Corydoras tukano, Britto & Lima, 2003

Britto, Marcelo R. & Lima, Flávio C. T., 2003, Corydoras tukano, a new species of corydoradine catfish from the rio Tiquié, upper rio Negro basin, Brazil (Ostariophysi: Siluriformes: Callichthyidae), Neotropical Ichthyology 1 (2), pp. 83-91 : 84-88

Corydoras tukano , new species

Figs. 1-4

Holotype. MZUSP 82100 (40.9 mm SL), Brazil, estado do Amazonas, rio Tiquié , comunidade de Caruru, beaches in pool below the fall, 0°16’28.9"N, 69°54’53.6"W ( UTM 19 N0398191/ 0030366); Flávio C.T. Lima et al., 20-21 Oct 2002.

Paratypes. All from Brazil, estado do Amazonas: MZUSP 81194 (5, 34.5-40.3 mm SL); CAS 217960 (1, 34.6 mm SL); same data as holotype. MZUSP 64096 (4, 28.2-38.0 mm SL), rio Tiquié, comunidade de Boca do Sal ; Rafael , 23 Oct 2000. MZUSP 65689 (2, 33.2-38.5 mm SL); ANSP 179201 (1, 35.8 mm SL); rio Tiquié , one hour by boat below comunidade de Cunuri, below Cachoeira do Tucano , 0°12’23”N, 69°22’28”W ( UTM 19 N458666/22437; coordinates are from Cunuri); M. L. Lopes, 29 Nov 2000. MZUSP 81179 (2, 34.0- 36.1 mm SL), rio Tiquié ,

do Amazonas, rio Tiquié , comunidade de Caruru .

estado do Amazonas, rio Tiquié, comunidade de Boca do Sal .

comunidade de Boca do Sal, 0°16’22.5” N, 69°54’03” W ( UTM 19N0399757/0030167); N. P. Marques, 25 Oct 2002. MZUSP 81244 (16,20.3-41.4 mmSL) ; INPA 21423 (2,25.6-36.0mmSL) ; MNRJ 25355 (2, 24.4-32.0 mm SL); igarapé Cabari, comunidade de Coração de Maria , 0°16’59.2” N, 69°50’04.2” W ( UTM 19 N0407140/ 0031302); Tarcísio & N. P. Marques, 29 Oct 2002 . MZUSP 81276 (5, 19.9-26.2 mm SL), rio Tiquié, comunidade de Boca do Sal , 0°16’22.5” N, 69°54’03”W ( UTM 19 N0399757/ 0030167); F. C. T. Lima et al., 7 Nov 2002 . MZUSP 81153 (9, 35.4-37.2 mm SL, 6 cs, 20.9-38.3 mm SL), rio Tiquié, between the comunidades de Caruru and Boca de Sal , 0°16’N, 69°54’W; M. L. Lopes et al., 2001-2002 . MZUSP 81216 (2, 17.1-21.3 mm SL), rio Tiquié , between the comunidades de São Domingos Sávio and Jabuti, 0°15-16’N, 69°51-54’W; F.C.T. Lima et al., 7 Nov 2002 .

Diagnosis. Corydoras tukano can be distinguished from all its congeners, except C. reynoldsi Myers & Weitzman and C. weitzmani Nijssen , by its color pattern consisting of a light ground coloration, with three dark, large, roughly rectangular blotches: the first one (“mask”) on the head, across the eye; the second one on the trunk at the level of dorsal fin; and the third one on the trunk at the level of the adipose fin. It can be distinguished from C. reynoldsi by the larger dark blotches, which in C. tukano are broad, with the trunk blotches extending across 5-6 series of lateral plates. In C. reynoldsi , the first trunk blotch (i.e., at the level of dorsal fin), is a discrete, verticallyelongated bar, and the second trunk blotch extends only across 2-3 series of lateral plates (see Myers & Weitzman, 1960: fig. 2; Nijssen & Isbrücker, 1983a: fig.10). See “Discussion” for additional evidence for the recognition of both as distinct species. 86 Corydoras tukano , a new species of corydoradine catfish from upper rio Negro basin

Corydoras tukano may be distinguished from C. weitzmani by the presence of a dark blotch or saddle on the dorsal portion of dorsolateral plates, just posterior to last dorsal-fin ray, that extends from the 9th to the 13th plate (vs. absent); by the second trunk blotch extending vertically from adipose- to anal-fin base and along ventral surface of ventrolateral body plates (vs. reaching neither anal-fin base nor ventral surface of ventrolateral body plates); and by the presence of four dark, vertical stripes, in the caudal fin (vs. stripes absent) (see Nijssen, 1971: fig. 1; Nijssen & Isbrücker, 1986: fig. 27; Burgess, 1989: plate 180).

Description. Morphometric data presented in Table 1. Head compressed with slightly convex dorsal profile; roughly triangular in dorsal view ( Fig. 4 ). Snout rounded. Head profile convex from upper lip to horizontal through the anterior nares; slightly convex from that point to tip of parieto-supraoccipital expansion. Dorsal profile of body slightly convex from tip of parieto-supraoccipital expansion to last dorsal-fin ray. Postdorsal-fin body profile slightly concave to adipose-fin spine; markedly concave from this point to caudal-fin base. Ventral profile of body slightly convex from isthmus to analfin origin. Profile markedly concave from first anal-fin ray to caudal-fin base. Body roughly cylindrical in cross section at pectoral girdle, gradually becoming more compressed toward caudal fin.

Eye round, located dorso-laterally on head; orbit delimited dorsally by frontal and sphenotic, ventrally by infraorbitals. Anterior and posterior nares proximal, only separated by flap of skin. Anterior naris tubular. Posterior naris close to anterodorsal margin of orbit, separated from it by distance equal to naris diameter. Mouth small, subterminal, width nearly equal to bony orbit diameter. Maxillary barbel elongate, usually reaching anteroventral limit of gill opening ( Fig. 4 ). Maxillary barbel slightly longer than outer mental barbel. Inner mental barbel fleshy. Right inner mental barbel forked in one specimen (MZUSP 81194, 38.0 mm SL). Small rounded papillae covering entire surface of all barbels, upper and lower lips, and isthmus. Gill membranes united to isthmus. Four branchiostegal rays covered by thick layer of skin; distal two rays united at their tips by branchiostegal cartilage. Teeth on upper pharyngeal tooth plate 32 (2), 39 (1), 52 (1), 53 (1), or 54 (1), and on fifth ceratobranchial 32 (1), 35 (1), 42 (1), 46 (1), 49 (1), or 50 (1), increasing in number during ontogeny.

Nasal, frontal, sphenotic, compound pterotic, and parietosupraoccipital visible externally, all covered by thin layer of skin and bearing minute scattered odontodes. Frontal fontanel elongate, ellipsoid, covered by thin layer of skin; posterior tip extending into parieto-supraoccipital. Nasal slender, slightly curved laterally, mesial border contacting frontal. Frontal quadrangular; anterior expansion in contact with nasal bone, posterior portion contacting sphenotic and parietosupraoccipital. Sphenotic trapezoid in shape, contacting parieto-supraoccipital dorsally, compound pterotic posteriorly, second infraorbital ventrally. Compound pterotic roughly pipe-shaped, with slender posterior expansion contacting first dorsal body plate and first lateral-line ossicle. Contact region between compound pterotic and first dorsal body plate covered by area of thick skin. Ventral margin of compound pterotic contacting infraorbital 2 and cleithrum. Parietosupraoccipital quadrangular with posterior expansion notched at its tip, sutured with nuchal plate.

Two infraorbital bones, externally visible, covered by thin layer of skin. First infraorbital with slender anterior expansion. Minute odontodes-bearing platelets anterodorsally on orbit ( Fig. 5 ). Presence of small, narrow, roughly triangular platelet between eye and anterior expansion of first infraorbital ( Fig. 5 ). Opercle exposed, compact in shape, with angular free border. Preopercle externally visible, slender and covered by thin layer of skin. Interopercle triangular, covered by thin layer of skin.

Trunk lateral line with two laterosensory canals, reduced to small ossicles. Lateral-line canal entering neurocranium through compound pterotic, splitting into two branches before entering sphenotic: pterotic and preoperculomandibular, each with single pore. Sensory canal continuing through compound pterotic, entering sphenotic as temporal canal, which splits into two branches: one branch giving rise to infraorbital canal, other branch entering frontal through supraorbital canal. Supraorbital canal with two branches: epiphyseal, opening in frontal bone, and anterior, running through nasal bone. Nasal canal with single opening at each end. Infraorbital canal running through entire second infraorbital, extending to infraorbital 1 and opening into two pores. Preoperculomandibular branch giving rise to preoperculomandibular canal, which runs through entire preopercle with three openings, leading to pores 3, 4, and 5, respectively.

Body plates with minute odontodes restricted to posterior margins. Nuchal plate exposed. Cleithrum and mesial process of scapulocoracoid exposed. Minute odontodes scattered over area between scapulocoracoids. Body plates not touching counterparts in specimens up to 28.2 mm SL, leaving narrow naked area on medial dorsal and ventral surfaces. Dorsolateral body plates 23 (11), 24* (21), or 25 (1); ventrolateral body plates 20 (2), 21* (29), or 22 (2); dorsolateral body plates along dorsal-fin base 6 (12), 7* (20), or 8 (1); dorsolateral body plates from adipose fin to caudal-fin base 7 (13) or 8* (20); preadipose platelets 2 (4), 3* (8), 4 (18), or 5 (3). Precaudal vertebrae 8 (3), 9 (3); caudal vertebrae 13 (1), 14 (3), 15 (2); five pairs of ribs, first pair conspicuously larger than others.

Dorsal fin roughly triangular; its origin just posterior to third dorsolateral body plate. Dorsal spine shorter than 1st or 2nd branched rays. Distal tip of spine with minute-segmented unossified portion. Anterior border of dorsal spine smooth; posterior border with minute serrations. First two branched dorsal-fin rays and unossified portion of dorsal spine markedly elongate in large males; first branched ray the longest (see Fig. 3 and “Sexual dimorphism”, below). Dorsal-fin rays I, 7 in all specimens examined. Adipose fin roughly triangular; its origin separated from base of last dorsal-fin ray by 7-9 dorsolateral body plates. Anal fin roughly triangular; its origin located just posterior to 13th to14th ventrolateral body plates, at vertical through anterior margin of adipose-fin spine. Analfin rays ii, 5 in all specimens. Pectoral fin triangular; its origin located just posterior to gill opening. Ossified portion of pectoral spine shorter than first branched rays. Distal tip of spine with minute-segmented unossified portion. Pectoral spine with well-developed serrations along entire posterior border. Pectoral-fin rays I,8, one specimen with I,7. Pelvic fin ellipsoid; its origin just below second ventrolateral body plate, at vertical through base of second branched dorsal-fin ray. Pelvic-fin rays i,5. Caudal fin bilobed; upper lobe slightly longer. Principal caudal-fin rays i,6/6,i, one specimen i,7/6,i; upper procurrent caudal-fin rays iii; lower procurrent caudalfin rays iii. All fins with minute odontodes scattered over all rays.

Color in alcohol. Ground coloration of head gray to brown, light ventrally. Wide, slightly oblique dark vertical blotch (“mask”) from top of head throughout anterior and posterior margins of eye to lower anterior opercle corner. Dark v-shaped stripe between nares, with angle directed anteriorly. Barbels cream. Opercle and preopercle with narrow, dark, oblique, vertically-elongated blotch, formed by relatively large chromatophores.

Ground color of trunk cream to light brown. Nuchal plate gray to dark brown. Large, roughly rectangular, dorsolateral dark blotch (“first trunk blotch”) extending dorsally from posterior margin of second plate to fifth-eighth dorsal plate, and ventrally from posterior margin of cleithrum to fifth ventral plate. Dark blotch on dorsal portion of dorsolateral plates, just posterior to last dorsal-fin ray, extending from 9th to 13th plate; in some specimens connected to large, anterior dorsolateral blotch. Second large, roughly rectangular, dorsolateral dark blotch (“second trunk blotch”) below adipose fin, extending vertically from adipose- to anal-fin base. Scattered chromatophores on margins of plates, close to midline, between the two large dorsolateral blotches. Caudal fin with four vertical, narrow dark stripes. Dorsal- and pectoral-fin spines gray; remaining rays and membrane of both fins unpigmented. Base of anterior anal-fin rays dark, remaining rays and membrane unpigmented.

Color in life. Based on photographs published by Lucanus (1998: 14), Finley (1998: 129), Anonymous (1998: 210), and on field observations by FCTL. Very similar to preserved specimens, but ground color cream, never light brown; greenish metallic hue on opercle and cleithrum.

Sexual dimorphism. We have not dissected any specimens to confirm their sex, but aquarists who have bred the species in captivity (e.g. James, 2003a, b) mentioned that specimens with elongated dorsal fins are mature males. Presumably mature males examined (MZUSP 64096, 1 of 4; MZUSP 81179, 2) possess the soft portion of the dorsal spine, and the first two dorsal-fin branched rays very elongate. The first branched ray is the longest, followed by the soft portion of the dorsal spine. This results in an anteriorly elongated dorsal fin (see Fig. 3 ; Table 1). See the “Discussion”, for comparisons with another Corydoras that possess elongated dorsal fins.

Popular name. “Waipotá” (both in Tukano and Tuyuka languages).

Habitat and ecological notes. The rio Tiquié, type-locality of C. tukano , is a blackwater river. At the exact type locality the bottom is sandy, with a moderate amount of vegetal debris. Corydoras tukano also was collected at sites with predominantly clay substrates. James (2003a,b) related that in captivity specimens of this species (identified by him as Corydoras sp. cf. reynoldsi ) lay several scattered clutches of large eggs (2.2 mm in size). See also “Discussion”, below.

Distribution. Known only from the rio Tiquié and its tributaries, as the igarapé Cabari. Rio Tiquié is a tributary of the rio Uaupés, in the upper rio Negro basin, Amazonas, Brazil, near the Brazilian/Colombian border ( Fig. 6 ). Most of the specimens studied were collected in the upper rio Tiquié, in the area between Pari-Cachoeira (0°15’N, 69°46’W) and Caruru (0°16’N, 69°54’W). One sample (MZUSP 65689) was collected near Cunuri (0°12’N, 69°22’W), a downstream locality not intensively sampled by the second author or associates. According to Tukano and Tuyuka fishermen, Corydoras tukano occurs thorough the rio Tiquié basin, from its lower course upstream to Caruru, where a major waterfall about 8 m high, the Cachoeira do Caruru, effectively separates the downstream ichthyofauna from the upper section of this river. Again according to Tukano and Tuyuka fishermen, C. tukano is absent upstream of this waterfall. In fact, despite considerable time and effort spent in apparently suitable sites, the second author was unable to collect any C. tukano upstream of the Cachoeira do Caruru.

Etymology. After the Tukano, an Amerindian group from the upper rio Negro and Japurá/Caquetá basins in Brazil, Colombia, and Venezuela. Main cultural features displayed by this ethnic group are the Tukanoan language, the patrilineal clans system, and a diet having as staple foods manioc and fish ( Chernella, 1989; Ribeiro, 1995). The presently known range of C. tukano is entirely within the Tukano territory.

Figures

Fig. 1. Corydoras tukano, holotype, MZUSP 82100, presumably a female, 40.9 mm SL; Brazil, Amazonas state, rio Tiquié, comunidade de Caruru. Caudal-fin margin reconstructed from MZUSP 81194, 37.4 mm SL.

Fig. 2. Corydoras tukano, holotype, MZUSP 82100, presumably a female, 40.9 mm SL; Brazil, estado

Fig. 3. Corydoras tukano, paratype, MZUSP 81179, presumably a mature male, 36.1 mm SL; Brazil,

Fig. 4. Dorsal (left) and ventral (right) views of head and pectoral fins of Corydoras tukano, holotype, MZUSP 82100, 40.9 mm SL; Brazil, estado do Amazonas, rio Tiquié, comunidade de Caruru.

Fig. 5. Orbital region of Corydoras tukano, paratype, MZUSP 81153, showing odontode-bearing platelets around the eye. Odontodes not depicted.

Fig. 6. Upper rio Negro basin and adjoining river basins, showing the distribution of Corydoras tukano (squares). 1- Type locality, rio Tiquié; 2- rio Uaupés; 3 – rio Negro; 4- rio Içana; and 5 – rio Japurá.