Leptodoras linnelli Eigenmann, 1912

Sabaj, Mark Henry, 2005, Taxonomic assessment of Leptodoras (Siluriformes: Doradidae) with descriptions of three new species, Neotropical Ichthyology 3 (4), pp. 637-678 : 654-662

Leptodoras linnelli Eigenmann, 1912

Figs. 4e , 5a , 14 and 15a,b

Leptodoras linnelli Eigenmann 1912:191 , pl. 17 (fig. 1), pl. 18 (fig. 1) (type locality: Potaro river (Essequibo dr.) at Tumatumari, Mazaruni-Potaro, Guyana).

Diagnosis. Uniquely distinguished among Leptodoras by shape of upper labial extension: very elongate, straight to weakly curved medially, and nearly uniform in width with a bluntly rounded tip vs. moderately elongate and attenuate (in L. praelongus , copei , hasemani ) or moderately to strongly curved and distal portion distinctly expanded with wide lateral flap (in L. acipenserinus , nelsoni , rogersae , cataniai , juruensis , myersi ).

Leptodoras linnelli is further distinguished from all Leptodoras except L. acipenserinus by having an adipose fin that extends anteriorly as a low thin ridge to a point midway between the anterior insertion of the adipose fin and the posterior insertion of the dorsal fin. Leptodoras linnelli is distinguished from L. acipenserinus by a number of characters including a relatively longer predorsal distance (35.5-38.7% SL vs. 31.6-35.6% in acipenserinus ), inner flap of gill opening incomplete (vs. usually complete, nearly reaching cleithral notch in acipenserinus ), lower sum of midlateral plates (74- 81 vs. 77-86 in acipenserinus ), anal-fin shape (tip of longest branched ray falls short of vertical through tip of last branched ray in extended anal fin and is more or less even with vertical through base of last ray; line defined by tips angled anteriorly, forming a 45-90° angle with long axis of body vs. tip of longest branched ray falls well short of base of last branched ray, line defined by tips sharply angled anteriorly, forming a 30-45° angle with long axis of body in acipenserinus ), pectoral-fin spine length (19.9-26.2% of SL vs. 18.6-21.3% in acipenserinus ) and pectoral-fin spine dentation (teeth strongly retrorse along majority of posterior margin, becoming less retrorse distally, size relatively uniform along distal half, last denticulation usually subterminal vs. teeth becoming gradually larger and less retrorse towards tip of spine, last and/or penultimate denticulation nearly perpendicular to long axis of spine, last denticulation terminal, its lateral margin continuous with tip of pectoral spine in acipenserinus ).

Description. Morphometrics summarized in Table 1. Similar in shape to L. hasemani except head very weakly depressed, snout comparatively longer and more acute; caudal peduncle moderately elongate, depressed. Eye large but with weakly developed adipose eyelid.

Mouth subterminal, jaws edentulous in adults and juveniles as small as 50 mm SL. Maxillary barbel long, usually reaching ventromedial extent of gill opening. Secondary maxillary barbels 7-11 (modally 10), flattened, largely overlapping; proximal secondary maxillary barbels with fimbriate anterior margin and smooth posterior margin; distal ones smooth. Upper labial extension rather elongate, straight to weakly curved medially, width nearly uniform, tip bluntly rounded, ventral surface smooth, distal lateral margin weakly expanded and with small fimbriae. Lower labial extension narrow, attenuate, usually finishing even with or slightly beyond upper labial extension; margins smooth, distal tip often with few small papillae or fimbriae. Interlabial membrane of narrow to moderate width (labial extensions parallel or convergent), comparatively thin with few small papillae. Dorsolabial membrane weakly developed, evenly attenuate posteriorly. Two pairs of jaw barbels with scattered elongate papillae; cojoined by basal membrane; outer pair slightly longer than inner pair and shorter than maxillary barbel, cojoined with lower labial extension via narrow membrane. Branchiostegal membrane with moderately expanded fleshy margin overlapping ventral gill opening; fleshy inner flap along cleithrum incomplete, not reaching cleithral notch for pectoral spine insertion. First gill arch with 15-20 weakly developed gill rakers (length about 2-3 times width); accessory lamellae on medial face of arch and continue well onto medial face of gill filaments (present on every second or third filament); each accessory lamella appears as a column of lappets with first one (opposite rakers) enlarged and deflected medially; accessory lamellae absent or only very weakly developed on lateral faces of gill arch and filaments (may appear as one or few small lappets near base of filaments).

Sum of midlateral plates 74-81 (modally 76, Table 3).Anterior midlateral plates moderately deep, covering about half of corresponding body depth; posterior margins of dorsal and ventral wings rounded with many small serrae. Tympanum usually with 3 small ossifications (weak spines) along postotic laterosensory canal; small fixed spine usually visible along posterior margin of neurocranium where postotic laterosensory canal exits supracleithrum. Postcleithral process short, deep and slightly expanded posteriorly. Middorsal groove on nuchal shield usually well-defined. Nuchal foramina present as small lenticular opening partially or wholly replacing suture between anterior nuchal plate and epioccipital. Skin relatively smooth in adults; juveniles with few, very small papillae on snout and upper head not forming distinct ridges.

Dorsal-fin rays I,6; pectoral-fin rays I,9-10 (modally 10); pelvic-fin rays i,6; total anal-fin rays 12-16 (first 4 to 6 unbranched); caudal-fin rays i,8/9,i; dorsal procurrent caudalfin rays 14-19, ventral procurrent caudal-fin rays 13-17. Dorsal-fin spine of moderate length, sturdy, nearly straight (rarely weakly angled) and evenly attenuate with sharp tip; anterior denticulations antrorse, moderately sized and evenly spaced basally, largely absent from distal third; posterior denticulations small, retrorse basally, becoming straight and more spaced distally, present nearly to tip. Pectoral-fin spine sturdy, long, weakly bowed with blunt tip; anterior denticulations antrorse, moderately sized nearly to tip; posterior denticulations strongly retrorse along most of posterior margin, becoming less retrorse distally, moderately sized and relatively uniform along distal half; last denticulation usually subterminal. Pelvic fin of moderate length, rounded. Anal fin triangular, tip of longest branched ray more or less even with vertical through base of last anal fin ray, distal margin nearly straight or very shallowly concave. Caudal fin forked with rounded or weakly pointed lobes.

Coloration in alcohol. Head and body coloration similar to L. hasemani ; weakly countershaded, upper sides somewhat uniform tan or light gray, occasionally darker brown (Brazilian specimens). Wide dusky middorsal stripe evident in some specimens, flanked by lighter areas along upper sides. Melanophores sometimes weakly concentrated in skin between and above dorsal wings of midlateral plates, effecting appearance of faint dusky stripe. Lower sides and ventral surfaces white to cream.

Dorsal, anal and paired fins without distinct markings. Dorsal fin with faint stippling on rays and skin covering insertion; darker stippling concentrated along anterior margin of dorsal spine and around perimeter of locking spine. Pectoral and pelvic fins cream to white with faint stippling on dorsal surfaces. Anal fin cream, hyaline. Caudal fin with parallel pair of dusky stripes as in L. hasemani .

Distribution and habitat. Leptodoras linnelli is known from the upper río Orinoco (ríos Ventuari and Mavaca) and a tributary of the Casiquiare (río Siapa), Venezuela; Atlantic Coast drainages of the Guianas and northern Brazil (e.g., Essequibo, Demerara, Araguari); and the rios Uatumã (Amazonas dr.), Tacutu (Branco dr.) and lower Demini (Negro dr.), Brazil ( Fig. 16 ). The distribution of L. linnelli appears to be restricted to river systems draining the Guiana Shield. Most collections are from whitewater or turbid rivers, often in places with sandy beaches and swift currents (e.g., cataracts).

Type-material examined. Leptodoras linnelli : holotype, FMNH 53561 [ex. CM 1626 a] (153.5 mm), Potaro river (Essequibo dr.), Tumatumari, Guyana, 1908, C.H. Eigenmann et al . Paratypes (33 of 36, 3 missing): Guyana: BMNH 1911.10.31.73-74 [ex. CM 1627 a-e, ex. IU 12022 ] (1 + 1*, 162.2 mm), same data as holotype ; BMNH 1911.10 .31.75 [ex. CM 1627 a-e, ex. IU 12022 , Tumatumari or ex. CM 1629 a, ex. IU 12023 , Crab Falls] (1, 70.9 mm), Potaro river ( Essequibo dr.), Tumatumari or Essequibo river (Atlantic dr.), Crab Falls, 1908, C.H. Eigenmann et al .; CAS 59775 [ex. CM 1627 a-e, ex. IU 12022 ] (5, 52.1-173.5 mm), same data as holotype ; CAS 59776 [ex. CM 1629 a, ex. IU 12023 ] (2, 59.28, 86.45 mm), Essequibo river (Atlantic Dr.), Crab Falls , 1908, C. H. Eigenmann et al .; CAS 59777 [ex. CM 1628 , ex. IU 12024 ] (1, 51.9 mm), Essequibo River (Atlantic Dr.), Rockstone, 1908, C. H. Eigenmann et al .; CAS 121940 [ex. SU 21940 , ex. CM 1627 a-e, ex. IU 12022 ] (1*, 169 mm), same data as holotype ; FMNH 7399 [ex. CM 1627 a- e, ex. IU 12022 ] (1, 168.0 mm) , FMNH 53186 [ex. CM 1627 a-e, ex. IU 12022 ] (12, 48.9-161.0 mm), same data as holotype ; FMNH 53187 [ex. CM 1628 a, ex. IU 12024 ] (1, 145.1 mm), same data as CAS 59777; FMNH 53188 [ex. CM 1630 ] (1, 138.8 mm), Georgetown Market ?, 1908, C. H. Eigenmann et al .; FMNH 53562 [ex. CM 1629 a, ex. IU 12023 ] (1, 69.0 mm), same data as CAS 59776; MCZ 30070 [ex. CM 1629 a, ex. IU 12023 ] (1, 151.9 mm), same data as CAS 59776; MCZ 30071 [ex. CM 1627 a-e, ex. IU 12022 ] (1*, 151.9 mm), same data as holotype ; NMW 46109 [ex. CM 1627 a-e, ex. IU 12022 ] (1, 145.4 mm), same data as holotype ; USNM 66222 ex . CM 1627 a-e, ex . IU 12022 (1*, 144.2 mm), same data as holotype ; ZMA 110690 [ex. CM 1627 a- e, ex. IU 12022 , Tumatumari or ex. CM 1629 a, ex. IU 12023 , Crab Falls] (1), same data as BMNH 1911.10.31.75.

Non-type material. Brazil: Amapá: INPA 20969 (3, 149- 178mm) , MNHN 1998-0168 (1 + 3*, 153-175.6 mm) , rioAraguari ( Atlantic dr.), cachoeira (waterfall) da Capivara, upstream of Porto Grande (51°52’54.5"W, 1°2’43.6"N), 19-22 Aug 1992. Amazonas: INPA ex. 17709 (1, 54 mm), rio Demini (Negro dr.), near mouth of rioAracá, 22 Jun 1993; INPA 17721 (1, 45 mm) , rio Negro (Amazonas dr.), Barcelos , 6 Jul 1994; MNHN 1996- 1122 (1*, 200.6 mm) , rio Pitinga (Uatumã-Amazonas dr.), Cachoeira 40 ilhas, between Balbina and Pitinga reservoirs, about 15 km dowstream of the Pitinga dam, 1994. Roraima: INPA 2002 (11) , rio Tacutu ( Branco dr.), Bonfim, 17 Mar 1988 . Guyana: AMNH 214846 (8) , Demerara, 1934; AMNH 214913 (2) , Demerara, 26 Nov -1 Dec , 1934; ANSP 39734 (1, 135.3 mm) , Rupununi river ( Essequibo dr.), 1911; ANSP 175880 (3 + 1*, 93.3 mm) , isolated stagnant pool/pond ( Essequibo dr.), some 40 min. from main Essequibo river channel (4°32’43"N, 58°35’02"W), 31 Jan 1997, WGS 97-27; ANSP 175881 (3) , Essequibo river ( Atlantic dr.), sandbar ca. 800 m downstream from Essequibo campsite ( Maipuri ) (4°45’43"N, 58°45’52"W), 29 Jan 1997, WGS 97-25; ANSP 175882 (1*, 84.8 mm) , Essequibo river (Atlantic dr.), sandbars in vicinity of Maipuri campsite (4°34’17"N, 58°35’17"W), 2 Feb 1997, WGS 97-31; ANSP 175883 (1*, 94.2 mm) , Essequibo river (Atlantic dr.) , Essequibo campsite (4°45’41"N, 58°45’53"W), 26 Jan 1997, WGS 97-19; ANSP 177270 (8) , Essequibo river ( Atlantic dr.), extensive sandbar 2 km upstream from Paddle Rock campsite (4°42’20"N, 58°42’26"W), 25 Nov 1997, GGW 97-23; ANSP 177271 (3) , Essequibo river (Atlantic dr.), extensive sandbar 500 m downstream from Paddle Rock campsite (4°44’N, 58°43’W), 23 Nov 1997, GGW 97-17; ANSP 179177 (15) , Takutu river (Branco dr.), ca. 2.75 km west of Saint Ignatius (3°21’18"N, 59°49’51"W), 5 Nov 2002; AUM 27943 (8, 50.0- 59.9 mm) , Demerara River ( Atlantic dr.), 5.05 mi SSW Linden, bearing 195° (5°56’N, 58°18’22"W), 17-18 Oct 1998, Guy 98-6; INHS 49099 (9, 47.0- 70.4 mm) , same data asAUM 27943 . Venezuela: Amazonas: AMNH 91373 (1*, 92.7 mm) , río Mavaca ( Orinoco dr.), near base camp at sand beach, 17 Mar 1989, CJF-AMA 89-21; AMNH 91374 (3 + 2*, 88.1-99.6 mm) , río Mavaca ( Orinoco dr.), 30 min. upriver from base camp, at sand beach on right bank, 10 Mar 1989, CJF 89-10; ANSP 180817 (5) , río Ventuari (Orinoco dr.), village of Marueta at landing, 91 km east-northeast of Macuruco , 159 km east-northeast of San Fernando de Atabapo (4°18’51"N, 66°17’32"W), 6 Apr 2004, VEN 04-12; ANSP 180900 (3) , río Manapiare and mouth of río Yutaje ( Ventuari dr.), 14 km northwest of San Juan de Manapiare (5°26’12"N, 66°6’45"W), 13 Apr 2004, VEN 04-25; ANSP 180902 (2) , río Ventuari (Orinoco dr.), raudales Tencua , 56 km east-southeast of San Juan de Manapiare (5°2’59"N, 65°37’38"W), 19 Apr 2004, VEN 04-31; ANSP 180903 (2) , río Siapa (Casiquiare dr.), raudale Gallineta , 142 km east of San Carlos de Río Negro (1°49’N, 65°47’41"W), 17 Mar 2005, VEN 05-31; ANSP 180906 (3) , río Ventuari (Orinoco dr.), beach at village of Moriche , 116 km northeast of Macuruco , 169 km northeast of San Fernando de Atabapo (4°45’N, 66°21’13"W), 7 Apr 2004, VEN 04-15; CAS 159157 [ex. SU 59157 ] (3 + 4*, 97.4-125 mm), río Casiquiare , beach at mouth of Casiquiare at Orinoco bifurcation, 22 Mar 1925; MBUCV-V 19288 (1*, 85.8 mm) , río Mavaca (Orinoco Dr.), playa arenosa, rio arriba de campamento, 8 Mar 1989; MBUCV-V 19404 (1*, 98.8 mm) , same data as AMNH 91373; MBUCV-V 19689 (3*, 84.6-100 mm) , same data asAMNH 91374. Bolivar: MBUCV-V 10210 (1, 93.2 mm) , río Cuyuní ( Essequibo dr.), isla de Jacobo, cerca del raudal de Kinotovaca, 26 Feb 1977; MBUCV-V 16529 (1*, 110.8 mm) , río Cuyuni ( Essequibo dr.), 10 km oeste del km 88, via El Dorado-Luedpa, Ste. Elena de Vairen , 12Apr 1987; MBUCV-V 16602 (1 + 1*, 157 mm) , same data as MBUCV-V 16529 .

Leptodoras acipenserinus ( Günther, 1868) Figs. 5 d-f, 17, 18a,b and 19a

Oxydoras acipenserinus Günther 1868 a: 475 (type locality: Xeberos (= Jeberos ) near río Aipana , small tributary joining río Huallaga near the latter’s confluence with río Marañon (Amazonas dr.), Loreto, Peru.

Diagnosis. Distinguished from all Leptodoras except L. linnelli by having adipose fin extended anteriorly as a low thin ridge of adipose tissue to a point midway between anterior insertion of adipose fin and posterior insertion of dorsal fin. See diagnosis of L. linnelli for characteristics distinguishing it from L. acipenserinus .

Description. Morphometrics summarized in Table 1. Body very elongate and dorsoventrally depressed, ventrally flattened from snout to vent; head also depressed, short relative to body with comparatively long acute snout; dorsal profile of snout shallowly convex from tip to midway between nares; caudal peduncle long, shallow. Eye moderately sized with weakly developed adipose eyelid.

Mouth subterminal, jaws edentulous in adults, small juveniles with few thin acicular teeth near medial symphysis of dentaries. Maxillary barbel long, usually reaching ventromedial extent of gill opening. Secondary maxillary barbels 9-12 (modally 11), flattened, overlapping proximally, separated distally; proximal secondary maxillary barbels with fimbriate anterior margin and smooth posterior margin; distal ones smooth. Oral hood comparatively short overall, not greatly expanded posteriorly. Upper labial extension elongate, somewhat Lshaped, proximal half straight and narrow, distal half moderately to strongly curved medially and distinctly expanded with wide lateral flap bearing small fimbriae, surface smooth. Lower labial extension narrow, attenuate, finishing before upper labial extension. Interlabial membrane narrow (labial extensions convergent), comparatively thin with few small papillae. Dorsolabial membrane weakly developed, evenly attenuate posteriorly. Two pairs of jaw barbels with scattered elongate papillae; cojoined by basal membrane; outer pair slightly longer than inner pair and shorter than maxillary barbel, cojoined with lower labial extension via narrow membrane. Branchiostegal membrane with moderately expanded fleshy margin overlapping ventral gill opening; fleshy inner flap along cleithrum usually complete, nearly reaching cleithral notch. Morphology of first gill arch similar to L. linnelli .

Sum of midlateral plates 77-86 (modally 82, Table 3). Anterior midlateral plates deep, covering at least half of corresponding body depth; posterior margins of dorsal and ventral wings rounded with many small serrae. Tympanum usually with 3 distinct ossifications (simple or dual spines) along postotic laterosensory canal; small fixed spine usually conspicuous along posterior margin of neurocranium where postotic laterosensory canal exits supracleithrum. Postcleithral process rather robust, short and very deep, distal portion dome shaped with straight ventral margin. Middorsal groove on nuchal shield usually well-defined. Subrectangular nuchal foramina present, replacing suture between epioccipital and anterior nuchal plate. Skin often with distinct fleshy papillae on snout and upper head; papillae consolidated to form low pair of ridges on middorsal snout and additional ridges along margins of orbit and middorsal groove on nuchal shield.

Dorsal-fin rays I,6; pectoral-fin rays I,9-11 (modally 10); pelvic-fin rays i,6; total anal-fin rays 14-17 (first 4 or 5 unbranched); caudal-fin rays i,8/9,i; dorsal procurrent caudalfin rays 14-19, ventral procurrent caudal-fin rays 14-19. Dorsal-fin spine of moderate length, comparatively thin, nearly straight, evenly attenuate with sharp tip; anterior denticulations antrorse, rather small and crowded basally, absent from distal tip; posterior denticulations retrorse to straight, weak, rather inconspicuous. Pectoral-fin spine sturdy, relatively short, anterior margin weakly curved, posterior margin straight, tip blunt; anterior denticulations antrorse, moderately sized nearly to tip; posterior denticulations becoming gradually larger and less retrorse towards tip of spine (last and/or penultimate denticulation nearly perpendicular to long axis of spine); last posterior denticulation terminal, its lateral margin continuous with tip of pectoral spine. Pelvic fin of moderate length with straight to weakly rounded distal margin. Anal fin triangular with elongate base; tip of longest branched ray falls well short of vertical through base of last branched ray when fin extended. Caudal fin deeply forked with elongate and pointed lobes.

Coloration in alcohol. Head and body moderately countershaded, upper sides tan or gray-brown, lower sides and undersurfaces white. Wide dusky middorsal stripe usually evident, flanked by lighter areas along upper sides. Melanophores sometimes weakly concentrated in skin between and above dorsal wings of midlateral plates, forming faint dusky stripe.

Dorsal fin with faint stippling on rays, membranes depigmented, clear; darker stippling along anterior margin of dorsal spine and on skin surrounding dorsal-locking spine and along fin insertion. Pectoral fin with faint stippling on anterior rays and membranes, posterior rays and membranes depigmented, melanophores most concentrated on skin between posterior denticulations of pectoral spine. Pelvic fins with faint stippling on dorsal surfaces. Anal fin cream, hyaline. Elongate preadipose ridge light (depigmented) and often well contrasted with dusky middorsal stripe. Caudal fin with divergent pair of broad diffuse stripes, one on lower half of upper lobe and other on upper half of lower lobe; lower stripe distally expanded along margin of ventral-most rays and membranes.

Coloration in life. Live specimens from the río Nanay, Peru, are light olive in dorsal half of head and body; basal portions of dorsal and caudal fins also with light olive tinge ( Fig. 19a ).

Distribution and habitat. Leptodoras acipenserinus is known from widely separate sites along the cis-Andean piedmont in the upper Amazon basin in Ecuador, Peru and Brazil ( Fig. 16 ). Most specimens are from upland areas in the upper Napo, Marañon (i.e., Huallaga and Pastaza), Ucayali and upper Madeira (i.e., Guaporé and Madre de Dios) systems. A few specimens have been collected in lowland tributaries of the río Amazonas (i.e., Itaya and Nanay) near Iquitos. Leptodoras acipenserinus has not been found in or near the main channel of the río Amazonas downstream of Iquitos. Most specimens are from whitewaters, however this species inhabits moderately blackwater rivers as well (e.g., río Nanay). In the río Nanay it was collected at night with Leptodoras cf. cataniai over a large sandy beach in swift-flowing water.

Type-material examined. Oxydoras acipenserinus : holotype (unique), BMNH 1867.6 .13.32 (178.0 mm), Xeberos, upper Amazons , E. Bartlett [Xeberos (= Jeberos) is a village in the Peruvian Amazon (Department Loreto) near the río Aipana, a small tributary that joins the río Huallaga near the latter’s confluence with the río Marañon (Amazonas Dr.)] .

Non-type material. Brazil: FMNH 58189 (3, 110.5- 119.5 mm), rio Guaporé (Mamoré-Madeira dr.), Maciel, 23 and 26 Jul 1909 . Ecuador: FMNH 88186 (1, 171.0 mm), FMNH 93040 (1, 171.5 mm), río Bobonaza (Pastaza-Marañon dr.), Montalvo, Aug 1958 ; FMNH 88198 (3, 129.7-157.0 mm), FMNH 92625 (2, 122.0, 136.5 mm), río Bobonaza (Pastaza-Marañon dr.), Morete Bobonaza, Feb 1958 ; FMNH 92385 (2*, 155, 196.5 mm), FMNH 92624 (2, 202.0, 203.0 mm), río Bobonaza (Pastaza-Marañon dr.), Morete Bobonaza, Nov 1958 . Napo: FMNH 97140 (1*, 113.3 mm) río Coca (Napo dr.), 7 km upstream from confluence with Napo (0°24’36"S, 76°59’0"W), 23 Sep 1981 , DJS 81-15; FMNH 97141 (2, 115.0, 116.1 mm), río Napo ( Amazonas dr.), 10.7 km upstream from bridge at Coca in main stream (0°32’36"S, 77°2’54"W), 21 Sep 1981 , DJS 81-11; FMNH 97142 (1, 134.2 mm), río Napo (Amazonas dr.), Pompeya , north shore and tower end of sandy island in center of river (0°26.5', 76°38.2'), 7 Oct 1981 , DJS 81-42; FMNH 97143 (2*, 131.5, 150.9 mm), río Payamino (Napo dr.), 23.3 km upstream from confluence with Napo (0°26.9', 77°6.2'), 20 Sep 1981 , DJS 81-6; FMNH 97144 (1, 167.0 mm) río Napo, río Coca ( Amazonas dr.), cocha off mainstream (0°27’12"S, 76°59’24"W), 26 Sep 1981 , DJS 81-24; FMNH 97145 (1*, 161.0 mm), río Aguarico (Napo dr.), near Destacamento militar Cuyabeno and confluence of Cuyabeno and Aguarico (0°15.6', 75°53.9'), 21 Oct 1983 , DJS 83-47; MCZ 48624 (1*, 141 mm), río Napo (Amazonas dr.), sand bank opposite Coca, 1 Dec 1971 , TRR71:1201B. Peru: Loreto: ANSP 178464 (1 + 1*, 108.1 mm), río Itaya (Amazonas dr.), bridge on Iquitos-Nauta highway, approximately 25 miles south-southwest of Iquitos, 8 Aug 2001 , Peru 2001-03; ANSP 178467 (13 + 3*, 107.5-107.9 mm), río Nanay (Amazonas dr.), Pampa Chica, village 4.54 km west of Iquitos , 2 Aug 2001 , Peru 2001-02. Madre de Dios: ANSP 180550 (1), río Madre de Dios (Madeira dr.) , Isla Rolin, ca. 1 hour by boat downstream from Puerto Maldonado (12°33’50"S, 69°03’01"W), 29 Jul 2004 , TCEP 04-52 ; ANSP 180630 (1), río Tahuamanu (Orton-Madre de Dios dr.), vicinity of San Lorenzo (11°27’46"S, 69°18’23"W), 1 Aug 2004 , TCEP 04-54 ; FMNH 70286 (1*, 169.0 mm), Boca Amigo, 8 Nov 1954 ; CAS 59426 (2, 64.7, 99.5 mm), río Madre de Dios ( Madeira dr.), on east end, north side of island opposite Cuzco-Amazonico lodge, 4 Jun 1983 . Ucayali: USNM 261478 (3, 76.5-86.6 mm), río Aguaytia (Ucayali dr.), Nuevo Requena, 24 Oct 1973 .

Figures

Fig. 4. Variation in oral-hood morphology in Anduzedoras and Leptodoras. a. A. oxyrhynchus,ANSP 160628 (SL 124.6 mm). b. L.praelongus,ANSP162464 (SL 124.9 mm).c.L.copei,ANSP 162461 (SL95.9 mm).d. L.hasemani,ANSP 175889(SL86.7 mm). e. L. linnelli,ANSP 175883 (SL 94 mm). f. L. nelsoni, MCNG 13167 (SL 93 mm). g. L. cataniai,ANSP 161533 (SL 162.5 mm).h. L. juruensis, INHS 39465 (SL 117.4 mm). i. L. myersi,ANSP 112319 (SL 72.6 mm).

Fig. 5. Ventral views of heads in Leptodoras. a. L. linnelli, MBUCV-V 16602 (SL 157 mm). b. L. nelsoni, MBUCV-V 14769 (SL 135.8 mm). c. L. rogersae, USNM 226307 (SL 180 mm). d. L. acipenserinus, FMNH 92385 (SL 155 mm). e. L. acipenserinus, FMNH97140 (SL 113.3 mm).f.L.acipenserinus,ANSP 178467 (SL 107.9 mm). g. L.cataniai,ANSP 161532 (SL 142.6 mm).h. L. cf. cataniaiAmazon form,ANSP 180925 (SL 194 mm). i. L. cf.cataniai Nanay form,ANSP 178438 (SL 164.2 mm).

Fig. 14. Leptodoras linnelli, BMNH 1911.10.31:73-74 (SL 162.2 mm, paratype), Potaro river (Essequibo dr.) Tumatumari, Guyana.

Fig. 15. Juvenile and subadult Leptodoras (Orinoco and Essequibo basins). a. L. linnelli, ANSP 175881 (SL 100.1 mm), Essequibo river, Guyana. b. L. linnelli, MBUCV-V 19689 (SL 100.5 mm), río Mavaca (Orinoco dr.), Amazonas, Venezuela.c. L. rogersae, paratype, MBUCV-V 13372 (SL 128.8 mm), río Orinoco, DeltaAmacuro, Venezuela. d. L. nelsoni, paratype, MBUCV- V 14769 (SL 104.5 mm), ríoApure,Apure, Venezuela.

Fig. 16. Distributions of Leptodoras acipenserinus (solid red circles), L. linnelli (solid green circles), L. nelsoni (open red circles) and L. rogersae (open blue circles) (stars denote type localities).

Fig. 19. Live coloration in Leptodoras. a. L. acipenserinus,ANSP 178467 (SL 108 mm), río Nanay (Amazonas dr.), near Iquitos, Loreto, Peru. b. L. cf. cataniai Nanay form, ANSP 179863 (SL 144 mm), ibid. c. L. myersi, ANSP 181045 (SL 78.6 mm), río Amazonas, near Iquitos, Loreto, Peru.