Euryrhynchus burchelli Calman, 1907

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) : 38-48

Euryrhynchus burchelli Calman, 1907

( Figs. 24–30 , 63B )

Euryrhynchus Burchelli Calman, 1907: 297 , figs. 2–8.

Euryrhynchus Burchelli — Chappuis 1927: 88.

Euryrhynchus burchelli — Spandl 1926: 90; Gordon 1935: 326; Chace 1943: 35; Holthuis 1950a: 2; Holthuis 1951: 9, pl. 2, figs. g–m; Chace 1954: 324; Holthuis 1956: 68; Holthuis 1966: 6, figs. 2, 3 [= E. amazoniensis Tiefenbacher, 1978 , non E. burchelli Calman, 1907 ]; Irmler 1975: 391 [partim]; Powell 1976: 884; Hobbs et al. 1977: 1, appendix 1; Tiefenbacher 1978: 185, fig. 2c–d; Gomes Corrêa 1980: 258; Rodríguez 1981: 46; Kensley & Walker 1982: 3, fig. 3a–b; Coelho & Ramos-Porto 1985: 407, tab. I; Walker & Ferreira 1985: 266, tab. 1; Holthuis 1986: 591; Magalhães 1988: 41, tab. I, figs. 1–18; Magalhães & Walker 1988: 281, tab. I, figs. 5, 10, 15, 20; Ramos-Porto & Coelho 1990: 108; Odinetz Collart & Magalhães 1994: 2460, tab. 1, 2, fig. 5; Pereira & García 1995: 117, tab. 1; Pereira 1997: 3 (fig. 1), tab. 6; Ramos-Porto & Coelho 1998: 330; Barros & Pimentel 2001: 20; Walker 2001: 565; Melo 2003: 324: figs. 176, 177; Vieira 2003: 60, tabs. 3.1, 3.2, figs. 3.3, 3.4 [?]; De Grave 2007: 193; Magalhães & Pereira 2007: 119, tabs. 1–4; Kemenes et al. 2010: 37; De Grave & Fransen 2011: 309; Vogt 2013: 91; Pimentel & Magalhães 2014: 1302, fig. 2 [partim]; Ashelby et al. 2015: 16; Santos et al. 2018: 24, figs. 2A–E, 6.

Eyryrhynchus burchelli — Santos et al. 2018: figs. 2, 6 [lap. cal.].

Material examined. Holotype: ♂? (heavily damaged, without chelipeds, pereopods, pleopods and telson) (cl 4.8 mm), OUMNH.ZC. 2006-21 -0002, Brazil, Pará, from well , coll. W.J. Burchell, 04.ix.1829. Additional material: Brazil: 1♀ (cl 3.2 mm), MZUSP 32749 , Amapá, Macapá city, igarapé at Mr Marcondes property , coll. J. Cunha, 06.iii.2005; 2♂ (cl 3.5, 3.1 mm), 2♀ (cl 4.3, 3.6 mm), MZUSP 8180 , Amazonas, near Manaus, Igarapé Tarumã- Mirim , coll. C. Magalhães, 23.vi.1983; 3♂ (cl 3.2–3.0 mm), 8♀ (cl 4.1– 3.3 mm), MZUSP 16995 , Amazonas, left bank of Rio Negro , near Manaus, Igarapé Mari-Tarumãzinho , coll. O. Collart, 08.iii.1989; 1♂ (cl 3.5 mm), 2♀ (cl 3.3, 2.8 mm), MZUSP 16998 , Amazonas, left bank of Rio Negro, near Manaus, Lago do Acural-Tarumãzinho , coll. O. Collart, 27.xi.1989; 4♂ (cl 3.5– 3.1 mm), 15♀ (cl 5.0– 2.5 mm), 45♀ ov (cl 4.7– 3.5 mm), MZUSP 16999 , Amazonas, Manaus, Rio Negro, Igarapé Mari-Tarumãzinho , coll. O. Collart, 13.iv.1989; 3♂ (cl 3.7– 2.5 mm), 1♀ (cl 2.5 mm), MZUSP 32748 , Amazonas, Barcelos, Rio Negro , in stomach content of Potamotrygon sp. , coll. J.B. Mendonça Jr., 23.x.2008; 1♂ (cl 4.1 mm), 1♀ (cl 5.2 mm), MZUSP 34203 , Amazonas, Igarapé Santa Fé , 01°00.310'S 62°12.182'W , coll. J.B. Mendonça Jr., 01.ix.2011; 7♂ (cl 4.0– 2.4 mm), 10♀ (cl 5.0– 2.7 mm), 3♀ ov (cl 4.3–4.0 mm), INPA 0 95, Amazonas, near Manaus, Igarapé Tarumã-Mirim, igapó, in submerged leaflitter , coll. C. Magalhães, 23.vi.1983 and 28.ii.1984; 8♀ (cl 4.4– 3.8 mm), 2♀ ov (cl 4.2, 4.1 mm), INPA 0 96, Amazonas, near Manaus, Igarapé Tarumã-Mirim , coll. C. Magalhães, 23.vi.1983; 4♂ (cl 4.0– 2.5 mm), 5♀ (cl 4.3–2.0 mm), INPA 105 , Amazonas, Lower Rio Negro, Caju and Cristalino lakes, in submerged leaflitter , coll. C. Magalhães, 21.i.1983 and 13.iv.1983; 1♀ (cl 4.0 mm), INPA 106 , Amazonas, Rio Negro, Arquipélago Anavilhanas , igapó , coll. M. Goulding, iii.1982; 1♀ (cl 4.4 mm), INPA 205 , Amazonas, right bank of Rio Uatumã, igapó near Igarapé Miriti , in submerged leaflitter , coll. C. Magalhães, 12.vii.1985; 4♂ (cl 3.8– 2.5 mm), 5♀ (cl 3.8– 2.7 mm), SMF 7806 , Pará, Rio Tapajós, Santarém, Igarapé Irurá , 02°25.76'S 54°44.83'W, in submerged vegetation , coll. H. Sioli, 01.xii.1940 – 01.iii.1941; 3♂ (cl 3.2–3.0 mm), 6♀ (cl 4.8–4.0 mm), 3♀ ov (4.1–4.0 mm), MZUSP 16904 , Pará, Salvaterra, Marincoara village , 00°43'45.5''S 48°35'08.5''W, in well, among leaflitter , coll. J.M. Cunha & E. Trajano, 27.xii.2005; 9♂ (cl 5.5– 4.1 mm), 1♀ (cl 4.7 mm), MZUSP 16905 , Pará, Salvaterra, Mr. Silvio Colares property, 00°45'32.2''S 48°31'31.4''W, in well , coll. J.M. Cunha & E. Trajano, 26.xii.2005; 1♂ (cl 3.5 mm), 1♀ (cl 4.1 mm), 4♀ ov (cl 4.2– 3.4 mm), INPA 1108 , Pará, Santarém, Alter-do-Chão, Lago Jacundá , coll. C.R. García, 16.ii.2000; 5♂ (cl 4.3– 2.6 mm), 7♀ (cl 4.3– 2.9 mm), 1♀ ov (cl 3.9 mm), INPA 1123 , Pará, Santarém, Alter-do-Chão, Lago Preto , coll. C.R. García, 17.ii.2000; 1♀ (cl 4.4 mm), INPA 1127 , Pará, Santarém, Alter-do-Chão, Lago Minitiapina , coll. C.R. García, 19.ii.2000; 2♂ (cl 4.1, 3.8 mm), 6♀ (cl 4.1– 3.9 mm), 11♀ ov (cl 3.9– 3.6 mm), INPA 1132 , Pará, Santarém, Alter-do-Chão, Lago Verde , coll. C.R. García, 18.ii.2000; 3♀ (cl 3.3– 3.2 mm), INPA 1136 , same collection data as previous specimens; 2♂ (cl 4.0, 3.6 mm), 2♀ (cl 3.7, 3.5 mm), INPA 1144 , Pará, Santarém, Alterdo-Chão, Lago Iruçanga , coll. C.R. García, 21.ii.2000; 2♂ (cl 2.9, 2.6 mm), 4♀ (cl 4.3– 3.1 mm), 1♀ ov (cl 3.3 mm), INPA 1145 , Pará, Santarém, Alter-do-Chão, Lago Jacaré , coll. C.R. García, 21.ii.2000; 1♀ (cl 3.5 mm), INPA 1148 , Pará, Santarém, Alter-do-Chão, Lago das Mangueiras , coll. C.R. García, 21.ii.2000; 1♂ (cl 3.4 mm), 2♀ (cl 4.5–4.0 mm), INPA 1202 , Pará, left bank of Rio Tapajós, near the mouth of Rio Cupari , coll. C. Magalhães & L.R. Py-Daniel, 27.x.1991; 3♀ (cl 3.4– 2.7 mm), INPA 1203 , Pará, right bank of Rio Tapajós, igarapé near Rio Cupari , coll. C. Magalhães & J. Zuanon, 26.x.1991; 3♂ (cl 4.4– 3.2 mm), 2♀ (cl 4.2– 3.8 mm), 1♀ ov (cl 4.2 mm), MPEG 565 , Pará, Santarém Novo, Igarapé Bacuri , coll. F.R. Pimentel & R.N. Yuki, 26.iv.1998; 6♂ (cl 5.1– 3.7 mm), 1♀ (cl 4.1 mm), MPEG 652 , 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, 24.iii.2000; 3♂ (cl 4.4– 3.5 mm), 2♀ (cl 3.8, 2.6 mm), MPEG 716 , Pará, Altamira , Ilha do Forno , coll. R.M. Souza & Dionisio, 18.xii.2000; 2♂ (cl 3.8, 3.0 mm), 1♀ (cl 4.0 mm), MPEG 721 , Pará, Melgaço, Floresta Nacional de Caxiuanã , coll. Equipe Curso de Campo, 07.xi.1999; 3♂ (cl 4.0– 3.9 mm), 4♀ (cl 3.9– 3.7 mm), MPEG 724 , Pará, Melgaço, Floresta Nacional de Caxiuanã , coll. Equipe Curso de Campo, 06.xi.1999; 1♂ (cl 2.6 mm), MZUSP 34204 , Roraima, Igarapé Pretinho , 00°55.988'S 62°06.511'W, in leaflitter , coll. J.B. Mendonça Jr., 09.ix.2011; 3♀ (cl 4.6–3.0 mm), 4♀ ov (cl 4.6– 3.7 mm), MZUSP 34205 , Roraima, Igarapé Pupunha , 01°00'36.4''S 62°05'19.6''W, in submerged leaflitter and loose trunks , coll. J.B. Mendonça Jr., 05.ix.2011; 2♂ (cl 4.9, 3.9 mm), MZUSP 34206 , Roraima, 1.9 km from Vila de Caicubi , 01°01.538’S 62°05.079’W, temporary pool, in submerged leaflitter , coll. J.B. Mendonça Jr., 11.ix.2011; 53♂ (cl 6.0– 3.6 mm), 37♀ (cl 6.1– 4.2 mm), 48♀ ov (cl 5.8– 4.3 mm), 2 juveniles (cl 2.1, 1.7 mm), MZUSP 34207 , Roraima, Sítio São Bento, left bank of Rio Jufari , 00°59'25.3''S 62°09'50.7''W, temporary pool , coll. J.B. Mendonça Jr., 07.ix.2011; 32♂ (cl 5.6–4.0 mm), 10♀ (cl 5.7– 5.3 mm), 5♀ ov (cl 5.3– 5.2 mm), MZUSP 34208 , Roraima, Vila Caicubi , 01°01'28.5''S 62°05'20.0''W, temporary pool, in submerged leaflitter , coll. J.B. Mendonça Jr., 10.ix.2011; 3♂ (cl 5.6– 4.9 mm), 1♀ov (cl 5.3 mm), OUMNH.ZC.2016-01-027, same collection data as previous lot.

Type locality. A well in Pará ( Brazil).

Distribution. Brazil (Amapá, Amazonas, Pará, Roraima) ( Tiefenbacher 1978; Vieira 2003; Pimentel & Magalhães 2014; Santos et al. 2018; present study) ( Fig. 63B ).

Redescription. Carapace smooth, non-setose. Branchiostegite smooth, non-granulated, anterior margin produced beyond infra-orbital angle, branchiostegal groove weakly marked. Pterygostomial region rounded or angular, not produced anteriorly. 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 ( Fig. 24A–C ).

Fourth thoracic sternite with transversal ridge produced into low, wide lobe medially. 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 ( Fig. 24D, 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 pleura 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. 24F ).

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. 24A–C ).

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 5 free articles, increasing in number in large specimens, length of articles variable, aesthetascs restricted to distal margin of apical article ( Fig. 24A, 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. 24A, 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. 24H ).

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. 24I ).

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 dactylus non-granulated, even in large specimens. Merus fused with ischium, distoventral angles with pair of subdistal spines, one on each angle. Carpus in adults stout in dorsal view, approximately twice as long as wide, reaching distal third of palm, distomesial angle with subdistal spine. Chela with proximal transverse constriction near articulation with carpus, fingers with pair of teeth on proximal half of each cutting edge, proximal tooth of fixed finger indented in large specimens, teeth varying in shape and size with age, fingertips corneous ( Figs. 25 , 26 ).

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 9 to 15 cuspidate setae, dorsal margin usually without cuspidate setae. Dactylus biunguiculate, at least 0.4 as long as propodus, dorsal margin indented, with pair of cuspidate setae ( Fig. 27A, B ).

Fourth pereopod similar to third pereopod, but thinner. Propodus with ventral margin furnished with 9 to 14 cuspidate setae, dorsal margin usually with single dorsomesial cuspidate seta on distal third (sometimes additional cuspidate seta present on medial third), distodorsal angle with cuspidate seta. Dactylus dorsal margin indented, with subdistal pair of cuspidate setae ( Fig. 27C, 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 9 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 ( Fig. 27E, F ).

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 shorter than exopod, both fringed with plumose setae, appendix interna present on all pleopods, not reaching tip of endopod ( Figs. 29A–F , 30 ).

Female first and second pleopod endopods similar in length with 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 present on all pleopods, not reaching tip of endopod ( Fig. 29G–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 11 cuspidate setae, growing in size towards mesial margin, increasing in number with age ( Fig. 24J ).

Remarks. Euryrhynchus burchelli can be easily separated from all species of Euryrhynchus by the armature of the second pereopod (carpus with spine on distomesial angle and merus with pair of spines on distoventral angles) ( Fig. 25D ). It is also the only species in the family without fine granules on the second pereopod ( Figs. 25 , 26 ). Some of the examined specimens presented a series of asymmetrical abnormalities, including the distribution of cuspidate setae on third to fifth pereopods dactyli and propodi, telson and uropodal diaeresis ( Fig. 28A–C, E–J [arrows]), the number of spines on the second pereopod merus ( Fig. 28D ), and a male with a gonopod on the left third pleopod (MZUSP 34207). Holthuis (1966) reported specimens of E. burchelli from Lago Jari (Amazonas, Brazil), which were later correctly reidentified as E. amazoniensis by Tiefenbacher (1978). Euryrhynchus amazoniensis was misinterpreted by Holthuis (1966) as E. burchelli on the account of an acute distoventral projection on the second pereopod merus (cf. Holthuis 1966: 10, fig. 2k). However, that spine differs in shape and position from the one typically found in E. burchelli (cf. Fig. 25D ), thus suggesting that it might represent an aberrant specimen (see examples of aberrant specimens in Fig. 28 ). Although Holthuis’ (1966) material was not examined in the present study, the specimen illustrated by the author indeed presents typical key characters of E. amazoniensis and might well belong to E. amazoniensis . These characters include uropodal protopodite with distomesial angle of lateral process not produced into a tooth (compare Figs. 11E, F , 24J ; Holthuis 1966: fig. 2b), presence of fine granules on the second pereopod (visible on merus of fig. 2k in Holthuis 1966), and armature of carpus and merus of the second pereopod (compare Figs. 14C , 25D ; Holthuis, 1966: fig. 2k).

As currently understood Euryrhynchus burchelli occurs exclusively in the Brazilian Amazon basin ( Fig. 63B ). Coelho & Ramos-Porto (1985: tab 1) listed E. burchelli from both the Paraná basin ( Brazil) and the Guianas, but mentioned no voucher specimens to support their records, as no further material has come to light from these regions, these records are herein considered erroneous. Vieira (2003) reported E. burchelli for the first time from Amapá ( Brazil), but provided no illustrations nor deposited voucher specimens. Taking into account that E. tomasi , a species described a few years later, is also known Amapá ( Fig. 65A , green circles, location 4), reexamination of Vieira's specimens is desirable. It is also worth noting that Euryrhynchus burchelli and E. tomasi are similar to each other, differing mainly in the armature of the second pereopod carpus. Pimentel & Magalhães (2014) also reported three lots of E. burchelli from Amapá (INPA 1082; IEPA 0 0 27, 0050) based upon specimens identified in 2002 (as per the label in the jar of lot INPA 1082). And indeed, reexamination of the lot INPA 1082 revealed that the specimens in this lot actually belong to E. tomasi . Unfortunately, the lots from Amapá (IEPA 0 0 27, 0050) no longer exist in the IEPA collections and thus were not examined.

Figures

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(ZSM406/1).(A) Telson,dorsal view, distalplumose setaeomitted;(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, dorsalview, setaeomitted;(F)Same,lateral process of protopodite,dorsal view,setae omitted; (G) Same, diaeresis of exopod, dorsal view, setaeomitted.

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 24. A–J, Euryrhynchus burchelli Calman, 1907: male (cl 6.0 mm), Sítio São Bento, Roraima, Brazil (MZUSP 34207). (A) Anterior region of the arapace, dorsal view; (B) Same, eyes and frontal margin, dorsal view, setae omitted; (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 thirdmaxilliped, lateral view; (I) Right first pereopod,lateral view;(J) Right uropod,exopodand lateral process of protopodite, dorsal view, setae omitted.

FIGURE25. Euryrhynchus burchelli Calman, 1907:male (cl 6.0 mm), Sítio São Bento, Roraima, Brazil (MZUSP 34207). (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 omitted; (E) Same, chela andcarpus, dorsal (mesial) view.

FIGURE 26. A–E, Euryrhynchus burchelli Calman, 1907: (A) male (cl 5.5 mm), Sítio São Bento, Roraima, Brazil (MZUSP 34207); (B, C) male (cl 4.0 mm) Vila Caicubi, Roraima, Brazil (MZUSP 34208); (D, E) male (cl 4.1 mm) same lot as previous specimen.(A) Left second pereopod, chela and carpus,dorsal (mesial) view; (B) Left second pereopod, lateral view; (C) Same, chela and carpus, dorsal (mesial) view; (D) Left second pereopod, lateral view; (E) Same, chela and carpus, dorsal (mesial) view.

FIGURE 27. A–F, Euryrhynchus burchelli Calman, 1907: male (cl 6.0 mm), Sítio São Bento, Roraima, Brazil (MZUSP 34207).(A) Right third pereopod,lateral view; (B) Same, dactylus anddistal regionof propodus,lateral view; (C) Right fourth pereopod, lateral view; (D) Same, dactylus and distal region of propodus, lateral view; (E) Right fifth pereopod, lateral view; (F) Same, dactylus and distal region of propodus, lateral view.

FIGURE 28. A–J, Euryrhynchus burchelli Calman, 1907, abnormal variations: (A–C, E–J) specimens from Sítio São Bento, Roraima, Brazil (MZUSP 34207) [F and G drawn from the same individual]; (D) male (cl 4.0 mm), Lagos Caju e Cristalino, Amazonas, Brazil (INPA 105). (A) Right fourth pereopod, dactylus and region of propodus, mesial view; (B) Right third pereopod, dactylus, lateral view; (C) Left third pereopod, dactylus and region of propodus, mesial view; (D) Left second pereopod, part of carpus and merus, mesial view; (E) Left third pereopod, dactylus and region of propodus, mesial view; (F) Left uropod, diaeresis, dorsal view;(G) Right uropod, diaeresis, dorsal view; (H) Left fifthpereopod, dactylus, mesial view; (I) Right fourth pereopod, dactylus and region of propodus, mesial view; (J) Telson, dorsal view, setae omitted. Abdormalities are indicated by arrows.

FIGURE 29. A–J, Euryrhynchus burchelli Calman, 1907:(A–F) male (cl 6.0 mm), Sítio São Bento, Roraima, Brazil (MZUSP 34207); (G–K) female (cl 6.0 mm) same lot as previous specimen. (A) Right first pleopod, ventral view; (B) Right second pleopod,ventral view;(C)Same,gonopod (endopod) and exopod, dorsalview; (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. Plumose setae omitted.

FIGURE 30. A–F, Euryrhynchus burchelli Calman, 1907: male, Igarapé Sabure, left bank of Rio Negro, São Gabriel da Cachoeira, Amazonas, Brazil (MZUSP 34201). (A) Right second pleopod, ventral view; (B) Same, dorsal view; (C) Same, mesial view; (D)Same, detail of apex, dorsalview; (E)Same, appendix interna,lateral view;(F)Same,rows of cuspidatesetae, dorsal view.

FIGURE 63. Distribution maps for the South American euryrhynchids Euryrhynchus amazoniensis Tiefenbacher, 1978 (A) and Euryrhynchus burchelli Calman, 1907 (B). The corresponding localities for each point on the maps are indicated on the Appendix 1D, E.

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.