Astyanax varzeae, Abilhoa, Vinícius & Duboc, Luiz Fernando, 2007

Abilhoa, Vinícius & Duboc, Luiz Fernando, 2007, A new species of the freshwater fish genus Astyanax (Ostariophysi: Characidae) from the rio Iguaçu basin, southeastern Brazil, Zootaxa 1587, pp. 43-52: 45-48

publication ID

http://doi.org/ 10.5281/zenodo.178471

publication LSID

lsid:zoobank.org:pub:B2CDDEA9-F47C-444F-BA47-DB7D7EC8D49A

persistent identifier

http://treatment.plazi.org/id/D84287E1-954C-AD1C-3BEE-B775FB23AB02

treatment provided by

Plazi

scientific name

Astyanax varzeae
status

new species

Astyanax varzeae  , new species

( Figs. 2–4View FIGURE 2View FIGURE 3View FIGURE 4; Table 1)

Astyanax  sp. F. Haluch & Abilhoa, 2005: 384 (fig. 1), 387 (comparative material).

Holotype. MHNCI 11688, 83.1 mm SL, Brazil, Paraná, Tijucas do Sul, rio São João, rio da Várzea headwaters, an affluent of rio Negro, upper rio Iguaçu basin, approx. 25 ° 55 ’S 49 ° 10 ’W, A. Schwarz, March 1999.

Paratypes. Collected with the holotype: MCP 40535View Materials, 14, 43.9 –72.0 mm SL; MHNCI 9146, 1 c&s, 53.1 mm SL; MHNCI 9147, 15, 43.0– 81.8 mm SL (including 2 c&s).

Diagnosis. The combination of shallow body depth (28.7–32.9 % vs. more than 35 % of SL) and the lower number of branched anal-fin rays (15–20 vs. 20–45) include Astyanax varzeae  in the Astyanax scabripinnis  species complex of Bertaco & Lucena (2006). Astyanax varzeae  differs from A. ojiara  and A. paris  by its shallower body depth (28.7–32.9 % vs. 34.0–40.0% of SL in A. ojiara  and A. paris  ). Shallow body depth (28.7– 32.9 %, mean= 30.1) also differs Astyanax varzeae  from A. ita  (34.3–39.8 %, mean= 37.1), A. rivularis  (35.0– 46.0%), A. chico  (37.3 –43.0%, mean= 40.8), A. tumbayaensis  (39.2–45.3 %, mean= 42.4), A. hermosus  (33.9– 38.7 %, mean= 36.3 in females, 36.1 in males), A. endy  (36.6–42.2 %, mean= 39.7 in females, 38.4 in males), A. pampa  (36.9–42.2 %, mean= 38.7), and A. laticeps  (35.3–40.6 %, mean= 37.9). Astyanax intermedius  can be distinguished from A. varzeae  by its smaller dorsal-fin length (10.7–16.4 %, mean= 13.4 vs. 19.9–25.9 %, mean= 23.2). Astyanax varzeae  differs from A. giton  by its larger head length relative to SL (27.1–29.7 %, mean= 28.6 vs. 21.4–26.3 %, mean= 23.7), and from A. taeniatus  by its shorter snout length compared to head length (16.4–23.3 %, mean= 20.1 vs. 25.3–32.6 %, mean= 28.6). Astyanax varzeae  is distinguished from A. jenynsii  by its larger orbital diameter relative to head length (30.9–44.5 %, mean= 37.9 vs. 24.7–27.6 %, mean= 26.3), and from A. obscurus  by the greater interorbital width (29.8–37.7 %, mean= 34.5 vs. 27.7–28.6 %, mean= 28.2). The presence of bony hooks on all fins but pectoral-fin rays of males separates A. leonidas  and A. troya  from A. varzeae  , and the presence of bony hooks on pelvic and anal-fin rays of males separates A.

totae  , A. cremnobates  and A. brachypterygium  from A. varzeae  . The occurrence of two humeral spots (second one faint) distinguishes A. varzeae  from A. paranae  , A. microschemos  , and A. pelecus  (single humeral spot).

Description. Morphometric data of holotype and paratypes are presented in Table 1. Body moderately elongated, compressed, greatest depth at dorsal fin origin, 3.1 to 3.5 times in SL.

Dorsal profile of head straight. Dorsal body profile between the supraoccipital spine through dorsal-fin origin gently convex, and almost straight from the end of dorsal-fin base to caudal peduncle. Base of dorsal fin straight. Ventral profile of head gently rounded. Body profile from the margin of lower lip to anal-fin origin convex. Anal-fin base straight. Caudal peduncle elongated with dorsal and ventral profiles nearly straight.

Snout profile rounded, shorter than orbital diameter. Postero-ventral edge of third infraorbital distant from preopercle, leaving wide naked border between these bones. Mouth terminal, angled posteroventrally. Maxilla reaching a vertical line through the middle of the orbit, with 1 to 3 (usually 2) tricuspid teeth.

Premaxilla with two tooth rows. Outer row with 3 (2), 4 * (21) tricuspid teeth, with central cuspid developed. Inner row with 5 teeth gently expanded distally, slightly compressed at distal tips. Symphysial tooth narrower and deeper, with 4 or 5 cusps. Second, third and fourth teeth with 5 cusps. Fifth tooth smaller, with 4 cusps. In all teeth central cusp slightly larger than remaining ones. Dentary with 7 teeth. First four anterior teeth larger, usually with 5 cusps, followed by 3 very smaller tricuspid teeth ( Fig. 4View FIGURE 4).

Dorsal-fin rays ii, 9. Posterior margin of dorsal-fin straight. Dorsal-fin origin approximately at middle of SL. Pelvic-fin rays i, 7. Pelvic-fin origin located slightly anterior to vertical through dorsal-fin origin. Pectoral-fin rays 11 (3), 12 (14), 13 * (13). Anal-fin with iii –iv, 15 (1), 16 (5), 17 * (16), 18 (7), 20 (1) rays. Adiposefin located approximately at vertical through insertion of base of last anal-fin rays. Caudal-fin forked, lobes similar in size, slightly rounded, and with 19 principal rays.

Lateral line complete, with 37 (1), 38 (6), 39 * (16), 40 (6), 42 (1) perforated scales. Six series of scales between dorsal-fin origin and lateral line. Four or five series of scales between lateral line and pelvic-fin insertion. Circumpeduncular scales 14 * (4), 15 (7), 16 (19).

In three cleared and stained specimens procurrent caudal-fin rays 8 or 10 dorsal and ventral. First gill arch with 19 gill rakers (7 epibranchial, 9 ceratobranchial, 1 on cartilage between epibranchial and ceratobranchial, and 2 hypobranchial), vertebrae 36, 37 or 38 (18 precaudal and 18, 19 or 20 caudal). Supraneurals 5.

Color in alcohol. Preserved specimens with dorsal and lateral parts of the body medium brown to pale yellowish. Dark chromatophores concentrated on middorsal surface of head and body. Humeral spot narrow and vertically elongated, two scales wide above lateral line. Body with black, pigmented, midlateral stripe extending from humeral region to the median caudal-fin rays. The anterior portion of the stripe expanded, sometimes forming a faint second humeral spot, more clearly visible in smaller specimens ( Fig. 3View FIGURE 3). Fins with scattered dark chromatophores.

Sexual dimorphism. None of the specimens examined have bony hooks on the fins or any other sexually dimorphic feature.

Etymology. The species name, varzeae  , is in reference to the sample locality, rio da Várzea drainage, a tributary of the upper rio Iguaçu basin.

Distribution. Astyanax varzeae  is known only from the rio da Várzea headwaters, an affluent of rio Negro, a tributary of the upper portions of the rio Iguaçu in Paraná State, Brazil.

Ecological notes. Astyanax varzeae  was collected in a headwater stream with clear water, light to moderate current water and bottom with stones, sand and moderate amount of vegetal debris.

TABLE 1. Morphometric data of Astyanax varzeae sp. n., based on the holotype (MHNCI 11688) and paratypes (MHNCI 9146, n = 1; MHNCI 9147, n = 15; MCP 40535, n = 14). SD = standard deviation.

  Holotype   Mean  
        10.5
Percents of standard length        
    49.8−53.9    
    64.6−69.7    
    10.8−12.2    
    10.5−13.9    
    19.9−25.9    
    18.9−22.0    
    15.0−19.4    
    16.4−23.3    
    30.9−44.5    
    29.8−37.7    
MCP

Pontificia Universidade Catolica do Rio Grande do Sul

Kingdom

Animalia

Phylum

Chordata

Class

Actinopterygii

Order

Characiformes

Family

Characidae

Genus

Astyanax

Loc

Astyanax varzeae

Abilhoa, Vinícius & Duboc, Luiz Fernando 2007
2007
Loc

Astyanax

Haluch 2005: 384
2005