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Pseudoplatystoma orinocoensen. sp.

(Figure 19, Table 4)

Geographic distribution: Orinoco River basin, Venezuela (Fig. 17).

FIGURE 19. Pseudoplatystoma orinocoensen. sp. , holotype, INHS 35880, 489.7 mm SL. Scale 15 cm.

Holotype : INHS 35880 , 489.7 mm SL., near mouth of El Caujavito River, tributary of Orinoco River, southest of Cajarote , 7º41" N , 66º21W , state of Guarico , Venezuela , D. Taphorn et al. , 12 January 1995 .

Paratypes : AMNH 96663 , (1), 59 nautical miles from buoy, small cano emptying into cano Curiapo , 8º36'24"N , 61º00'00"W , Orinoco River , territorio federal delta Amacuro , Venezuela , Eastward et al. , 19 November 1979 . AMNH 96662 , (1), very small primary cano on isla Guacujana south shore , 8º36'N , 60º56'W , territorio federal delta Amacuro , Orinoco basin , Venezuela , Eastward et al. , 19 November 1979 . ANSP 166790 , (1), El Almacen L. Maldonado , 8º6'N , 63º45'50"W , Orinoco River , state of Bolivar , Venezuela , M. Rodriguez , 18 April 1988 . USNM 233830 , (2), small cano on W side of cano Paloma , 8º29'N , 61º25W , Orinoco River , territorio federal delta Amacuro , Venezuela , J. Lundberg , 21 February 1978 .

Material examined: ANSP 166466 , (1), lago Merecure , 8º12'55"N , 63º17'25" , Orinoco River, city of Bolivar , state of Bolivar , Venezuela , M. Rodriguez , 13 April 1988 . ANSP 162391 , (2), Orinoco River, at El Burro , 6º12N , 67º26'W , state of Amazonas , Venezuela , B. Chernoff et al. , 16 November, 1985 . ANSP 166790 , (1), lagoon El Maldonado, Site El Almacen , 8º6'N , 63º45'50"W , Orinoco River , state of Bolivar , Venezuela , M. Rodriguez , 26 April, 1988 . AMNH 77819 , (1), cano Caicara, at bridge on road from Mantecal , 7º22'N , 69º21W , Orinoco River , state of Apure , Venezuela , San Fernando fish station technicians , 24 January 1983 . INHS 29298 , (1), lagoon Curita , 8º9'30"N , 63º35'55" , Orinoco River , state of Anzoategui , Venezuela , M. Rodriguez , 28 May 1987 . INHS 61938 , (1), San Bartolo River at Bartolena ranch, Guarico River , 7º59'20"N , 66º39'W , Orinoco River , state of Guarico , Venezuela , D. C. Taphorn et al. , 24 January 1986 . INHS 34505 , (1), San Bartolo River, Natural Park Aguaro, Guariquito River , 8º4'14"N , 66º40'50"W , Orinoco River , state of Guarico , Venezuela , D. C. Taphorn et al. , 8 January 1995 . INHS 62069 , (1 ds), Guariquito River , 7º54'40"N , 66º33'40"W , Orinoco River , state of Guarico , Venezuela , D. C. Taphorn et al. , 24 January 1986 . INHS 29853 , (1 ds), Apure River, Orinoco River, 2 km N of La Ve , 7º33'95"N , 69º15'48"W , state of Apure , Venezuela , L. M. Page et al. , 23 January 1993 . MCNG 33258 , (1), laguna El Potrero (Las Majadas) , 7º36'40"N , 64º49'50"W , Orinoco River , state of Bolivar , Venezuela , M. Rodriguez , 15 January 1987 . MCNG 1629 , (1 ds), hato El Frio, Apure River , 7º45'S , 67º55'0"W , Orinoco River , state of Apure , Venezuela , D. Taphorn et al. , 10 February 1979 . MCNG 36049 , (1 ds), Sipao River, 6 km up stream from mouth, Orinoco River , district of Sucre, state of Bolivar , Venezuela , D. Rodriguez , 23 March 1997 . MCNG 38851 , (1 ds), Payara River front of mouth of Manglar River, Orinoco River , district of Penalver, state of Apure , Venezuela , D. Arana et al. , 12 December 1997 . UF 80868 , (1), laguna Chiriguare, Orinoco River , state of Portuguesa , Venezuela , D. Taphorn et al. , 3 April 1984 . UF 78077 , (1), 2 km N of San Fernando de Apure, between km markers 305 & 306 , state of Guarico , Orinoco River , Venezuela , Taphorn et al. , 22 March 1981 . UF 80651 , (1), Guasimito River, tributary Guanare River, SE of Arismendi at Chalana site8º20'55"N , 68º2'20"W , Orinoco River , state of Barinas , Venezuela , D. Taphorn et al. , 6 April 1984 . UMMZ 211346 , (2), tidal stream, 49 nautic miles , 8º38'N , 60º50'W , Orinoco River , Venezuela , J. Baskin and D. Stewart , 20 November 1979 . USNM 258157 , (1), Apure River, side channel along dike opposite to municipal slaughter house , 7º35'0N , 67º29'0" , state of Apure , Orinoco River , Venezuela , technicians of Apure fisheries , 25 January 1983 . USNM 260211 , (1), cano W to highway from Calabozo San Fernando, about 35 km south of fundo Masaguaral ( cano Falcon) , 8º14'0"N , 67º35'0W , Orinoco River , state of Guarico , Venezuela , R. P. Vari et al. , 20 January 1983 . USNM 258152 , (1), same as 260211. USNM 258155 , (2), small cano of Apure River , 7º53'0"N , 67º29'0"W , Orinoco River , state of Apure , Venezuela , technicians at Apure Fisheries , 21 January 1983 .

Diagnosis: A species of Pseudoplatystoma ZBK distinguished by a combination of the following features: well defined straight vertical bars along side of body, longer than those of P. fasciatum and P. punctifer ; bars connecting to, or extending to, the dorsal region and continuing onto other side of body; vertical bars of anterior region straight and extending below dorsolateral dusky area; usually no spots below lateral line, some individuals with two or three spots; 39-41 vertebrae.

Description: Maximum recorded length 489.7 mm TL. Body moderately stout, profile of head an acute triangle or pointed toward lips, almost flat anteriorly. Head margins somewhat parallel when viewed dorsally. Mouth rounded with mesethmoid, premaxilla, and lower jaw covered interiorly by thick skin. Viewed dorsally, body widest measurement at pectoral fins, and tapers gradually toward caudal peduncle. Dorsal margin from dorsal fin to adipose fin straight, dorsal margin posterior to adipose fin straight. Ventral margin from mouth to origin of anal fin straight. Posterior surface of head with thin skin leaving almost exposed grooves and roughness on the posterior region of cranium. Median fontanel short and covered by rough and thick skin. Anterior nostrils tubular and whitish, posterior ones with a whitish triangular flap.

Eyes in dorsolateral position, ovoid and located at middle length of head. Maxillary barbels long, reaching origin of pelvic fins, their color blackish dorsally and yellowish ventrally. Chin barbels short in adults, not reaching beyond pectoral fin origin, longer in juveniles (<250 mm), extending beyond tip of pectoral spine. Opercle with pale flap on its margin.

FIGURE 20. Pseudoplatystoma orinocoense , San Bartolo River (Orinoco River) , Venezuela , January 1986 . Photo by Mark H. Sabaj .

Head and rest of body dark dorsal and laterally. Dark pigmentation reaching lateral line. Some individuals pale others yellow ventrally. Vertical bars distributed along side of body. Number of bars greater than in congeners from Guyana ( P. fasciatum ) (about 10 bars) and Amazon ( P. punctifer ) (about 11 bars) and varying between 10 to 14 with an average of 12. Last bar on caudal fin often boomerang-like. Generally, dark bars accompanied by whitish bars. Few individuals with one or two dark loops on posterior region of head. Dorsal fin with few spots on spine and rays. Adipose fin with few spots decreasing in size toward the margin. Pectoral and pelvic fins dark dorsally, pale ventrally. A comparison with other species is presented in Table 9. Color and pattern of adults are shown in Fig. 20.

Etymology: The specific epithet orinocoense refers to the Orinoco River, Venezuela, the drainage in which this species is endemic.

TABLE 4. Descriptive measurements of the body size and shape (in mm), and number of vertebrae for P. orinocoense . Number of individuals measured, 27.

Variables Holotype mean+SD range
Standard length 489.7 300.3+93.5 208.2-524.2
Snout-posterior occipital process 170.3 119.1+32.8 87-207.9
Snout-posterior margin of the opercle 180 116.3+33.4 83.3-202.6
Dorsal fin spine length 61.2 37.1+11.8 22.2-64.7
Pectoral fin spine length 74.9 48.3+14.8 33.5-84.3
Maxillary barbel length 190.7 138.7+36.4 81.7-242.3

...continued

TABLE 4. (continued)

Variables Neotype mean+SD range
Anterior chin barbel length 174.1 121.8+32.8 90-212.6
Insertion maxillary barbel -eye 69.6 45.9+12.9 32.5-80.1
Insertion maxillary barbel -joint pectoral spine 136.5 88.4+25.6 62-154.3
Insertion maxillary barbel -joint dorsal spine 214.9 127.3+38.1 90.5-222.2
Eye -joint pectoral spine 75.1 49.6+15.6 33.3-86.7
Eye -joint dorsal spine 125.4 80.5+23.3 57.3-140.2
Joint pectoral spine -joint dorsal spine 89.1 54.2+15.6 38.5-94.6
Joint pectoral spine -joint first pelvic ray 121.3 70+23.5 44.5-122.2
Joint pectoral spine -joint last ray of dorsal fin 118.3 71.7+21.7 50.6-125.4
Joint dorsal spine -joint first pelvic ray 96.7 54.0+17.9 35.1-94.2
Dorsal fin base length 41.6 26.2+8.0 18-45.6
Joint first pelvic ray -joint last dorsal fin ray 71.3 39.7+12.5 27.4-69.3
Joint first pelvic ray -anal fin origin 124.3 71.8+24.1 47.5-125.9
Joint first pelvic ray -origin adipose fin 131.4 75.1+24.2 57.1-131
Last dorsal fin ray -anal fin origin 136.8 83.7+27.1 57.2-146.3
Last dorsal fin ray -adipose fin origin 109.9 69.2+22.5 47.8-120.8
Anal fin origin -adipose fin origin 60.6 35.4+11.1 24.1-61.9
Anal fin base length 48 32.2+11.6 22.2-68.9
Anal fin origin -adipose fin terminus 61.5 36.5+11.2 25.2-63.8
Adipose fin origin -anal fin terminus 70.7 42.7+12.9 28.5-74.6
Adipose fin length 42.5 26.6+8.0 17.4-46.5
Anal fin terminus -adipose fin terminus 36.8 21.7+6.6 14.6-37.9
Anal fin terminus -ventral caudal fin origin 20.9 11.1+3.7 7.5-20.9
Anal fin terminus -dorsal caudal fin origin 37 21.7+6.9 14.2-37.7
Adipose fin terminus -ventral caudal fin origin 49.9 27.9+9.0 18-48.7
Adipose fin terminus -dorsal caudal fin origin 30.1 17.1+5.7 9.7-30.1
Caudal peduncle depth 31.6 19.4+5.8 13.1-33.7
Number of vertebrae 40 40.07+0.47 39-41

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