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 Euryrhynchus amazoniensis Tiefenbacher, 1978 ( Figs. 8–23 , 63A ) Euryrhynchus amazoniensis Tiefenbacher, 1978 : 183 , fig. 2a, b [ partim ]. Euryrhynchus amazoniensis — Holthuis 1966 : 6, figs. 2, 3 [as E. burchelli Calman, 1907 ]; Irmler, 1975 : 391 [as E. burchelli Calman, 1907 , partim ]; Gomes Corrêa 1980 : 257, figs. 1–9 [as E. wrzesniowskii Miers, 1878 ]; Kensley & Walker 1982 : 2, tabs. 2, 3, figs. 1, 2 [ partim ?]; Coelho & Ramos-Porto 1985 : 408 (tab. I); Walker & Ferreira 1985 : 266, tab. 1 [ partim ?]; Magalhães 1988 : 46, tab. I, figs. 27–43 [ partim ]; Magalhães & Walker 1988 : 281, tab. I [ partim ]; Ramos-Porto & Coelho 1990 : 108; Odinetz Collart & Magalhães 1994 : 2460, tab. 1, 2, fig. 5 [ partim ?]; Walker 1994 : 77, fig. 11 [ partim ?]; Pereira & García 1995: 117, tab. 1; López & Pereira 1998 : 77; Ramos-Porto & Coelho 1998 : 330; Walker 2001 : 565 [ partim ?]; Magalhães 2002 : 1099; García-Dávila & Magalhães 2003 : 665, figs. 1–3, 55; Melo 2003 : 322, figs. 174, 175; De Grave 2007 : 193; Magalhães & Pereira 2007 : 114, tabs. 1–4; Vieira 2008 : 67, fig. 5.1a, tab. 5.1; Kemenes et al. 2010 : 37, fig. 3; Valencia & Campos 2010 : 222, figs. 1, 2; De Grave & Fransen 2011 : 309; Vogt 2013 : 91; Moscoso 2012 : 12, 43; Pimentel & Magalhães 2014 : 1302, fig. 2; Ashelby et al. 2015 : 16; De Grave et al. 2015 : 3, fig. 1; Santos et al. 2018 : 23, figs. 1F–J, 7. Euryrrhynchus amazoniensis — Vieira 2003 : 59, figs. 3.3, 3.4 [ lap. cal. ]. Euryrhynchus amazonensis — Pereira 1991 : 83, fig. 8; Pereira 1997 : 51 (tab. 6), figs. 1, 5A, 15A, 16D, 27B, 29H, 38D, 39, 40, 41; Delgado et al. 1997 : 16 [ lap. cal. ]. Eyryrhynchus amazoniensis — Santos et al. 2018 : fig. 7 [ lap. cal. ]. FIGURE 8. A–C, Euryrhynchus amazoniensis Tiefenbacher, 1978 : (A) male (cl 6.6 mm), Igarapé Tubana, tributary of Rio Jufari, Amazonas, Brazil (MZUSP 34523), lateral view; (B) male (cl 6.0 mm), same lot as previous specimen, lateral view; (C) ovigerous female (cl 4.9 mm), same lot as previous specimen, lateral view. Photographs kindly provided by Joel Braga de Mendonça Jr. FIGURE 9. A–I, Euryrhynchus amazoniensis Tiefenbacher, 1978 : (A–H) male (cl 7.5 mm), Barcelos, Amazonas, Brazil (MZUSP 20014); (I) female (cl 5.7 mm), Igarapé Japiina, Amapá, Brazil (MZUSP 21431). (A) Anterior region of the body, dorsal view; (B) Same, eye and part of frontal margin of carapace, setae omitted; (C) same, lateral view; (D) Pereon, fourth to eighth sternites, ventral view; (E) Same, fourth sternite of pereon, median region, vental view; (F) Same, fifth sternite of pereon, median region, vental view; (G) Pleon, lateral view, setae omitted; (H) Same, sixth sternite of pleon, ventral view; (I) Pleon, lateral view, setae omitted. FIGURE 10. A–C, Euryrhynchus amazoniensis Tiefenbacher, 1978 : (A, F) male holotype (cl 5.0 mm), Ilha do Careiro, southeast of Manaus, Amazonas, Brazil (ZSM 406/1); (B, G) male (cl 2.5 mm), Igarapé Santa Fé, Amazonas, Brazil (MZUSP 34520); (C) male (cl 8.4 mm), tributary of Rio Mavaca, Amazonas, Brazil (USNM 221874); (D, E, H) male (cl 7.5 mm), Barcelos, Amazonas, Brazil (MZUSP 20014). (A–C) Anterior region of the body, lateral view; (D) Right antennule, mesial view; (E) Same, ventral view; (F, G) Same, main and accessory rami, ventral view; (H) Right antena, ventral view, setae on scaphocerite omitted. FIGURE 11. A–G, Euryrhynchus amazoniensis Tiefenbacher, 1978 : (A, B, D) male (cl 7.5 mm), Barcelos, Amazonas, Brazil (MZUSP 20014); (C) female (cl 5.7 mm), Igarapé Japiina, Amapá, Brazil (MZUSP 21431); (E) male (cl 2.5 mm), Igarapé Santa Fé, Amazonas, Brazil (MZUSP 34520); (F, G) male holotype (cl 5.0 mm), Ilha do Careiro, southeast of Manaus, Amazonas, Brazil (ZSM 406/1). (A) Telson, dorsal view, distal plumose setae omitted; (B) Same, distal region, dorsal view; (C) Telson, dorsal view, setae omitted; (D) Right uropodo, dorsal view, distal plumose setae omitted; (E) Same, exopod and part of protopodite, dorsal view, setae omitted; (F) Same, lateral process of protopodite, dorsal view, setae omitted; (G) Same, diaeresis of exopod, dorsal view, setae omitted. FIGURE 12. A–J, Euryrhynchus amazoniensis Tiefenbacher, 1978 : male (cl 7.5 mm), Barcelos, Amazonas, Brazil (MZUSP 20014). (A) Labrum, ventro-lateral view; (B) Same, ventral view; (C) Right mandible, outer (frontal) view; (D) Same, mesial view; (E) Left mandible, outer (frontal) view; (F) Same, mesial view; (G) Left maxillule, outer (frontal) view; (H) Right maxilla, outer (frontal) view; (I) Left first maxilliped, inner (caudal) view; (J) Same, outer (frontal) view. FIGURE 13. A–E, Euryrhynchus amazoniensis Tiefenbacher, 1978 : male (cl 7.5 mm), Barcelos, Amazonas, Brazil (MZUSP 20014). (A) Right second maxilliped, outer (frontal) view; (B) Right third maxilliped, lateral view; (C) Same, ultimate and part of penultimate article, mesial view; (D) Right first pereopod, lateral view; (E) Same, chela, dorsal (mesial) view. FIGURE 14. A–E, Euryrhynchus amazoniensis Tiefenbacher, 1978 : male (cl 7.5 mm), Barcelos, Amazonas, Brazil (MZUSP 20014). (A) Right second pereopod, lateral view; (B) Same, chela and carpus, dorsal (mesial) view; (C) Same, carpus and distal region of merus, mesial view; (D) Left second pereopod, lateral view; (E) Same, chela and carpus, dorsal (mesial) view. FIGURE 15. A–E, Euryrhynchus amazoniensis Tiefenbacher, 1978 : (A, B) male (cl 6.3 mm), Igarapé Santa Fé, Amazonas, Brazil (MZUSP 34520); (C, D) male (cl 2.5 mm), same lot as previous specimen; (E) male holotype (cl 5.0 mm), Ilha do Careiro, southeast of Manaus, Amazonas, Brazil (ZSM 406/1). (A) Right second pereopod, lateral view; (B) Same, chela and carpus, dorsal (mesial) view; (C) Right second pereopod, lateral view; (D) Same, chela and carpus, dorsal (mesial) view; (E) Right second pereopod, dorsal (mesial) view, setae and granules omitted. FIGURE 16. A–J, Euryrhynchus amazoniensis Tiefenbacher, 1978 : male (cl 7.5 mm), Barcelos, Amazonas, Brazil (MZUSP 20014). (A) Right third pereopod, lateral view; (B) Same, dactylus and distal region of propodus, lateral view; (C) Same, propodus and dactylus, ventral view; (D) Right fourth pereopod, lateral view; (E) Same, dactylus and distal region of propodus, lateral view; (F) Same, mesial view; (G) Same, propodus and dactylus, ventral view; (H) Right fifth pereopod, lateral view; (I) Same, dactylus and distal region of propodus, lateral view; (J) Same, propodus and dactylus, ventral view. FIGURE 17. A–M, Euryrhynchus amazoniensis Tiefenbacher, 1978 : (A–H) male (cl 7.5 mm), Barcelos, Amazonas, Brazil (MZUSP 20014); (I–M) female (cl 5.7 mm) Igarapé Japiina, near Porto Grande, Amapá, Brazil (MZUSP 21431). (A) Right first pleopod, ventral view; (B) Right second pleopod, ventral view; (C) Same, gonopod (endopod) and exopod, dorsal view; (D) Same, lateral view; (E) Same, mesial view; (F) Right third pleopod, ventral view; (G) Right fourth pleopod, ventral view; (H) Right fifth pleopod, ventral view; (I) Right first pleopod, ventral view; (J) Right second pleopod, ventral view; (K) Right third pleopod, ventral view; (L) Right fourth pleopod, ventral view; (M) Right fifth pleopod, ventral view. Distal setae omitted. FIGURE 18. A–I, Euryrhynchus amazoniensis Tiefenbacher, 1978 : male, Igarapé Tubana, tributary of Rio Jufari, Amazonas, Brazil (MZUSP 34524). (A) Anterior region of the body, lateral view; (B) Same, detail of frontal margin, lateral view; (C) Same, dorsal view; (D) Fourth sternite of pereon, median region, ventral view; (E) Fifth sternite of pereon, median region, ventral view; (F) Sixth and seventh sternites of pereon, median region, ventral view; (G) Right antennule, ventral view; (H) Same, distal article of accessory ramus of upper flagellum, dorso-lateral view; (I) Same, stylocerite, lateral view. Material examined. Holotype : ♂ (cl 5.0 mm), ZSM 406/1 , Brazil , Amazonas , about 30 km southeast from Manaus , Ilha do Careiro , coll. Antonio , xii.1965 . Paratypes : Brazil : 2♂ , ZSM 407 /2, Pará , right bank of Rio Cupari , near the mid-length of river, Igarapé do Caxias , among submerse leaflitter and tree branches, coll. H. Sioli , 26.x.1948 ; 2♀ , ZSM 407 /3, Pará , high Rio Cupari , Flechal , about 150 km from Santarém, Laguinho Silvestre, coll. R. Braun , 29.xii.1947 ; 2♂ , 2♀ , ZSM 407 /4, Pará , Fordlândia , Igarapé Arraia , among submerse leaflitter and tree branches, coll. H. Sioli , 5.vii.1950 ; 1♂ , ZSM 407 /5, Amazonas , left bank of Rio Negro , between Rio Demini and Rio Branco , small creek above Igarapé Adujá , coll. E.J. Fittkau , 13.ii.1962 ; 1♀ , ZSM 407 /6, Amazonas , left bank of Rio Solimões , Santo Antônio do Içá , igarapé, among submerse tree branches, coll. Sattler & H. Sioli , 12.x.1959 ; 1♀ , ZSM 407 /7, Pará , between Rio Arapiuns and Rio Tapajós, Igarapé Mentai , Lago da Boca , among aquatic vegetation, coll. H. Sioli , 13.xi.1952 ; 2♂ , ZSM 407 /8, Pará , high Rio Tapajós , Missão do Cururu , left bank of Rio Cururu , near the confluence of Rio Juruena and Rio São Manuel, igarapé, coll. H. Sioli , 11.v.1942 ; 1♀ , ZSM 407 / 9, Pará , Barra do São Manuel , right bank of Rio São Manuel , near the confluence of Rio Juruena , Igarapé Anipiri , coll. H. Sioli , 21.iv.1941 ; 2♂ , 4♀ , ZSM 407 /10, Amazonas , left bank of Rio Negro , near the mouth of Rio Içana , Igarapé Caburís , coll. H. Sioli , 24.viii.1952 ; 1♂ , ZSM 407 /11, Amazonas , left bank of Rio Negro , near the mouth of Rio Içana , about 60 km north-weast from Uaupés (currently São Gabriel da Cachoeira ), Igarapé Iaitíua , among submerse leaflitter and tree branches, coll. H. Sioli , 24.ix.1952 ; 1♀ , ZSM 407 /12, Pará , Mulata , about 110 km northeast from Santarém , left bank of Rio Amazonas , Igarapé do Açaizal , puddle among acai trees ( Euterpe oboracea ), coll. H. Sioli , 23.ix.1954 ; 1♂ , 1♀ , ZSM 407 /13, Amazonas , outskirts of Manaus , Ponta Negra , Igarapé do Gigante , coll. E.J. Fittkau , 04.vii.1961 ; 1♀ , 1♀ ov, ZSM 407 /14, Amazonas , between Rio Negro and Rio Solimões , in front of Manaus, Lago Janauarí, coll. U. Irmler , 24.v.1971 – 19.iii.1972 ; 1♂ , ZSM 407/15 , Pará , Belterra , about 30 km south-west from Santarém , right bank of Rio Tapajós, mouth of Igarapé Grande, Lago Jruçanga , among aquatic vegetation , coll. R. Braun & H. Sioli , 26.ii–1.xii.1948 ; 1♀ , ZSM 407 /16, Amazonas , Rio Madeira , near Três Casas , about 560 km from the mouth of Rio Madeira , Lago Paxiúba , coll. H. Sioli , 14.xi.1941 ; 1♂ , 2 juveniles , ZSM 407 /17, Amazonas , Rio Amazonas , about 30 km southeast from Manaus , Ilha do Careiro, coll. Antonio , xii.1965 ; 1♀ , ZSM 407 /18, Pará , Santarém , igarapé, coll. Sattler & H. Sioli , 14.i.1960 ; 1♂ , 3♀ , ZSM 407 /19, Amazonas , outskirts of Manaus , Ponta Negra , Igarapé do Gigante , coll. E.J. Fittkau , 23.vi.1961 ; 3♂ , ZSM 407 /20, Amazonas , right bank of Rio Negro , about 30 km upstream from Manaus , Igarapé Castanha , coll. E.J. Fittkau , 22.viii.1969 ; 1♀ , ZSM 407 /21, Amazonas , left bank of Rio Solimões , near the mouth of Rio Içá , coll. Sattler & H. Sioli , 07.x.1959 ; 4♂ , 13♀ , ZSM 407 /22, Amazonas , left bank of Rio Negro , Rio Cuieiras basin, tributary of Igarapé Cachoeira , near Manaus, Igarapé Incarnada, coll. E.J. Fittkau , 24.ix.1962 ; 12♂ , 4♀ , ZSM 407 / 23, Amazonas , Rio Maués-Açu , 2–3 km above Maués , poço II, coll. H. Sioli , 26.i.1941 ; 9♂ , 1♀ , ZSM 407 /24, Amazonas , left bank of Rio Negro , between Rio Demini and Rio Branco, Igapó Curitiaú , in submerged leaflitter, coll. E.J. Fittkau , 06.ii.1962 ; 5♂ (cl 2.6– 2.5 mm ), SMF 7807 , Amazonas , left bank of Rio Negro , between Rio Demini and Rio Branco, Igarapé Adujá , coll. E.J. Fittkau , 10.ii.1962 ; 1♀, RMNH. CRUS .D.24209, Amazonas , right bank of Rio Purus , Tapauá , near the mouth of Rio Ipixuna , about 280 km from the mouth of Rio Purus , coll. Axelrod , x-xi . 1963. Additional material : Peru : 3♂ (cl 5.8– 4.5 mm ), MZUSP 16453 , Loreto , Requena province , Genaro Herrera , Río Ucayali basin, coll. F.C.T. Lima , i.2014 ; 1♂ (cl 6.0 mm), 5♀ (cl 5.1– 4.6 mm ), INPA 732 , Loreto , Requena province , Bagazan district, Genaro Herrera, Quebrada Sapuenillo , coll. Olga O. Collart , 28.viii.1986 ; 26♂ (cl 7.4– 4.2 mm ), 20♀ (cl 6.1– 4.1 mm ), 6♀ ov (cl 6.2– 5.9 mm ), INPA 812 , Loreto , Maynas province , Iquitos , Lago Urocococha , 03°43'49''S 73°15'00''W , coll. Carmen García , 10.i.1999 ; 1♂ (cl 6.8 mm ), 1♀ (cl 5.9 mm ), 1♀ ov (cl 6.0 mm), OUMNH .ZC. 2006-21 -0003, Peruvian Amazon , coll. unknown. Venezuela : 9♂ (cl 8.4–5.0 mm), 4♀ (cl 6.1– 3.9 mm ), 1♀ ov (cl 5.9 mm ), USNM 221874 , Amazonas , tributary of Río Mavaca , collector and date unknown ; 15♂ (cl 3.6– 2.9 mm ), 14♀ (cl 3.7– 2.4 mm ), OUMNH .ZC.2010-04-0016, Amazonas , small tributary near Autana , small puddles, coll. O. Helke & J. Tomas , 18.ii.2010 ; 5♂ (cl 3.8– 2.2 mm ), 8♀ (cl 3.5– 2.2 mm ), OUMNH .ZC.2013-05-0046, Amazonas , South of Puerto Ayacucho , Río Autana , coll. O. Helke & J. Tomas , 2010 . Brazil : 3♂ (cl 6.5– 4.6 mm ), 3♀ (cl 5.7– 4.5 mm ), MZUSP 21431 , Amapá , near Porto Grande, Igarapé Japiina, 00°58'375''N 51°36'509''W, in submerged leaflitter, coll. unknown, 27.x.2009 ; 1♂ (cl 4.2 mm ), 2♀ (cl 4.9, 3.1 mm ), MZUSP 21432 , Amapá , near Porto Grande , tributary of Rio Araguari , 00°57'730''N 51°38'600''W, in submerged leaflitter, coll. unknown, 28.x.2009 ; 2♂ (cl 5.9, 3.7 mm ), 2♀ (cl 5.4, 5.2 mm ), MZUSP 21433 , Amapá , near Porto Grande , 00°57'470''N 51°39'080''W, in submerged leaflitter, coll. unknown, 28.x.2009 ; 3♂ (cl 7.0– 5.3 mm ), MZUSP 21434, same collection data as previous lot; 2♀ ov (cl 5.5, 5.3 mm ), MZUSP 22713 , Amapá , Macapá city, igarapé, coll. J. Cunha , 06.iii.2005 ; 1♂ (cl 6.2 mm ), MZUSP 22769 , Amapá , Laranjal do Jari , left bank of Rio Jari , 500 m upstream from Cachoeira de Santo Antônio , 00°37'41''S 52°30'31''W , coll. M. Carvalho , A . Akama, C. Oliveira, F. Marques, 14.x.2007 [fnc. MRC 2007 10 1401]; 11♂ (cl 7.2– 4.2 mm ), 26♀ (cl 5.2– 2.8 mm ), INPA 1081 , Amapá , Rio Araguari , igarapé at Cachoeira da Capivara , in submerged leaflitter, coll. C. Magalhães et al. , 20.viii.1992 ; 1♂ (cl 4.9 mm ), INPA 1214 , Amapá , Serra do Navio , Igarapé Piçarra , coll. V. Py-Daniel et al. , 22.iii.1991 ; 3♂ (cl 5.5– 4.1 mm ), 2♀ (cl 6.0, 5.8 mm ), 1♀ ov (cl 5.8 mm ), MZUSP 6399 , Amazonas , Janauacá , Igarapé São José , coll. J.A.M. Donath , 01.x.1977 ; 2♂ (cl 4.7, 4.5 mm ), 1♀ (cl 6.3 mm ), MZUSP 7297 , Amazonas , near Fonte Boa , igarapé at Jacaré , coll. Epa , 07.x.1968 ; 2♀ (cl 6.0, 5.0 mm), MZUSP 7298, same collection data as previous lot; 4♂ (cl 5.7– 2.8 mm ), 3♀ (cl 3.5– 3.3 mm ), MZUSP 7299 , Amazonas , left bank of Rio Solimões , north of Codajás , Lago Miuá , coll. Epa , 25.ix.1968 ; 3♂ (cl 7.7– 4.2 mm ), 2♀ (cl 6.4, 6.2 mm ), 3♀ ov (cl 6.1– 4.8 mm ), MZUSP 8181 , Amazonas , right bank of Rio Solimões , Lago Janauacá , coll. J. Donath , 09.vi.1978 ; 2♀ (cl 4.9, 4.2 mm ), MZUSP 16331 , Amazonas , Manaus , Tarumã-Mirim , 02°55'S 60°13'W , inside well, in submerged leaflitter, coll. J. Zuanon , 21.x.2004 ; 5♂ (cl 8.1– 4.7 mm ), 2♀ (cl 5.5, 4.6 mm ), 2♀ ov (cl 6.1, 5.7 mm ), MZUSP 16996 , Amazonas , Parque Nacional do Jaú , Igarapé Nazaré , 01°52.6'S 61°35.6'W , coll. A. Kemenes , xi-xii/1998 ; 10♂ (cl 6.4– 3.5 mm ), 13♀ (cl 6.2– 3.6 mm ), 2♀ ov (cl 5.4, 5.3 mm ), MZUSP 16997 , Amazonas , Parque Nacional do Jaú , Igarapé Brito , 01°57.1'S 61°50.2'W , coll. A. Kemenes , xi-xii . 1998; 1♂ (cl 7.5 mm ), MZUSP 20014 , Amazonas , Barcelos , left bank of Rio Negro , igarapé, 00°28.519'S 63°11.495'W , coll. J.B. Mendonça Jr. , 24.x.2008 ; 1♀ (cl 3.1 mm ), MZUSP 20015 , Amazonas , Barcelos , Rio Negro , stomach content of ray, coll. J.B. Mendonça Jr. , 23.x.2008 ; 8♂ (cl 5.8– 3.5 mm ), 5♀ (cl 4.5– 3.2 mm ), MZUSP 22775 , Amazonas , Serra do Mucura , high Rio Tiquié , igarapé, 00°10'N 69°07'W , coll. F.C.T. Lima , 10-11.iii.2006 ; 10♂ (cl 6.5– 4.2 mm ), 9♀ (cl 5.4– 3.8 mm ), 2♀ ov (cl 5.3, 5.0 mm), MZUSP 34175 , Amazonas , tributary of Rio Jufari , Igarapé Santa Fé , 01°00.310'S 62°12.162'W , coll. J.B. Mendonça Jr. , 01.ix.2011 ; 1♀ ov (cl 5.2 mm ), MZUSP 34177 , Amazonas , tributary of Rio Jufari , Igarapé Tubana , 01°04.953'S 62°07.755'W , inside submerged trunk, coll. J.B. Mendonça Jr. , 29.viii.2011 ; 11♂ (cl 5.9– 3.4 mm ), 3♀ (cl 4.8– 4.5 mm ), 8♀ ov (cl 5.0– 4.5 mm ), MZUSP 34519 , Amazonas , tributary of Rio Jufari , Igarapé Santa Fé , 01°00'29.1''S 62°12'20.6''W , inside submerged trunk and leaflitter, coll. J.B. Mendonça Jr. , 06.ix.2011 ; 19♂ (cl 6.3– 2.5 mm ), 9♀ (cl 5.0– 3.1 mm ), 2♀ ov (cl 5.0, 4.7 mm ), MZUSP 34520 , Amazonas , tributary of Rio Jufari , Igarapé Santa Fé , 01°00.310'S 62°12.182'W , coll. J.B. Mendonça Jr. , 01.ix.2011 ; 1♂ (cl 6.9 mm ), MZUSP 34522 , Amazonas , tributary of Rio Jufari , Igarapé Tubana , 01°04.953'S 62°07.755'W , inside submerged trunk, coll. J.B. Mendonça Jr. , 29.viii.2011 ; 2♂ (cl 6.6, 6.0 mm), 1♀ ov (cl 4.9 mm ), MZUSP 34523 , Amazonas , tributary of Rio Jufari , Igarapé Tubana , 01°04.953'S 62°07.755'W , col. J.B. Mendonça Jr .; 42♂ (cl 6.3– 3.2 mm ), 46♀ (cl 5.5– 3.3 mm ), 5♀ ov (cl 6.0– 4.8 mm ), MZUSP 34524 , Amazonas , tributary of Rio Jufari , Igarapé Tubana , 01°04.953'S 62°07.755'W , in submerged leaflitter, coll. J.B. mendonça Jr. , 29.viii.2011 ; 3♂ (cl 6.9– 3.5 mm ), 3♀ (cl 5.0– 4.1 mm ), INPA 127 , Amazonas , Rio Tefé , black water, coll. unknown, 11.iii.1980 ; 4♂ (cl 5.3– 4.1 mm ), 2♀ ov (cl 6.6, 6.4 mm ), INPA 264 , Amazonas , Rio Solimões , central lake on Ilha da Marchantaria , coll. B. Friebe , 19.vi.1985 ; 18♂ (cl 7.1– 4.3 mm ), 23♀ (cl 5.2– 2.7 mm ), 2♀ ov (cl 6.0, 5.4 mm ), INPA 268 , Rio Uatumã basin, Rio Uatumã , Balbina e Miriti waterfalls, in submerged leaflitter, coll. C. Magalhães , 13–15.vii.1985 ; 3♀ (cl 6.1–5.0 mm), 1♀ ov (cl 5.9 mm ), INPA 272 , Amazonas , tributary on right bank of Rio Uatumã , igarapé at Miriti waterfall, coll. C. Magalhães , 14.vii.1985 ; 2♂ (cl 4.2, 3.8 mm ), 3♀ (cl 5.1–5.0 mm), INPA 2164 , Amazonas , Rio Solimões , Codajás Urucuzinho , Lago Urucuri , 03°55'10.80''S 62°02'50.50''W , coll. N. Hamada & J. Nessimian , 15.ix.2003 ; 5♀ (cl 7.0– 5.5 mm ), INPA 2171 , Amazonas , Manaus , Rio Negro , Igarapé do Almofada , coll. O. Collart , 24.ii.1989 ; 1♂ (cl 7.4 mm ), 3♀ (cl 6.9–6.0 mm), INPA 2175 , Amazonas , near Manaus, Igarapé Tarumã-Mirim, in submerged leaflitter, coll. C. Magalhães , 23.vi.1983 ; 1♀ ov (cl 5.0 mm), MNRJ 1083 , Amazonas , Borba , coll. Parko , 01.ii.1944 ; 8♀ (cl 5.6–3.0 mm), 2♀ ov (cl 5.4, 5.1 mm ), SMF 13121, Amazonas , South of Manaus , right bank of Rio Solimões , Lago Janauacá , coll. J. Donath , 09.vi.1978 ; 3♂ (cl 7.1– 3.8 mm ), 7♀ (cl 5.9– 3.7 mm ), SMF 31673, Amazonas , Parque Nacional do Jaú , 01°50.363'S 61°35.702'W , coll. A. Kemenes , xi-xii . 1998; 3♂ (cl 6.7– 4.7 mm ), 1♀ (cl 3.9 mm ), 1♀ ov (cl 4.4 mm ), NHM 1985.428 , Amazonas , left bank of Rio Solimões , Lago Janauacá , coll. J. Donath , 12.viii.1978 ; 1♀ (cl 3.8 mm ), NHM 1988.84 .14 (in part), Amazonas , Igarapé Tarumãzinho , in submerged leaflitter, coll. P.A. Henderson , 24.x.1984 ; 2♂ (cl 5.6, 4.5 mm ), 3♀ (cl 6.3– 3.6 mm ), 1♀ ov (cl 6.0 mm), MZUSP 22765 , Pará , Ilha do Marajó , Cachoeira do Arari , Igarapé Araticum , 00°57'32.4''S 48°56'7.2''W , coll. J.M. Cunha & J. Zuanon , 16.v.2006 ; 3♂ (cl 7.0– 5.3 mm ), MZUSP 34178 , Pará , near Itaituba, Igarapé Cantagalo, tributary of Rio Tapajós , 05°47.55694'S 57°24.11374'W , coll. J.B. Mendonça Jr. , 19.i.2013 ; 5♂ (cl 5.7– 3.8 mm ), 5♀ (cl 6.5– 3.8 mm ), MZUSP 34179 , Pará , Itaituba , Rio Tapajós , near Buburé , lake on Ilha Brasileira , 04°44.01667'S 56°40.04333'W , coll. J.B. Mendonça Jr. , 17.viii.2013 ; 5♂ (cl 5.4– 4.7 mm ), 2♀ (cl 4.4, 3.8 mm ), MZUSP 34180 , Pará , Jacareacanga , near Vila São Martins , lake on the right bank of Rio Tapajós , 06°05.49969'S 57°37.36564'W , coll. J.B. Mendonça Jr. , 20.viii.2013 ; 6♂ (cl 6.6– 4.5 mm ), 3♀ (cl 5.1– 3.6 mm ), MZUSP 34181 , Pará , Itaituba , near Vila de Mamãe-Anã , lake in island of Rio Tapajós , 05°47.02615'S 57°24.14773'W , coll. J.B. Mendonça Jr. , 21.viii.2013 ; 20♂ (cl 6.4– 3.9 mm ), 17♀ (cl 4.8– 3.5 mm ), 3♀ ov (cl 6.9– 5.2 mm ), INPA 265 , Pará , Rio Trombetas basin, tributary of Rio Mapuera , Igarapé Borges , coll. V. Py-Daniel et al. , 27.iv.1985 ; 2♂ (cl 4.2, 4.0 mm), 11♀ (cl 4.7– 2.4 mm ), INPA 337 , Pará , right bank of Rio Trombetas , Lago Tapagem , in submerged leaflitter, coll. C. Magalhães , 11.x.1985 ; 4♂ (cl 5.5– 4.6 mm ), 8♀ (cl 6.0– 5.1 mm ), 3♀ ov (cl 6.1– 5.7 mm ), INPA 1109 , Pará , Santarém , Alter-do-Chão , Lago Jacundá , coll. C. García-Dávila , 16.ii.2000 ; 2♀ (cl 6.4, 6.2 mm ), INPA 1135 , Pará , Santarém , Alter-do-Chão , Lago Verde , coll. C. García-Dávila , 18.ii.2000 ; 4♂ (cl 6.9– 3.9 mm ), 6♀ (cl 5.7– 4.5 mm ), INPA 1151 , Pará , Rio Xingu , Igarapé do Ipixuna , coll. unknown, 22.x.1992 ; 32♂ (cl 7.2– 4.6 mm ), 23♀ (cl 7.0– 4.8 mm ), INPA 1167 , Pará , Rio Xingu , Igarapé do Bom Jardim , coll. unknown, 21.x.1992 ; 55♂ (cl 8.1– 3.6 mm ), 78♀ (cl 7.7– 3.5 mm ), INPA 1172 , Pará , Rio Xingu , Lago do São Sebastião , coll. J. Zuanon , 09.x.1992 ; 23♂ (cl 6.8– 3.6 mm ), 9♀ (cl 5.9– 3.5 mm ), INPA 1173 , Pará , Rio Xingu , Lago do São Sebastião , coll. J. Zuanon , 18.x.1992 ; 69♂ (cl 8.0– 3.8 mm ), 49♀ (cl 6.9–4.0 mm), INPA 1191 , Pará , between Buburé and São Luis do Tapajós , left bank of Rio Tapajós , flood plain, among submerged leaflitter and loose trunks, coll. C. Magalhães & L. Moraes , 22–23.x.1991 ; 1♀ (cl 4.5 mm ), INPA 1198 , Pará , Rio Jamanxim , Ilha da Terra Preta , coll. Raimundo , 20.x.1991 ; 1♀ (cl 4.2 mm ), INPA 1205 , Pará , left bank of Rio Tapajós , near the mouth of Rio Cupari , coll. C. Magalhães & L.R. Py-Daniel , 27.x.1991 ; 3♂ (cl 4.9– 3.9 mm ), 6♀ (cl 3.4– 3.1 mm ), INPA 2166 , Pará , Rio Xingu , Ilha de Babaquara , coll. L.R. Py-Daniel & J. Zuanon , 05.x.1990 ; 1♂ (cl 4.4 mm ), 2♀ (cl 3.4, 2.6 mm ), INPA 2163 , Pará , Rio Trombetas , Lago Caetano , coll. V. Py-Daniel et al. , 09.iii.1986 ; 1♀ (cl 6.5 mm ), MPEG 614 , Pará , Belém , Campus de Pesquisa do Museu Paraense Emílio Goeldi , 01°26'41''S 48°25'34''W , coll. F.R. Pimentel & R.M. dos Santos , 15.xii.1998 ; 2♀ (cl 6.0, 5.6 mm ), MPEG 648 , Pará , Belém , Campus de Pesquisa do Museu Paraense Emílio Goeldi , 01°26'41''S 48°25'34''W , coll. F.R. Pimentel & J.O. Dias , 19.i.2000 ; 1♂ (cl 6.5 mm ), MPEG 711 , Pará , Rio Xingu , Altamira , coll. R.M. Souza & Mansinho , 16.xii.2000 ; 4♂ (cl 8.1– 6.3 mm ), 1♀ (cl 5.8 mm ), MPEG 713 , Pará , Melgaço , Floresta Nacional de Caxiuanã , coll. Equipe Curso de Campo, 08.xi.1999 ; 1♂ (cl 5.7 mm ), MZUSP 22768 , Rondônia , Alto Paraíso , 09°42'S 63°19'W , coll. unknown, 20.x.1984 ; 2♂ (cl 7.0, 6.8 mm ), 2♀ ov (cl 6.0, 5.4 mm ), INPA 2174 , Rondônia , Fortaleza do Abunã , left bank of Rio Abunã , igarapé, coll. J. Zuanon et al. , 05.xi.2003 ; 1♀ (cl 5.6 mm ), MZUSP 34176 , Roraima , tributary of Rio Jufari , Igarapé Caicubi , 01°01.567'S 62°06.059'W , coll. J.B. Mendonça Jr. , ix.2011 ; 1♀ ov (cl 4.9 mm ), MZUSP 34517 , Roraima , tributary of Rio Jufari , Igarapé Caicubi , 01°01.418'S 62°06.277'W , in submerged leaflitter, coll. J.B. Mendonça Jr. , 03.ix.2011 ; 1♀ (cl 4.9 mm ), MZUSP 34518 , Roraima , tributary of Rio Jufari , Igarapé Caicubi , 00°59.264'S 62°06.191'W , in submerged leaflitter, coll. J.B. Mendonça Jr. , 02.ix.2011 ; 5♂ (cl 5.8– 3.8 mm ), 2♀ (cl 5.0, 4.1 mm ), MZUSP 34521 , Roraima , tributary of Rio Jufari , Igarapé Santa Fé , 01°00.571'S 62°06.191'W , coll. J.B. Mendonça Jr. , 06.ix.2011 . Type locality. Ilha do Careiro, 30 km south-east of Manaus, Amazonas ( Brazil ). Distribution. Peru ( Loreto ), Colombia ( Amazonas , Guainía , Vichada ), Venezuela ( Amazonas , Delta Amacuro , Monagas ) and Brazil ( Amapá , Amazonas , Pará , Rondônia , Roraima ) ( Tiefenbacher 1978 ; Kensley & Walker 1982 ; Pereira 1991 ; López & Pereira 1998 ; García-Dávila & Magalhães 2003 ; Vieira 2008 ; Valência & Campos 2010 ; Pimentel & Magalhães 2014 ; Santos et al. 2018 ; present study) ( Fig. 63A ). Redescription. Carapace smooth, non-setose. Branchiostegite finely granulated in large specimens, anterior margin produced beyond infra-orbital angle, branchiostegal groove weakly marked. Pterygostomial region produced anteriorly into acute, triangular tooth. Antennal spine conspicuous, placed at same level than infra-orbital angle, partially obscuring infra-orbital angle. Hepatic and branchiostegal spines absent. Rostrum triangular in dorsal view, depressed dorsally, almost reaching or slightly overreaching distal margin of eyes, with row of few long simple setae along each dorsolateral margin ( Figs. 9A–C , 10A–C , 18A–C ). Fourth thoracic sternite with transversal ridge deepening medially, not produced. Fifth thoracic sternite with transversal ridge produced into broad lobe medially. Sixth and seventh thoracic sternites with transversal ridge incomplete, interrupted medially. Eigth thoracic sternite with transverse ridge complete, median region produced anteriorly, V-shaped ( Figs. 9D–F , 18D–F ). Pleon smooth, non-setose. First to fifth pleurae with postero-ventral margin rounded. Second pleura expanded in both sexes, overlapping both first and third pleurae by almost half width. Third to fifth pleurae with long simple setae on antero-ventral margins. Sixth pleura with postero-ventral margin angular, ventromesial margin with fringe of plumose setae. First to third sternites of males and immature females with median process, third one smallest, sometimes inconspicuous. Fourth to sixth sternites smooth, unarmed. Pre-anal plate smooth, lacking longitudinal carina, distally straight ( Fig. 9G–I ). Telson broad, up to twice as long as wide. Lateral margins of telson nearly straight, parallel, not noticeably tapering towards distolateral angle. Distal region of telson broadly rounded, sometimes varying in length, fringed with numerous long, annulate, plumose setae. Distolateral margins of telson with row of few simple setae of variable length. Distolateral angle of telson with pair of cuspidate setae, mesial seta about twice as long as lateral seta. Dorsal surface of telson with two pairs of cuspidate setae, anterior pair usually placed on proximal third of telson length, posterior pair usually placed on medial third of telson length, inserted more mesially than anterior pair. Lateral margin of telson with few long, simple setae. Anal tubercles absent ( Fig. 11A–C ). FIGURE 19. A–H, Euryrhynchus amazoniensis Tiefenbacher, 1978 : male, Igarapé Tubana, tributary of Rio Jufari, Amazonas, Brazil (MZUSP 34524). (A) Epistome, frontal view; (B) Same, lateral view; (C) Left second maxilliped, ultimate article, outer (frontal) view; (D) Same, detail of distal setae; (E) Left third maxilliped, lateral plate of basis, ventro-lateral view; (F) Same, antepenultimate to ultimate segments, mesial view; (G) Same, setae on ultimate segment, mesial view; (H) Same, setae on penultimate segment, mesial view. Eyes short, not overreaching proximal half of basal article of antennular peduncle. Cornea somewhat kidneyshaped in dorsal view, occupying the entire distal region and most of lateral region of ocular peduncle, basal line weakly marked, ommatidia hexagonal, ocellar spot (“ocellus”) absent. Ocular peduncles nearly immobile, basal articulation reduced, inconspicuous ( Fig. 9A–C , 18C ). Antennular peduncle with stylocerite blunt, not produced distally, with cluster of long, simple setae on distodorsal region. Basal article with distolateral angle produced into sharp tooth, reaching or slightly overreaching distolateral projection of medial article, mesial margin fringed with plumose setae, proximal third with ventromesial sharp spine. Medial article almost as long as wide, fringed with plumose setae on both mesial and lateral margins, distolateral and distomesial angles bluntly produced. Distal article quadrate. Lower antennular flagellum long and uniramous. Upper antennular flagellum divided into two rami fused at base by one article; main ramus similar to lower antennular flagellum; accessory ramus shorter and thicker than other antennular flagella, with 3 to 6 free articles, increasing in number in large specimens, length of articles variable, aesthetascs restricted to distal margin of apical article ( Figs. 9A, C , 10D–G , 18G–I ). FIGURE 20. A–I, Euryrhynchus amazoniensis Tiefenbacher, 1978 : male, Igarapé Tubana, tributary of Rio Jufari, Amazonas, Brazil (MZUSP 34524). (A) Left first pereopod, chela, dorsal (mesial) view; (B) Same, detail of setae, dorsal (mesial) view; (C) Right second pereopod, dorsal (mesial) view; (D) Same, teeth of chela, dorsal (mesial) view; (E) Same, unguis of dactylus, dorso-ventral view; (F) Same, articulation between chela and carpus, dorsal view; (G) Same, mesial view; (H) Same, ventral view; (I) Same, lateral view. Antenna with scaphocerite broad, about 1.5 as long as wide, slightly overreaching antennular peduncle, lamella fringed with plumose setae, lateral margin straight or slightly convex, with sharp distal tooth reaching or slightly overreaching lamella. Carpocerite about 3 times as long as wide, reaching distal third of scaphocerite. Basicerite with sharp distolateral tooth reaching proximal fourth of carpocerite, ventral margin of basicerite produced anteriorly into broad, triangular tooth ( Figs. 9A, C , 10H ). Labrum unarmed, broadly rounded in lateral view, tapering medially into longitudinal ridge. Mandible without palp. Molar process with corneous ridges and rows of short setae distally. Incisor process with 4 corneous teeth ( Figs. 12A–F , 19A, B ). First maxilla with two endites. Basal endite broader than coxal endite, furnished distally with cuspidate and serrulate setae. Coxal endite densely furnished with serrulate setae. Palp bilobed. Upper lobe of palp stout, broadly rounded distally, overreaching lower lobe. Lower lobe of palp straight, not curving ventrally, with long distal seta ( Fig. 12G ). Second maxilla with single endite, distally furnished with numerous simple setae. Endopod small, shorter than endite, large at base. Scaphognathite large, fringed with plumose setae ( Fig. 12H ). First maxilliped with endopod quadrate, inner surface concave, distomesial angle furnished with few long plumose setae, outer surface with triangular projection near distal margin. Endites separated by weak suture, best visible in mesial view, margins furnished with papposerrate setae. Exopod well developed, fringed with long plumose setae. Caridean lobe broad, tipping dorsally, fringed with long plumose setae. Epipod unilobed, similar in size with endopod ( Fig. 12I , J ). Second maxilliped with podobranch on epipod. Exopod well developed, about twice as long as endopod, fringed with long plumose setae. Endopod with 4 free articles. Penultimate article of endopod furnished with serrate setae on dorsal margin. Ultimate article of endopod with fringes of serrate and papposerrate setae ( Figs. 13A , 19C, D ). Third maxilliped pediform. Coxa with broad lateral plate, single arthrobranch present. Basis short, about 1/3 length of antepenultimate article of endopod. Endopod with 3 articles, furnished laterally with long simple setae; antepenultimate article longest, furnished mesially with simple setae; penultimate article about 0.7 times length of antepenultimate article, furnished mesially with rows of serrate setae; ultimate article shortest, about 0.8 times length of penultimate article, furnished mesially with rows of serrate setae. Exopod long, reaching proximal third of penultimate article of endopod, fringed with long plumose setae ( Figs. 13B, C , 19E–H ). First pereopod slender, short, carpus and chela overreaching scaphocerite when fully extended. Merus about twice as long as ischium. Carpus about same length or slightly longer than merus. Chela about 0.7 times length of carpus, distal half furnished ventrally with tufts of long serrulate setae, fingers equal in length with palm, fingertips corneous ( Figs. 13D, E , 20A, B ). Second pereopod stout, long, pair similar in form, equal or subequal in size in both sexes. Articles varying in size with age, usually slender in small individuals and stout in large individuals. Surface of ischium to propodus (sometimes also proximal region of dactylus) finely granulated, more conspicuous in large specimens. Merus fused with ischium, distoventral angles unarmed, smooth. Carpus in adults stout in dorsal view, approximately twice as long as wide, about same length or slightly shorter than palm, distomesial angle with distal spine. Chela with transverse constriction near articulation with carpus, fingers with pair of teeth on proximal half of each cutting edge, teeth varying in shape and size with age, fingertips corneous ( Figs. 14 , 15 , 20C–I ). FIGURE 21. A–D, Euryrhynchus amazoniensis Tiefenbacher, 1978 : male, Igarapé Tubana, tributary of Rio Jufari, Amazonas, Brazil (MZUSP 34524). (A) Right third pereopod, dactylus and distal propodus, lateral view; (B) Left third pereopod, dactylus and distal propodus, mesial view; (C) Right fourth pereopod, dactylus and distal propodus, lateral view; (D) Left fourth pereopod, dactylus and distal propodus, mesial view. FIGURE 22. A–F, Euryrhynchus amazoniensis Tiefenbacher, 1978 : male, Igarapé Tubana, tributary of Rio Jufari, Amazonas, Brazil (MZUSP 34524). (A) Right fifth pereopod, dactylus and propodus, lateral view; (B) Same, setae on ventral margin of propodus, lateral view; (C) Left fifth pereopod, dactylus and propodus, mesial view; (D) Same, distal region of dactylus, mesial view; (E) Same, distal region of propodus, mesial view; (F) Same, detail of ventral cuspidate seta, mesial view. Third pereopod stouter than fourth and fifth pereopods. Merus about 1.5 as long as ischium. Carpus about 0.5 as long as merus. Propodus about 1.7 as long as carpus, ventral margin with 8 to 16 cuspidate setae, some more closely spaced on distal third of propodus, dorsal margin usually without cuspidate setae. Dactylus biunguiculate, at least 0.4 as long as propodus, dorsal margin indented, with single cuspidate seta, placed on mesial side ( Figs. 16A–C , 21A, B ). Fourth pereopod similar to third pereopod, but thinner. Propodus with ventral margin furnished with 8 to 14 cuspidate setae, dorsal margin usually with single dorsomesial cuspidate seta on distal third, distodorsal angle without cuspidate seta. Dactylus dorsal margin indented, with subdistal pair of cuspidate setae ( Figs. 16D–G , 21C, D ). Fifth pereopod similar to fourth pereopod, but longer. Carpus about 0.75 as long as merus. Propodus about 1.4 as long as carpus, ventral margin furnished with 7 to 12 cuspidate setae, distal third with 3 to 7 rows of serrate setae, dorsal margin without cuspidate seta. Dactylus about 0.4 as long as propodus, dorsal margin indented, with subdistal pair of cuspidate setae ( Figs. 16H–J , 22 ). FIGURE 23. A–G, Euryrhynchus amazoniensis Tiefenbacher, 1978 : male, Igarapé Tubana, tributary of Rio Jufari, Amazonas, Brazil (MZUSP 34524). (A) Right second pleopod, ventral view; (B) Same, mesial view; (C) Same, dorsal view; (D) Same, detail of apex, dorsal view; (E) Same, detail of median region, mesial view; (F) Same, detail of appendix interna, ventral view; (G) Same, median row of cuspidate setae, ventral view. Male first pleopod protopodite furnished with short row of cuspidate setae on distomesial margin. Exopod at least twice as long as endopod, fringed with few plumose setae. Endopod furnished with cuspidate setae along distomesial margin, plumose setae absent, appendix interna absent. Second pleopod exopod longer than endopod, fringed with plumose setae. Endopod stout, twisted, modified into gonopod, distal half carinate dorsoventrally, tapering into triangular apex, mesial region with 3 rows of cuspidate setae, median row longer than ventral row, almost reaching distal third of endopod, dorsal row continuing on lateral margin of dorsal carina, setae curve irregularly as row approaches apex of endopod, blocking exopod mesially, mesial margin of dorsal carina with triangular lobe, appendix interna reduced, appendix masculina absent. Third to fifth pleopods protopodites furnished with few long setae on lateral margin. Endopod shorter than exopod, both fringed with plumose setae, appendix interna absent ( Figs. 17A–H , 23 ). Female first and second pleopod endopods shorter than exopods, margins smooth or fringed with fewer plumose setae than exopod, appendix interna absent. Third to fifth pleopod protopodites furnished with few long setae on lateral margins. Endopods shorter than exopods, both fringed with plumose setae, appendix interna absent ( Fig. 17I –M ). Uropod broad. Protopodite with well-developed lateral process, at least twice as long as mesial process, curving mesially, furnished distodorsally with transverse row of long simple setae, distomesial angle rounded or angular. Endopod narrower than exopod, fringed with long, annulate, plumose setae, distolateral margin with few long simple setae. Exopod fringed with long, annulate, plumose setae, distal margin somewhat truncated, straight, with cluster of few long simple setae on distolateral margin, diaeresis incomplete, with 5 to 13 cuspidate setae, growing in size towards mesial margin, increasing in number with age ( Fig. 11D–G ). Remarks. Euryrhynchus amazoniensis resembles E . wrzesniowskii , E. taruman sp. nov. and E. tuyuca sp. nov. in having (i) the second pereopod merus with distoventral angles unarmed, smooth ( Fig. 14C ), (ii) the third pereopod dactylus with 1 cuspidate seta on the dorsal margin, placed on mesial side ( Fig. 16B ), and (iii) the fourth pereopod propodus usually without cuspidate seta on the distodorsal angle ( Fig. 16E, F ). However, E . amazoniensis can be readily recognized as the pterygostomial region of carapace is produced anteriorly into a sharp tooth ( Figs. 9C , 10A–C ). Additional morphological differences between E. amazoniensis and the two new species are discussed further below. Euryrhynchus amazoniensis differs from E. wrzesniowskii in several key characters, including (i) the second pereopod carpus with a distal spine on the distomesial angle ( Fig. 14C ) (versus second pereopod carpus with distomesial angle unarmed, smooth in E. wrzesniowskii , Fig. 57D ), (ii) the fifth pereopod of dactylus with a pair of cuspidate setae on the dorsal margin ( Fig. 16I ) (versus fifth pereopod dactylus with 1 cuspidate seta, placed on lateral side in E. wrzesniowskii , Fig. 59G, H ), and (iii) the male gonopod stout, twisted, not overreaching the exopod, and the appendix interna inconspicuous ( Figs. 17B–E , 23 ) (versus male gonopod elongated, straight, overreaching exopod, and appendix interna conspicuous in E. wrzesniowskii , Figs. 60B, C, L , 61 ). Euryrhynchus amazoniensis is easily separated from E. burchelli , E. pemoni , and E. tomasi on the account of the latter three species having: (i) the second pereopod merus with 1 or 2 spines on the distoventral angles ( Figs. 25D ; 34C, 46D), (ii) the third pereopod dactylus with a pair of cuspidate setae on the dorsal margin ( Figs. 27B , 35B , 47B ), and (iii) the fourth pereopod propodus usually with 1 cuspidate seta on the distodorsal angle ( Figs. 27D , 35E , 47D ). The type series from Tiefenbacher (1978) consists of specimens from various localities in the states of Amazonas and Pará (Brazil), most of them collected during the studies of H. Sioli and E.J. Fittkau between the 1950’s and 1970’s (see Sioli 1953 , 1954 , 1955 , 1963 ; Fittkau 1974 ). The type series also includes Holthuis’ (1966) and Irmler’s (1975) material from Amazonas (Brazil) previously reported as E. burchelli . Most specimens from the type series were examined during the present study, except for one lot deposited in Frankfurt (SMF) and four lots deposited in Belgium (Institut Royal des Sciences Naturelles de Belgique, Brussels) (localities 6, 18, 23, 24 and 25 in Tiefenbacher 1978 : 179). Although the geographic range of the type series is large, most type specimens corresponded to E. amazoniensis sensu stricto , whereas only two lots were reidentified as E. taruman sp. nov. (see below). The superficial description provided by Tiefenbacher (1978) may be the cause of several identification errors in subsequent publications involving Brazilian material. For instance, Gomes Corrêa (1980) reported an ovigerous female from Borba (Amazonas, Brazil) (MNRJ 1083) as E. wrzesniowskii , but our analysis revealed that this specimen is actually E. amazoniensis . A number of studies conducted in the Igarapé Tarumã-Mirim (or Tarumãzinho), north-west of Manaus (Amazonas, Brazil), referred to E. amazoniensis (see Walker & Ferreira 1985 ; Magalhães 1988 ; Magalhães & Walker 1988 ; Odinetz Collart & Magalhães 1994 ; Walker 1994 , 2001 ). However, reexamination of lots from this locality, including the voucher specimens from Magalhães (1988) and Magalhães & Walker (1988) (INPA 2169, 2175), often confirmed the presence of E. amazoniensis sensu stricto , but also of E. taruman sp. nov. The material of E. amazoniensis reported in Walker & Ferreira (1985) , Odinetz Collart & Magalhães (1994) and Walker (1994 , 2001 ) was not found at the INPA collections, potentially raising questions about the identity of these specimens. Kensley & Walker (1982) reported E. amazoniensis from several localities in the Amazon basin (including the Igarapé Tarumã-Mirim), however only the lot from Rio Tefé (Amazonas, Brazil) (INPA 127) was found at INPA and is herein confirmed as E. amazoniensis sensu stricto . Part of the specimens reported by Kemenes et al. (2010) and Pimentel & Magalhães (2014) from Amazonas and Pará (Brazil) were reexamined in the present study and confirmed as E. amazoniensis sensu stricto . The material of E. amazoniensis reported from Amapá (Brazil) in Vieira (2008) and from several localities in Venezuela and Colombia in Pereira (1991) , López & Pereira (1998) and Valência & Campos (2010) were not examined herein and, consequently, doubt is cast on the identity of the specimens. Finally, E. amazoniensis is reported herein for the first time from Rondônia.