The freshwater shrimp family Euryrhynchidae Holthuis, 1950 (Crustacea: Decapoda: Caridea) revisited, with a taxonomic revision of the genus Euryrhynchus Miers, 1878 Author Pachelle, Paulo P. G. Author Tavares, Marcos text Zootaxa 2018 2018-02-19 4380 1 journal volume 30720 10.11646/zootaxa.4380.1.1 099d3015-8af8-4ae1-b667-1ac61dde9294 1175-5326 1175650 9DC29ECD-8C44-4F42-BA0E-9B0C830A7C73 Genus Euryrhynchina Powell, 1976 Euryrhynchina Powell, 1976 : 894 . Gender feminine. Euryrhynchina — Powell 1977 : 650; Holthuis 1993 : 183; Pereira 1997 : 3, tab. 5; De Grave 2007 : 193; De Grave et al. 2008 : 291; De Grave et al. 2009 : 16; De Grave & Fransen 2011 : 309; De Grave et al. 2015 : 4; De Grave et al. 2017 : 121. Recognition characters. Rostrum smooth, non-dentate on both dorsal and ventral margins. Distomesial region of ocular peduncles produced anteriorly, reaching or overreaching distal margin of cornea. Distolateral margin of stylocerite smooth, without cluster of setae. Accessory ramus of antennule with aesthetacs restricted to distal article. Third maxilliped without arthrobranch. Third and fourth pereopod carpus without cuspidate seta on distoventral margins. Third to fifth pereopod dactyli without cuspidate setae on dorsal margins. Male second pleopod with endopod spatulate, not modified into gonopod, fringed with plumose setae, appendix masculina present. Uropodal exopod with 1 to 3 cuspidate setae on diaeresis, increasing in size towards lateral margin. Type species. Euryrhynchina edingtonae Powell, 1976 , by monotypy. Species included. Euryrhynchina edingtonae and Euryrhynchina puteola De Grave, Piscart, Tuekam Kayo & Anker, 2017 . Distribution. Nigeria ( Edo State, Delta State, Rivers State) and Cameroon ( Littoral province) ( Powell 1976 ; Victor & Ogbeibu 1985 ; Pereira 1997 ; Ogbeibu & Oribhabor 2002 ; Ikomi et al . 2005 ; Olomukoro 2009 ; Olomukoro & Dirisu 2014 ; De Grave et al. 2017 ; present study) ( Figs. 2 , 62B , yellow and orange circles). Remarks. The Euryrhynchina are the smallest representatives of the family Euryrhynchidae , with adult specimens up to 4.1 mm of carapace length (based on known specimens). Euryrhynchina is unique within the family in having short ocular peduncles with mesial margin produced anteriorly, absence of arthrobranch on the third maxilliped, male second pleopod with spatulate endopod, and uropodal diaeresis with up to 3 cuspidate setae. Upon the discovery of a second species in the genus, E. puteola , the presence of a cluster of setae on the distomesial region of ocular peduncles, the shape of scaphocerite and the presence of spiniform seta on third to fifth pereopod merus are no longer diagnostic for the genus, as postulated previously by Powell (1976) . The West African genus Euryrhynchina and the South American genus Euryrhynchus share two exclusive diagnostic characters, such as the smooth, non-dentate rostrum and the accessory ramus of antennule with aesthetascs restricted to the distal article ( Figs. 3 A , 9 A , C , 10D–G ). Curiously, Euryrhynchina does not share a single exclusive diagnostic character with the also West African Euryrhynchoides , granted that the presence of an appendix interna on the second female pleopod (a character until now supposedly restricted to these genera, see Powell 1976 : figs. 3I , 7H) also occurs in one of the Euryrhynchus species (see Euryrhynchus tuyuka sp. nov. ).