Astyanax ajuricaba, Marinho & Lima, 2009

Marinho, Manoela M. F. & Lima, Flávio C. T., 2009, Astyanax ajuricaba: a new species from the Amazon basin in Brazil (Characiformes: Characidae), Neotropical Ichthyology 7 (2), pp. 169-174 : 170-173

Astyanax ajuricaba , new species

Fig. 1

Astyanax sp. Géry, 1992: 77 , fig. 12 (“Lago do Castanha [= Castanho], Solimões à environ 30 km au S.-O. de Manaus”, Amazonas, Brazil; brief description, discussion).

Astyanax sp. 3 . Cabalzar et al., 2005: 180 (upper rio Tiquié, rio Negro system, Amazonas, Brazil; figure; habitat notes).

Holotype. MZUSP 100231 , 65.5 mm SL: Brazil, Amazonas State, stream tributary to rio Tiquié, Serra do Mucura village , 0°10’07”N 69°07’46”W, 10 Sep 2006, F. C. T. Lima et al.

Paratypes. Brazil, Amazonas State, rio Negro drainage : MZUSP 92142 , 22 , 2 c&s, 59.2-71.9 mm SL ; ANSP 189235 , 5 , 59.3-68.3 mm SL ; INPA 31196 , 5 , 64.3-66.5 mm SL, same data as the holotype . MZUSP 92365 , 3 , 62.8-88.6 mm SL, rio Tiquié, Serra do Mucura village , 0°10’N 69°07’W, 30 Aug-12 Sep 2006 , F. C. T. Lima et al. MZUSP 92252 , 2 , 66.4-68.1 mm SL, Doe Sehrako lake, rio Tiquié, below Pirarara-Poço village , 0°08’N 69°12’W, 07 Sep 2006 , F. C. T. Lima et al .. MZUSP 81190 , 1 , 69.4 mm SL, rio Tiquié, Boca do Sal village , 0°16’22’’N 69°54’3’’W, 25 Oct 2002 , N. P. Marques. MZUSP 62055 , 1 , 65.0 mm SL, rio Negro, Tapera , 0°31’S 65°1’W, 2 Nov 1972 , Expedição Permanente à Amazônia. MZUSP 96045 , 10 , 54.4-66.5 mm SL, 1 c&s, 60.6 mm SL, Santa Isabel do Rio Negro, lagoon at island in the rio Negro , 0°31’S 65°1’W, 14 Nov 1972 , Expedição Permanente da Amazônia . MPEG 694 , 5 , 34.5- 61.2 mm SL, rio Negro, lagoon at Ilha de Tamanquaré , 2°53’S 60°31’W, 11 Nov 1984 , M. Goulding. Pará, rio Tapajós drainage : MZUSP 21877 , 83 , 51.7-64.7 mm SL, 3 c&s, 51.5-57.5 mm SL ; USNM 394515 , 5 , 55.7-62.7 mm SL; DZSJRP 11286, 5, 59.3-64.7 mm SL ; MCP 43346, 5 , 52.7 -60.0 mm SL, rio Tapajós, Maloquinha, near Itaituba , c. 4°17’S 55°59’W, 11-13 Nov 1970 , Expedição Permanente à Amazônia. MZUSP 18280 , 6 , 62.5-95.2 mm SL, Igarapé Centrinho, Barreirinho, near São Luís , c. 4°26’S 56°14’W, 24 Nov 1970 , Expedição Permanente à Amazônia. MZUSP 18248 , 24 , 52.4-63.1 mm SL, Aveiro, igarapé Açu , 3°35’S 55°20’W, 30 Oct 1970 , Expedição Permanente à Amazônia. MNRJ 33068 , 1 , 62.3 mm SL, Itaituba, igarapé Jacaré (tributary of rio Tapajós ), Transamazônica road, 4°26’30.9”S 56°14’10.8”W, 28 Oct 2008 , P. Buckup, C. Zawadzki, L. Fries, F. Carvalho & F. Jerep.

Diagnosis. Astyanax ajuricaba can be diagnosed from all congeners, and in fact from all remaining characids by its unique color pattern consisting of the combination of presence of a conspicuous, narrow dark midlateral stripe, a single elongated humeral spot, and upper caudal-fin lobe and middle caudal-fin rays dark, with a clear, rounded ocellated spot present dorsally at anterior third of caudal-fin lobe. See the Discussion for further details.

Description. Morphometric data for Astyanax ajuricaba is summarized in Table 1. Body elongated, compressed laterally. Largest specimen examined 95.2 mm SL. Greatest body depth immediately anterior to dorsal-fin origin. Dorsal profile of head slightly convex from snout tip to vertical through anterior nostril, and straight from that point to tip of supraoccipital spine. Predorsal profile of body slightly convex, posteroventrally slanted and straight from dorsal-fin origin to adipose-fin origin, slightly concave between latter point and origin of anteriormost dorsal procurrent caudal-fin ray. Ventral profile of head and body convex from lower lip to anal-fin origin; body profile along anal-fin base straight, posteroventrally inclined, and slightly concave between analfin terminus to anteriormost ventral procurrent caudal-fin ray.

Jaws equal, mouth terminal; posterior terminus of maxilla reaching vertical through anterior third of orbit. Premaxillary teeth in two rows, with midcentral cusp more developed than remaining cusps; outer teeth row with 4(6), 5*(44), or 6(1) tricuspid teeth; inner tooth row with 4(5), 5*(41) or 6(5) tri- to pentacuspid teeth. Maxillary with 1(5) or 2(2) uni- to tricuspid teeth; dentary with four large tetra- to pentacuspid teeth, followed by series of 7-10 small, unicuspid teeth ( Fig. 2 ).

Dorsal-fin rays ii,9, not including small ossification anterior to first unbranched ray, discernible only in cleared and stained specimens; first unbranched ray about one-half length of second unbranched ray. Dorsal fin origin slightly ahead from midbody, at vertical through anterior third of pelvic-fin base, and base of its last ray at vertical through tip of adpressed pelvic fin. Tip of adpressed dorsal fin approximately at vertical through insertion of 8 th to 10 th branched anal-fin rays. First dorsal-fin pterygiophore inserting posterior to neural spine of 10 th (6) vertebrae. Pectoral-fin rays i,13*(27), 14(19), or 15(4). Adipose fin located approximately at vertical through insertion of 18 th to 24 th branched anal rays. Pelvic-fin rays i,7. Pectoral fin not reaching pelvic-fin insertion. Pelvic fin not reaching anal-fin origin.Anal-fin rays iv(5) or v(1), 23(2), 24(9), 25(21), 26*(13), or 27(2). Last unbranched anal-fin ray and 1 th and 2 th branched rays longer; 3 th to 6 th branched rays decreasing abruptly in size; remaining branched anal-fin rays decreasing slightly in size. First anal-fin pterygiophore inserting posterior to neural spine of 18 th (6) vertebrae. Principal caudal-fin rays i,15,i(2), i,17,i*(49). Dorsal procurrent caudal-fin rays 12(1), 13(2), or 14(1), and ventral procurrent caudal-fin rays 10(3) or 11(1). Caudal-fin forked, lobes pointed. Scales at base of caudal fin, not extending over lobes. Supraneurals 4(3) or 5(3); upper portion with relatively poorly developed bony lamellae, more developed in specimens from rio Negro basin. Vertebrae 36(5) or 37(1). First gill arch with 2(4) or 3(1) hypobranchial, 9(1), 10(2), or 11(2) ceratobranchial, 1(5) on cartilage between ceratobranchial and epibranchial, and 7(4) or 8(1) epibranchial gill-rakers. Four branchiostegal rays: three branchiostegal rays originating at anterior ceratohyal and one at posterior ceratohyal.

Scales cycloid, with few radii along posterior border. Lateral line complete with 37(3), 38*(13), 39(22), 40(7), or 41(1) scales. Scale rows between dorsal-fin origin and lateral line 7(3), 8*(48); scale rows between lateral line and pelvic-fin origin 5. Predorsal scales 13(14), 14*(29), 15(4), or 16(2). wide, longitudinal dark band extending vertically through four scale rows: at lateral line and three scale rows above it, gradually narrowing towards and connecting to rounded faint blotch at caudal peduncle. Middlateral narrow dark stripe conspicuous, situated at junction of epaxial and hypaxial muscles, extending from first humeral blotch to caudal peduncle, but faint between humeral spots. Scattered dark chromatophores at posterior half of lower portion of body, between lateral line and anal-fin base, concentrating along margins of myosepta. Upper caudalfin lobe and middle caudal-fin rays darkened, except for clear rounded area (hereby defined as ocellated spot) present dorsally at anterior third of caudal-fin lobe. Black pigmentation on upper caudal-fin lobe and middle caudalfin rays not homogeneous, with intensity varying among specimens. Lower caudal-fin lobe and remaining fins with scattered dark chromatophores.

Color in life. Based on photographs of fresh collected paratypes, MZUSP 92252. Ground color pattern silvery, with top of head and dorsum dark grey. Narrow midlateral stripe not discernible due to silvery pigmentation. Upper half of eye yellowish. Caudal-fin ocellated spot, dorsal fin, adipose fin, and first anal-fin rays yellow.

Geographical variation. The only character to distinguish specimens of Astyanax ajuricaba from the rio Negro and rio Tapajós basins was the number of supraneural bones. Cleared and stained specimens from the rio Negro basin possess five, while specimens from rio Tapajós possess four supraneural bones.

Circumpeduncular scale rows 14. Single row of 5-8 scales covering base of anteriormost anal-fin rays.

Color in alcohol. Overall ground coloration of body pale. Top of head dark brown. Infraorbital, opercular areas and pectoral girdle silvery. Infraorbitals 5 and 6 and upper half of opercle with scattered, relatively large, dark chromatophores. Lower lip and anterior half of maxilla with dense concentration of small dark chromatophores. Gular area clear. Middorsal area dark brown. Scales above midlateral line, at dorsolateral portion of body bordered by dense concentration of small dark chromatophores, forming reticulated pattern. Humeral spot well defined, rectangular, vertically-elongated, extending vertically two scales rows above and one scale row below lateral line, and two scale rows horizontally. Humeral spot with darker area at level of midlateral line, extending beyond its anterior margin. Faint, Sexual dimorphism. No apparent sexual dimorphism was observed. Fin hooks, the usual dimorphic feature among characids (Malabarba & Weitzman, 2003), were not found in any specimen.

Ecological notes. The type-locality of Astyanax ajuricaba is a black-water, terra-firme forest stream about 4-5 meters wide and 0.5-1.0 meters deep, with a predominantly sandy bottom. Specimens MZUSP 92252 were collected in a large oxbow lake of the rio Tiquié. According to field notes by P. Vanzolini, specimens from the igarapé Centrinho, in the rio Tapajós basin (MZUSP 18280), were collected in a small terra-firme stream, a habitat apparently similar to the type-locality.

Etymology. The specific epithet honors Ajuricaba, paramount chief of the Manau Indians, which formerly inhabited in the middle rio Negro area. During the decade of 1720, Ajuricaba leaded an unsuccessful attempt to resist the assaults of Portuguese slavers, which eventually lead to the defeat of his nation and his imprisonment. Ajuricaba averted a trial as a rebel by plunging in shackles into the rio Negro waters, and for such act of bravery he became a symbol of the resistance of the Indians against the Portuguese oppression ( Hemming, 2004).

Popular names. Bose puri (Tukano language), Buse puri (Tuyuka language).

Distribution. Astyanax ajuricaba is known from the upper rio Negro basin at the rio Tiquié, a large tributary from the rio Uaupés, the middle and lower rio Negro areas at Santa Isabel do Rio Negro and Anavilhanas archipelago, respectively, and the lower rio Tapajós basin, Brazil. Géry (1992) recorded Astyanax ajuricaba (as Astyanax sp. ) from the lago do Castanho (c. 3°23’S 60°13’W), a large lake connected to the better-known lago Janauacá, both of which are situated at the floodplains of the rio Solimões, in the central Amazon basin ( Fig. 3 ).

Figures

Fig. 1. Astyanax ajuricaba, holotype, MZUSP 100231, 65.5 mm SL: Brazil, Amazonas, rio Tiquié, Serra do Mucura village.

Fig. 2. Astyanax ajuricaba, MZUSP 96045, 60.6 mm SL; scanning electron micrographs (SEM) showing right premaxillary (a) and dentary teeth (b) in mesial view. Scale bar: (a): 100 µm; (b):200 µm.

Fig. 3. Northern South America showing known localities of Astyanax ajuricaba. 1. Type locality. 2: Lago do Castanho, locality of the specimen examined by Géry (1992).