Leptodoras copei ( Fernández-Yépez, 1968 )

Sabaj, Mark Henry, 2005, Taxonomic assessment of Leptodoras (Siluriformes: Doradidae) with descriptions of three new species, Neotropical Ichthyology 3 (4), pp. 637-678 : 649-651

Leptodoras copei ( Fernández-Yépez, 1968) Figs. 4c , 6a and 10

Anduzedoras copei Fernández-Yépez 1968: 31 , fig. 10 (type locality: río Capanaparo , Orinoco dr., Apure, Venezuela).

Diagnosis. Uniquely distinguished among Leptodoras by the following combination: anterior nuchal plate usually wide (laterally expanded) and sharing broad suture with epioccipital, nuchal foramina absent, distal tip of lower labial extension reaching beyond that of upper labial extension, anterior midlateral plates moderately deep (covering a little more than 1/3 of body depth), and pectoral-fin spine short, not reaching anterior origin of pelvic fin when depressed.

Comparisons. Among Leptodoras , only L. hasemani also has a laterally expanded anterior nuchal plate with no nuchal foramina and it is distinguished by having a dark black blotch in distal half of dorsal fin (vs. absent in L. copei ). Leptodoras praelongus also has a long lower labial extension, but is distinguished by having a narrower anterior nuchal plate (supraoccipital usually sharing suture with middle nuchal plate vs. like suture absent in copei ), shallower anterior plates (covering at most 1/4 of body depth vs. 1/ 3 in copei ), and longer pectoral-fin spine (reaching or extending beyond anterior origin of pelvic fin when depressed vs. falling short of pelvic-fin origin in copei ).

Description. Somewhat torpedo-shaped; body elongate, nearly symmetrical in cross-section, predorsal region bluntly cone-shaped, caudal peduncle short, depressed. Eye large with well-developed adipose eyelid.

Mouth subterminal, jaws edentulous in adults and juveniles as small as 31 mm SL. Maxillary barbel of moderate length, finishing short of ventromedial extent of gill opening. Secondary maxillary barbels 7-10 (modally 8), flattened, largely overlapping; proximal secondary maxillary barbels with fimbriate anterior margins; distal ones smooth. Remaining features of buccal hood very similar to L. praelongus except lateral margin of upper labial extension entire or weakly scalloped. Branchiostegal flap and morphology of first gill arch also as in L. praelongus .

Sum of midlateral plates 70-74 (modally 72, Table 3).Anterior midlateral plates of moderate depth, covering slightly more than 1/3 of corresponding body depth; posterior margins of dorsal and ventral wings rounded with small serrae. Tympanum usually with 3 small ossifications (plates or 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 to moderate in length, nearly uniform width or slightly expanded posteriorly. Middorsal groove on nuchal shield weakly defined. Nuchal foramina absent. Skin sometimes with very small fleshy papillae scattered over snout and dorsolateral flanks; papillae on snout variously cojoined to form irregular longitudinal ridges especially in juveniles (<100 mmSL).

Dorsal-fin rays I,6; pectoral-fin rays I,8-9 (modally 9); pelvic-fin rays i,6; total anal-fin rays 13-16 (first 4 or 5 unbranched); caudal-fin rays i,8/9,i; dorsal procurrent caudalfin rays 16-19, ventral procurrent caudal-fin rays 15-17. Dorsal-fin spine of moderate length, slender and weakly curved for much of length with short, sharp divergent tip; anterior denticulations antrorse, very small, crowded basally, largely absent from distal half; posterior denticulations retrorse, small but regularly spaced nearly to tip. Pectoral-fin spine sturdy, short, gently bowed with sharp tip; anterior denticulations antrorse, very small, absent from distal third; posterior denticulations retrorse, gradually decreasing in size from midlength to tip; last posterior denticulation subterminal. Pelvic fin of moderate length, rounded to weakly pointed. Anal fin triangular, tip of longest branched ray more or less even with vertical through base of last ray, distal margin shallowly concave. Caudal fin forked with rounded to weakly pointed lobes.

Coloration in alcohol. Similar to L. praelongus except lower sides more often depigmented. Head and body weakly countershaded, upper sides relatively uniform tan or graybrown, lower and ventral surfaces white to cream. Base of dorsal spine with black anterior margin and dusky sides, remaining dorsal fin usually depigmented except for scattered melanophores on skin covering insertion. Pectoral fin with faint concentration of melanophores along base forming light streaks on distal membranes. Pelvic, anal and paired fins cream, hyaline. Caudal fin with melanophores forming black streaks on lower membranes of upper lobe and upper membranes of lower lobe, remaining fin cream. Juveniles often with two dusky blotches on base of caudal fin, one above and one below midlateral plates (blotches overlie aforementioned streaks).

Specimens from the rio Amazonas (all juveniles, hereafter referred to as Leptodoras cf. copei ) exhibit a color pattern distinguishable from that typical of juvenile L. copei from the rios Negro and Orinoco. In Amazon specimens the base of the dorsal fin is rather darkly pigmented and the dorsolateral sides beneath the dorsal and adipose fins are often dusky with scattered melanophores. In dorsal view, these markings appear as a pair of opposing chevrons.

Distribution and habitat. Leptodoras copei sensu lato is known from the upper río Orinoco, rio Negro and río Amazonas in Venezuela, Brazil and Peru ( Fig. 11 ). Most collections are from large river habitats in the upper río Orinoco, rio Negro and the mouths of their larger tributaries. Leptodoras copei was described on the basis of a juvenile from the río Capanaparo, tributary to the middle Orinoco. Another collection of small juveniles is from a downstream site on the Orinoco near the mouth of the río Caura.

Specimens examined from the rio Amazonas are all juveniles, but may represent (based on color pattern) an undescribed species related to L. copei . Santos et al. (1984:52) figured (as Doras cf. lipophthalmus ) a specimen from the lower rio Tocantins, Brazil (not mapped in Fig. 11 ), that may represent an adult of the Amazon species or yet another undescribed species related to L. copei .

Type-material examined. Anduzedoras copei : holotype, FMNH 84069 [ex. AFY 51.311 ] (65.6 mm), laguna al lado del río Capanaparo (Orinoco dr.), Apure, Venezuela, 22 Mar 1951, A. Fernández-Yépez .

Non-type material. L. copei : Brazil: CAS 158891 [ex. SU 58891 ] (3), rio Negro (Amazonas dr.), Cucuhy (= Cucuí), Colombian bor- der, 14 Feb 1925 . Amazonas: ANSP 180892 (1), rio Negro (Amazonas dr.), 12.6 km downstream from Moura (1°30’47.2"S, 61°32’19.4"W), 7 Dec 1993 , MG-93-033; ANSP 180893 (5), rio Negro (Amazonas dr.), between S. Francisco and S. Francisco de Assis (1°47’20.6"S, 61°24’44.4"W), 6 Dec 1993 , JGL-93-163; ANSP 180896 (1), rio Negro (Amazonas dr.), 3.8 km downstream from S. Francisco, 47.2 km upstream from S. Francisco de Assis (1°41’37"S, 61°26’50"W), 6 Dec 1993 , JPF-93-158. Roraima: ANSP 180894 (2), rio Branco ( Negro dr.), downstream of Atauba and upstream of Caruna (1°17’55"S, 61°51’21"W), 8 Dec 1993 , JGL- 93-174. Venezuela: Amazonas: ANSP 162461 (3, 61.3-95.9 mm), río Orinoco (Atlantic dr.), near mouth of caño Yaguae (3°33’N, 66°47’W), 24 Mar 1987 , V87-47 ; ANSP 162466 (1, 141.46 mm) , MBUCV-V 25616 (1, 129.9 mm), río Orinoco (Atlantic dr.), near mouth of río Iguapo (3°07’N, 65°28’W), 14 Mar 1987 , V87-14 ; CAS 158896 [ex. SU 58896 ] (2), río Orinoco (Atlantic dr.), playa de la boca del Casiquiare, bifurcation, 22 Mar 1925 ; ANSP 180901 (4), río Ventuari (Orinoco dr.), raudales Tencua , 56 km ESE of San Juan de Manapiare (5°2’59"N, 65°37’38"W), 19 Apr 2004 , VEN 04-31 . Bolivar : ANSP 177987 (3, 31- 41 mm), río Orinoco (Atlantic dr.), beaches, canals, lagoons and islands in vicinity of Puerto Las Majadas, near confluence with río Caura (7°38.6’N, 64°50’W), 23 Nov 1985 , V85-54 . L. cf. copei : Brazil: Amazonas: ANSP 180895 (1), rio Solimões ( Amazonas dr.), 62.8 km downstream from Bela Vista, 25 km upstream from Manaus (3°12’08"S, 59°53’42"W), 24 Oct 1993 , JPF-93-011. Para: ANSP 178540 (1, 49.5 mm), rio Amazonas ( Atlantic dr.), 13.6 km downstream from Óbidos, 26.6 km below mouth of rio Trombetas (1°59’58.6"S, 55°25’46.3"W), 27 Oct 1994 , JGL-94-081. Peru: Loreto: ANSP 149948 (1, 49.08 mm) , ANSP 150185 (1, 42.08 mm), río Amazonas (Atlantic dr.), vicinity of Iquitos, between Isla Iquitos and Isla Lapuna, near Lapuna shore, 9 Oct 1955 , P55-9.

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. 6. Lateral (left) and medial (right) views of 1st gill arch.a. Leptodoras copei,ANSP162466 (SL 141.5 mm).b.Leptodoras cataniai,ANSP 161532 (SL 148 mm).

Fig. 10. Leptodoras copei, ANSP 162466 (SL 141.5 mm), río Orinoco (Atlantic dr.), near mouth of río Iguapo, Amazonas, Venezuela.

Fig. 11. Distributions of Leptodoras copei (solid circles, star denotes type locality) and L. cf. copei (open circles).