Euryrhynchus wrzesniowskii Miers, 1878

Pachelle, Paulo P. G. & Tavares, Marcos, 2018, The freshwater shrimp family Euryrhynchidae Holthuis, 1950 (Crustacea: Decapoda: Caridea) revisited, with a taxonomic revision of the genus Euryrhynchus Miers, 1878, Zootaxa 4380 (1) : 78-88

Euryrhynchus wrzesniowskii Miers, 1878

( Figs. 1F , 55–61 , 65B )

Euryrhynchus wrzesniowskii Miers, 1878: 662 , pl. 67, fig. 2–2b.

Euryrhynchus wrzesniowskii — Spandl 1926: 90; Gordon 1935: 327, figs. 13–21; Chace 1943: 35; Holthuis 1948: 1111; 1950a: 2; 1950b: 28; 1951: 5, pl. 1, figs. a–l, pl. 2, figs. a–f; Chace 1954: 324; Holthuis 1955: 76, fig. 50; 1956: 68; 1959: 100, fig. 14; 1966: 9; Powell 1976: 883; Hobbs et al. 1977: 1, appendix 1; Tiefenbacher 1978: 183; Gomes Corrêa 1980: 257, figs. 1–9 [non E. wrzesniowskii sensu Miers, 1878 = E. amazoniensis Tiefenbacher, 1978 ]; Rodríguez 1981: 46; Kensley & Walker 1982: 3, fig. 3c, d; Holthuis 1986: 591; Magalhães 1988: 46, tab. I, figs. 19–26; Magalhães & Walker 1988: 281, tab. I; Ramos-Porto & Coelho 1990: 108; Holthuis 1993: 185, fig. 181; Odinetz Collart & Magalhães 1994: 2460, tab. 2; Pereira & García 1995: 117, tab. 1; Pereira 1997: 3, tab. 6, fig. 1; Ramos-Porto & Coelho 1998: 330; Barros & Pimentel 2001: 20; Melo 2003: 326, figs. 178, 179; Vieira 2003: 57, tabs. 3.1, 3.2, figs. 3.3, 3.4; De Grave 2007: 194; Magalhães & Pereira 2007: 114, tabs. 1–4; Vieira 2008: 67, tab. 5.1; Bracken et al. 2009: 288, tab. 1, fig. 1; Mora-Day et al. 2009: 100; De Grave & Fransen 2011: 309; De Grave & Goulding 2011: 288, tab. 1, fig. 5D; Botello & Alvarez 2013: 775, tab. 1, fig. 2; Kou et al. 2013: 504, tab. 1, figs. 1, 2; Pimentel & Magalhães 2014: 1303, fig. 2; Ashelby et al. 2015: 5, tabs. 1–5, fig. 7a–c; Vogt 2016: 172, fig. 6.1a; Santos et al. 2018: 24, figs. 2F–J, 7.

Euryrhynchus Wrzesniowskii — Calman 1907: 297, fig. 1; Chappuis 1927: 88.

Euryrhynchus wrezniowskii — Gordon 1935: 326 [lap. cal.].

Euryrhynchus wrzeniowskii — Coelho & Ramos-Porto 1985: 408 (tab. I) [lap. cal.].

Euryrhnchus wrzesniowskii — Vieira 2003: 60 [lap. cal.].

Euryrhynchus wrzesniowksii — De Grave 2007: 193 [lap. cal.].

Euryrhynchus wrzensiowski — Santos et al. 2018: figs. 2, 7 [lap. cal.].

Material examined. Holotype: ♂? (pleopods missing) (cl 5.1 mm), NHM 79.21 , French Guiana, Cayenne , in well, coll. A. Wrzesniowsky, date unknown. Additional material: Guyana : 11♂ (cl 4.5– 2.6 mm), 10♀ (cl 4.6–3.0 mm), 1♀ ov (cl 4.9 mm), NHM 1935.5.20.30-41, Upper Cuyuni River, Manicole Swamp , coll. G.S. Carter, 31.vii.1933 ; 15♂ (cl 6.6– 3.7 mm), 14♀ (cl 5.2– 3.2 mm), NHM 1935.5.20.42-53, same collection data as previous specimens; 2♀ (cl 4.3, 3.5 mm), NHM 1935.5 .20.54, Mazaruni River, near Penal Settlement , forest pool, coll. G.S. Carter, 19.v.1933 ; 9♂ (cl 5.4– 2.9 mm), 4♀ (cl 5.0–4.0 mm), USNM 195308 , Mazaruni-Potaro district, Skull Point , temporary pool, coll. W.E. Steiner, 23.xii.1982 ; 6♂ (cl 4.9–3.0 mm), 2♀ ov (cl 4.1, 4.0 mm), MZUSP 26171 , Potaro-Siparuni, tributary of Kuribrong River , 05°23'42''N 59°32'20''W, coll. F.C.T. Lima & P. Bernardo, 29.iii.2011 ; 3♂ (cl 5.0– 3.4 mm), 6♀ (cl 4.5– 4.4 mm), MZUSP 26172 , Potaro-Siparuni, tributary of Kuribrong River , 05°23'48''N 59°32'00''W, coll. F.C.T. Lima et al., 21.iv.2010 ; 6♂ (cl 4.9– 3.5 mm), 2♀ (4.8– 4.2 mm), MZUSP 26173 , Potaro-Siparuni, tributary of Kuribrong River , 05°29'N 59°32'W, coll. F.C.T. Lima et al., 26.iii.2011 ; 15♂ (cl 5.3–3.0 mm), 3♀ (cl 3.7– 2.3 mm), 2♀ ov (cl 4.2, 2.9 mm), MZUSP 26174 , Potaro-Siparuni, tributary of Kuribrong River , 05°20'00''N 59°32'39''W, coll. F.C.T. Lima, T.F. Texeira & T.C.P. Muli, 20.v.2011 ; 1♀ ov (cl 5.3 mm), MZUSP 26175 , Potaro-Siparuni, tributary of Kuribrong River , 05°21'27''N 59°35'22''W, coll. T.F. Teixeira & N.K. Lujan, 23.iii.2011. French Guiana : 3♂ (cl 6.8– 5.9 mm), 3♀ (cl 4.6– 4.3 mm), OUMNH.ZC. 2002-15 -0001, Cayenne, l’Hospital Colonial, in well, coll. unknown, 28.xii.1936; 18♂ (cl 5.8– 3.2 mm), 19♀ (cl 5.0– 2.7 mm), 5♀ ov (cl 5.0– 4.2 mm), OUMNH.ZC. 2006-21 -0001, Cascades Fourgassier , 04°37.369'N 52°18.346'W, coll. O. Helke & J. Tomas, 28.iii.2006. Brazil : 1♂ (cl 3.4 mm), 2♀ (cl 4.9, 2.7 mm), NHM 1985.427 , Amazonas, Rio Uatumã , coll. C. Magalhães, 11.vii.1975 ; 1♂ (cl 3.6 mm), 5♀ (cl 4.1– 2.9 mm), MZUSP 17000 , Amazonas, tributary of Rio Uatumã, Cachoeira Miriti , igarapé, coll. C. Magalhães, 13–14.vii.1985 ; 1♀ (cl 4.0 mm), INPA 254 , Amazonas, tributary of Rio Uatumã, cachoeira do Miriti , igarapé, coll. C. Magalhães, 14.vii.1985 ; 3♂ (cl 5.4– 3.6 mm), 3♀ (cl 5.2– 3.7 mm), 2♀ ov (cl 4.9, 4.0 mm), INPA 2167 , Amazonas, Rio Uatumã , coll. C. Magalhães, no date ; 3♂ (cl 5.2– 4.9 mm), 1♀ (cl 5.0 mm), 3♀ ov (cl 4.7– 4.6 mm), MZUSP 34209 , Pará, Rio Trombetas, Lago Tapagem , coll. Equipe Apoidea, 10.iii.1986 ; 3♂ (cl 5.9– 3.8 mm), 8♀ (cl 3.1–2.0 mm), 3♀ ov (cl 5.2– 4.8 mm), MZUSP 34210 , Pará, Rio Trombetas, Lago Zibeira , coll. Peralta et al., 13.iii.1986 ; 9♂ (cl 6.0–3.0 mm), 8♀ (cl 4.5– 4.1 mm), 15♀ ov (cl 5.4– 4.2 mm), MZUSP 34211 , Pará, Rio Trombetas, Lago Jacaré , coll. V. Py-Daniel et al., 10.iii.1986 ; 1♂ (cl 3.1 mm), INPA 0 98, Pará, road between Santarém and Curuá-Una, Igarapé do Guaraná , coll. I. Vieira et al., 14.xii.1977 ; 4♂ (cl 4.9– 3.1 mm), 1♀ (cl 3.1 mm), INPA 133 , Pará, Curuá-Una , coll. R. Best, i– ii.1981 ; 3♂ (cl 4.5– 3.6 mm), 3♀ (cl 5.0– 3.4 mm), INPA 332 , Pará, Rio Trombetas basin, tributary of Rio Mapuera, Igarapé do Patauá , in submerged leaflitter, coll. C. Magalhães, 09.x.1985 ; 2♀ (cl 3.0, 3.1 mm), INPA 338 , Pará, right bank of Rio Trombetas, Lago Tapagem , in submerged leaflitter, coll. C. Magalhães, 11.x.1985 ; 3♂ (cl 6.1– 4.1 mm), 4♀ (cl 5.1–3.0 mm), INPA 448 , Pará, Rio Mapuera basin, igarapés, coll. V. Py-Daniel et al., 04–09.vi.1986 ; 4♂ (cl 5.5– 3.1 mm), 1♀ (cl 4.2 mm), 1♀ ov (cl 4.0 mm), INPA 1110 , Pará, Santarém, Alter-do-Chão, Lago Jacundá , coll. C.R. García, 16.ii.2000 ; 4♂ (cl 5.2– 3.1 mm), 1♀ (cl 3.8 mm), 4♀ ov (cl 4.1–4.0 mm), INPA 1122 , Pará, Santarém, Alter-do-Chão, Lago Preto , coll. C.R. García, 17.ii.2000 ; 2♂ (cl 5.1, 5.0 mm), 3♀ (cl 5.5– 4.6 mm), 5♀ ov (cl 5.0– 4.8 mm), INPA 1238 , Pará, Rio Trombetas basin, igarapé, coll. E. Ferreira & M. Jegu, 15.iv.1985 ; 3♂ (cl 4.0–3.0 mm), 1♀ ov (cl 4.0 mm), INPA 2165 , Pará, Rio Trombetas basin, tributary of Rio Mapuera, Igarapé Borges , coll. V. Py-Daniel et al., 27.iv.1985 ; 12♂ (cl 5.5–3.0 mm), 14♀ (cl 4.0– 2.4 mm), 2♀ ov (cl 3.9–4.4 mm), INPA 2168 , Pará, Rio Trombetas, Lago Caetano , coll. V. Py-Daniel et al., 09.iii.1986 ; 1♂ (cl 3.1 mm), 7♀ (cl 4.6– 3.9 mm), 5♀ ov (cl 4.5– 3.6 mm), INPA 2172 , Pará, Rio Trombetas, Lago do Macaco , coll. V. Py-Daniel et al., 11.iii.1986 ; 1♂ (cl 5.0 mm), 3♀ (cl 4.5– 2.6 mm), 3♀ ov (cl 4.9– 3.9 mm), INPA 2173 , Pará, Rio Trombetas, Lago Abui , coll. V. Py-Daniel et al., 11.iii.1986 ; 2♂ (cl 5.1, 4.0 mm), 3♀ (cl 5.0–4.0 mm), 9♀ ov (cl 5.2– 4.1 mm), INPA 2176 , Pará, Rio Trombetas, Lago Tapaginha , coll. V. Py-Daniel, 12.iii.1986 ; 2♂ (cl 5.5– 2.9 mm), 2♀ (cl 3.7, 3.6 mm), MPEG 720 , Pará, Melgaço, Floresta Nacional de Caxiuanã, Estação Científica Ferreira Pena (ECFPn), 01°43'3.5''S 51°27'36''W, coll. Equipe Curso de Campo, 07.xi.1999 ; 8♂ (cl 5.8– 2.6 mm), 1♀ (cl 4.7 mm), MPEG 723 , Pará, Melgaço, Floresta Nacional de Caxiuanã, Estação Científica Ferreira Pena (ECFPn), 01°43'3.5''S 51°27'36''W, coll. Equipe Curso de Campo, 06.xi.1999.

Type locality. A well in Cayenne (French Guiana).

Distribution. Guyana (Cuyuni-Mazaruni, Potaro-Siparuni), Suriname (Brokopondo, Marowijne, Para, Sipaliwini), French Guiana (Cayenne) and Brazil (Amapá, Amazonas, Pará, Roraima) (Miers 1877; Gordon 1935; Holthuis 1959; Kensley & Walker 1982; Magalhães 1988; Vieira 2008; Pimentel & Magalhães 2014; Santos et al. 2018; present study) ( Fig. 65B ).

Redescription. Carapace smooth, non-setose. Branchiostegite finely granulated in large specimens, anterior margin produced beyond infra-orbital angle, branchiostegal groove weakly marked. Pterygostomial region rounded or produced anteriorly into blunt, broad 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. 55A–C , 56 ).

Fourth thoracic sternite with transversal ridge produced into broad lobe medially. Fifth thoracic sternite with transversal ridge produced into acute lobe. Sixth and seventh thoracic sternites with transversal ridge incomplete, interrupted medially. Eigth thoracic sternite with transverse ridge complete, median region produced anteriorly, Vshaped ( Fig. 55D, E ).

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.

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. 55F ).

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 ( Figs. 55A–C , 56 ).

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 7 free articles, increasing in number in large specimens, length of articles variable, aesthetascs restricted to distal margin of apical article ( Fig. 55A, C, G ).

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 ( Fig. 55A, C ).

Mouthparts typical for genus. 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 ( Fig. 55H ).

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 ( Fig. 55I ).

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 elongated in dorsal view, approximately 2 to 3 as long as wide, about same length or slightly shorter than palm, distomesial angle unarmed, smooth. Chela with proximal 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. 57 , 58 ).

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 12 to 13 cuspidate setae, 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 ( Fig. 59A, B ).

Fourth pereopod similar to third pereopod, but thinner. Propodus with ventral margin furnished with 10 to 11 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 ( Fig. 59C–E ).

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 10 to 11 cuspidate setae, distal third with 4 to 8 rows of serrate setae, dorsal margin without cuspidate seta. Dactylus about 0.4 as long as propodus, dorsal margin indented, with single subdistal cuspidate seta, placed on lateral side ( Fig. 59F–H ).

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 shorter than endopod, fringed with plumose setae. Endopod elongated, straight, modified into gonopod, apex rounded, dorsomesial region with 3 rows of cuspidate setae, mesial row with longer setae, starting at level with the appendix interna and almost reaching apex of endopod, dorsal rows shorter, restricted to the distal half of endopod, not reaching mesial row distally, blocking exopod mesially, appendix interna developed, appendix masculina absent. Third to fifth pleopods protopodites furnished with few long setae on lateral margin. Endopod much shorter than exopod, both fringed with plumose setae, appendix interna present on all pleopods, reaching or overreaching tip of endopod ( Figs. 60A–F, L , 61 ).

Female first and second pleopod endopods slightly 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 much shorter than exopods, both fringed with plumose setae, appendix interna present on all pleopods, reaching or overreaching tip of endopod ( Fig. 60G–K ).

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 produced into triangular tooth. 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 12 cuspidate setae, growing in size towards mesial margin, increasing in number with age ( Fig. 55J ).

Remarks. Euryrhynchus wrzesniowskii is unique in the genus in having no spines on the second pereopod carpus and merus ( Fig. 57D ), the fifth pereopod dactylus with one cuspidate seta on the dorsal margin, placed on lateral side ( Fig. 59G, H ), and the third to fifth pleopods with endopod much shorter than the exopod, with appendix interna reaching or overreaching the tip of the endopod ( Fig. 60D–F, I–K ). A series of specimens from the Kuribrong River basin in Guyana (MZUSP 26172–26174), including large and small individuals of both sexes, differ from the other specimens of E. wrzesniowskii in the proportions of the second pereopod carpus and propodus. In the Kuribrong specimens, the carpus is stouter in dorsal view, less than twice as long as wide, reaching the distal third of palm length, and, in some individuals, the ventral margin of palm is also swollen ( Fig. 58E–G ). In the absence of additional morphological differences, for the time being we assign the Kuribrong specimens to E. wrzesniowskii and consider the differences in the proportions of the second pereopod carpus and propodus as intraspecific variation.

After being described from a single specimen collected in a well in French Guiana, E. wrzesniowskii was later reported from several specimens collected in Guyana and Suriname (see Miers 1877; Gordon 1935; Holthuis 1950b, 1959). The species was first recorded for Brazil based on a single specimen from Borba, Amazonas (see Gomes Corrêa 1980), being later reported from several localities in Pará, Amazonas, Amapá and Roraima (see Kensley & Walker 1982; Magalhães 1988; Vieira 2008; Pimentel & Magalhães 2014; Santos et al. 2018). However, upon present reexamination the specimen reported in Gomes Corrêa (1980) was actually found to be E. amazoniensis .

Figures

FIGURE 1. Species of Euryrhynchus Miers, 1878, photographed in aquarium (unknown procedence). (A–C) males of E. amazoniensis Tiefenbacher, 1978, sensu lato; (D) ovigerous female of E. amazoniensis sensu lato; (E) male of E. tomasi De Grave, 2007; (F) male of E. wrzesniowskii Miers, 1878. Photographs kindly provided by Chris Lukhaup (A, D, E), Brian Ma (C) and Joachim Tomas (B, F).

FIGURE 55. A–J, Euryrhynchus wrzesniowskii Miers, 1878: male (cl 5.4 mm), temporary pool in Skull Point, Mazaruni- Potaro district, Guyana (USNM 195308). (A) Anterior region of the body, dorsal view; (B) Same, eyes and frontal margin of carapace, setaeomitted; (C) Same, lateral view; (D)Fourth sternite of pereon,median region, ventral view; (E)Fifth sternite of pereon, median region, ventral view; (F) Telson, dorsal view, setae omitted; (G) Right antennule, main and accessory rami, ventral view; (H) Right third maxilliped, lateral view; (I) Right first pereopod, lateral view; (J) Right uropod, exopod and lateral process of protopodite, setae omitted.

FIGURE 56. A–F, Euryrhynchus wrzesniowskii Miers, 1878, variations in the eyes and frontal margin of carapace: (A) male (cl 5.0 mm), Cascades Fourgassier, French Guiana (OUMNH.ZC.2006-21-0001); (B) male (cl 5.3 mm), tributary of Kuribrong River, Potaro-Siparuni, Guyana (MZUSP 26174); (C, D) male (cl 6.0 mm), Lago Jacaré, Rio Trombetas, Pará, Brazil (MZUSP 34211); (E, F) male (cl 6.8 mm), well at l’Hospital Colonial, Cayenne, French Guiana (OUMNH.ZC.2002-15-0001); (G, H) holotype (cl 5.1 mm), well in Cayenne, French Guiana (NHM 79.21).Setae omitted in A–C, E and G.

FIGURE 57. A–E, Euryrhynchus wrzesniowskii Miers, 1878: male (cl 5.4 mm), temporary pool in Skull Point, Mazaruni- Potaro district, Guyana (USNM 195308). (A) Left second pereopod, lateral view; (B) Same, chela and carpus, dorsal (mesial) view; (C) Right second pereopod, lateral view; (D) Same, carpus and distal region of merus, mesial view, setae and granules omitted; (E) Same, chela andcarpus, dorsal (mesial) view.

FIGURE 58. A–G, Euryrhynchus wrzesniowskii Miers, 1878: (A) male (cl 6.0 mm), Lago Jacaré, Rio Trombetas, Pará, Brazil (MZUSP 34211); (B) male (cl 6.8 mm), well at l’Hospital Colonial, Cayenne, French Guiana (OUMNH.ZC.2002-15-0001); (C, D) holotype (cl 5.1 mm), well in Cayenne, French Guiana (NHM 79.21); (E) male (cl 4.6 mm), tributary of Kuribrong River, Potaro-Siparuni, Guyana (MZUSP 26174); (F) male (cl 5.3 mm), same lot as previous specimen; (G) male (cl 4.3 mm), tributary of Kuribrong River, Potaro-Siparuni, Guyana (MZUSP 26173). (A, B) Right second pereopod, chela and carpus, dorsal (mesial) view; (C) Left second pereopod, chela, dorsal (mesial) view, setae and granules omitted; (D) Same, carpus and distal region of merus, mesial view, setae and granules omitted; (E–G) Left second pereopod, chela and carpus, dorsal (mesial) view.

FIGURE 59. A–G, Euryrhynchus wrzesniowskii Miers, 1878: male (cl 5.4 mm), temporary pool in Skull Point, Mazaruni- Potaro district, Guyana (USNM 195308). (A) Right third pereopod, lateral view; (B) Same, dactylus and distal region of propodus, lateral view; (C) Right fourth pereopod, lateral view; (D) Same, dactylus and distal region of propodus, lateral view; (E) Same, mesial view; (F) Right fifth pereopod, lateral view; (G) Same, dactylus and distal region of propodus, lateral view; (H) Same, mesial view.

FIGURE 60. A–L, Euryrhynchus wrzesniowskii Miers, 1878: (A–F) male (cl 5.4 mm) temporary pool in Skull Point, Mazaruni-Potaro district, Guyana (USNM 195308); (G–K) female(cl 5.0 mm), same lot as previous specimen; (L)male (cl 5.3 mm), tributary of Kuribrong River, Potaro-Siparuni, Guyana (MZUSP 26174).(A) Right first pleopod, ventral view; (B) Right second pleopod, ventral view; (C) Same, gonopod (endopod) and exopod, dorsal view; (D) Right third pleopod, ventral view; (E) Right fourth pleopod, ventral view; (F) Right fifth pleopod, ventral view; (G) Right first pleopod, ventral view; (H) Right second pleopod, ventral view; (I) Right third pleopod, ventral view; (J) Right fourth pleopod, ventral view; (K) Right fifth pleopod, ventral view; (L) Right second pleopod, gonopod (endopod) and exopod, dorsal view. Plumose setae omitted.

FIGURE 61. A–F, Euryrhynchus wrzesniowskii Miers, 1878: male, tributary of Kuribrong River, Potaro-Siparuni, Guyana (MZUSP 26174). (A) Right second pleopod, ventral view; (B) Same, mesial view; (C) Same, dorsal view; (D) Same, detail of apex, dorsal view; (E)Same, appendix interna, ventral view; (F) Same, medianrows of cuspidate setae, dorsal view.

FIGURE 65. Distribution maps for the South American euryrhynchids Euryrhynchus tomasi De Grave, 2007 (green circles) and Euryrhynchus tuyuka sp. nov. (blue circle) (A) and Euryrhynchus wrzesniowskii Miers, 1878 (B). The corresponding localities for each point on the maps are indicated on the Appendix 1H–J.