distal constriction	Short setae without distal constriction	Long setae with distal constriction	Short setae without distal constriction