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

Astyanax varzeae , new species

( Figs. 2–4 ; 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 40535, 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. 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. 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.

Figures

FIGURE 2. Astyanax varzeae, holotype, MHNCI 11688, 83.1 mm SL, rio São João, rio da Várzea headwaters, an affluent of rio Negro, upper rio Iguaçu basin.

FIGURE 3. Astyanax varzeae, paratype, MCP 40535, 68.2 mm SL, rio São João, rio da Várzea headwaters, an affluent of rio Negro, upper rio Iguaçu basin. In this exemplar, the anterior portion of the black midlateral stripe is expanded, forming a faint second humeral spot.

FIGURE 4. Astyanax varzeae, MHNCI 9146. Lateral view of maxilla (top-left), premaxilla (top-right), and lower jaw (bottom).

Tables

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.

Characters	Holotype	Range	Mean	SD
Standard length (mm)	83.1	43.0−83.1	60.6	10.5
Percents of standard length
Predorsal distance	52.9	51.1−55.2	52.8	1
Prepelvic distance	50.7	49.8−53.9	51.6	1
Prepectoral distance	26.5	26.5−32.0	28.3	1.3
Preanal distance	67.2	64.6−69.7	67.1	1.4
Body depth	31.2	28.7−32.9	31	1.2
Caudal peduncle depth	11.6	10.8−12.2	13.1	11.7
Caudal peduncle length	11.4	10.5−13.9	12.4	1
Dorsal fin length	19.9	19.9−25.9	23.2	1.4
Pelvic fin length	14.9	13.7−15.4	14.4	0.4
Pectoral fin length	19.3	18.9−22.0	20.3	0.8
Anal fin length	15.9	15.0−19.4	17	1
Head length	28	27.1−29.7	28.6	0.7
Percents of head length
Snout length	21	16.4−23.3	20.1	1.6
Upper jaw length	42	35.4−49.4	41.1	2.5
Orbital diameter	34.1	30.9−44.5	37.9	3
Interorbital width	34.6	29.8−37.7	34.5	1.6