Astyanax totae, Haluch & Abilhoa, 2005

Haluch, Carolina Ferreira & Abilhoa, Vinícius, 2005, Astyanax totae, a new characid species (Teleostei: Characidae) from the upper rio Iguaçu basin, southeastern Brazil, Neotropical Ichthyology 3 (3), pp. 383-388 : 384-385

Astyanax totae , new species

( Figs. 2-5 ; Table 1)

Holotype. MHNCI 10305 , 61.1 mm SL, Brazil, Paraná, Balsa Nova, distrito do Bugre, rio Cascata , tributary of rio Tortuoso , an affluent of rio Iguaçu , 25°29’S, 49°39’W, D. P.Azevedo Filho & E. L. Rosa, 26 May 2002.

Paratypes. (Same locality and collectors as holotype): MHNCI 10306 , 21 , 34.4-73.4 mm SL (2 c&s), 26 May 2002 . MHNCI 10338 , 54 , 32.3-71.3 mm SL, 9 Jan 2002 . MCP 37562, 8 , 49.1-81.9 mm SL, 11 Jul 2002 . MCP 37561, 15 , 39.2-64.3 mm SL, 9 Jan 2002 . MCP 37560, 4 , 47.1-69.2 mm SL, 10 Jan 2002 . NUP 4099 , 16 , 41.9-56.3 mm SL, 23 Jun 2002 . MNRJ 28652 , 11 , 36.9-66.3 mm SL, 9 Jan 2002 .

Diagnosis. Astyanax totae differs from other species of the genus by the lower number of branched anal-fin rays (iii-v, 15-18, mean=16.7, n=30, versus 20-45 in most species of the genus). Other species of Astyanax with the same number of branched anal-fin rays are A. jenynsii (13-15, n=3), A. laticeps (18-21, n=5), A. intermedius (14-21, n=89), A. brachypterygium (13-15, n=43), A. cremnobates (15-17, n=59), A. leonidas (17- 21, n=16), and A. paranae (17-23). Astyanax totae differs from the syntypes of A. jenynsii (NMW 57534, 3) and types of A. laticeps (ANSP 21852, 1; ANSP 21743, 4) by the shorter upper jaw length compared to head length (21.8-28.7%, mean=26.6, SD=1.3 versus 35.9-39.5%, mean= 37.4 in A. jenynsii and 43.4-45.7%, mean= 44.6 in A. laticeps ). The upper jaw length is also longer in A. intermedius (37.5-53.1%, mean=44.4, SD=2.7). Astyanax totae is distinguished from A. brachypterygium and A. cremnobates by the larger orbital diameter relative to head length (25.4-42.6%, mean=35.7, SD=4.1 versus 24.8-34.8%, mean=29.0 in A. brachypterygium , and 28.1-35.4%, mean= 32.1 in A. cremnobates ; Fig. 4 ). Although the orbital diameter in A. totae partially overlaps the range of A. brachypterygium and A. cremnobates , significant differences using one-way analysis of variance test were found among the species (F=46.83, P<0.001; Fig. 5 ). Astyanax totae is further distinguished from A. brachypterygium and A. cremnobates by the presence of a single humeral spot vertically elongated (versus two black humeral spots, second one diffuse). The presence of 2 to 5 (usually 3) maxillary teeth distinguishes A. totae from A. leonidas that has only one maxillary tooth long and slender. It was not possible to analyze the type material of A. paranae , but some characteristics present in the original description ( Eigenmann, 1914:47) discriminate the new species from A. paranae : the larger orbital diameter (25.4-42.6%, mean=35.7, SD= 4.1 in A. totae versus “eye 5 in the head in the old” in A. paranae ) and the larger snout length compared to head length (14.6-24.1%, mean=19.9, SD= 2.2 in A. totae versus “snout 3.5” in A. paranae ).

Description. Morphometrics of holotype and 29 paratypes are presented in Table 1. Body moderately elongated, compressed. Greatest body depth at dorsal fin origin, 2.8 to 3.4 times in SL.

Dorsal profile of head straight. Predorsal profile of body slightly convex from the supraoccipital spine through dorsalfin origin, and almost straight from the end of dorsal-fin base to caudal peduncle. Dorsal-fin base straight, posteroventrally inclined. Ventral profile of head and body convex from lower lip to anal fin origin. Body profile along anal fin base straight. Caudal peduncle elongated with dorsal and ventral profiles nearly straight.

Snout prominent and rounded, shorter than orbital diameter. Posteroventral 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 2-5 tricuspid teeth (mostly 3*, n=20), decreasing in size anteroposteriorly.

Premaxillary teeth in two rows. Outer row with 2 (1), 3 (9), 4* (19) or 5(1) 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 to 7 cusps. Fifth tooth smaller, with 3 or 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.

Dorsal-fin rays ii, 9. Posterior margin of dorsal fin slightly rounded. Dorsal-fin origin distance from snout tip nearly equal or larger than caudal-fin base. Pelvic-fin origin situated anterior to vertical through dorsal-fin origin, with 8 rays. Tip of pelvic fin reaching anal-fin origin only in small specimens. Pectoral-fin rays 10 (2), 11 (3), 12 (8), 13* (15), 14 (2). Pectoralfin distal tips not reaching pelvic-fin, except in small specimens. Anal fin with iii-iv, 15 (4), 16* (7), 17 (14), 18 (5) rays. Caudal fin forked, lobes similar in size, slightly rounded.

Lateral line complete, with 34 (1), 35 (4), 36 (13), 37 (7), 38* (5) perforated scales. Six series of scales between dorsal-fin origin and lateral line, not including scale of predorsal series situated just anterior to first dorsal-fin ray. Four series of scales between lateral line and pelvic-fin insertion. Circumpeduncular scales 15 (3), 16 (2), 17 (10), 18* (11), 19 (3).

In two cleared and stained specimens procurrent caudalfin rays 7 dorsal and 10 ventral. First gill arch with 19 gill rakers (7 epibranchial, 9 ceratobranchial, 1 on cartilage between epibranchial and ceratobranchial, and 2 hypobranchial), vertebrae 35 or 36 (16 or 17 precaudal and 19 caudal).

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 vertically elongated, slightly expanded above the lateral line to posterodorsal margin of opercle, followed by a midlateral dark stripe extended from the humeral region to the median caudal-fin rays. Lateral stripe placed on two series of scales, wider on caudal peduncle. Humeral spot narrow, three scales wide above lateral line. All fins hyaline, with scattered dark chromatophores pigmentation.

Sexual dimorphism. The presence of small hooks on the pelvic fin and anal fin of males is the only external sexually dimorphic feature found in this species.

Etymology. The specific epithet totae comes from Tota, nickname of Adelinyr Azevedo de Moura Cordeiro, in recognition of her contribution to MHNCI fish collection.

Distribution. Known only from the type locality, rio Cascata, tributary of rio Tortuoso, an affluent of the rio Iguaçu basin in Paraná State, Brazil.

Ecological notes. Astyanax totae 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. The most frequent food items found in fifteen stomachs were microcrustaceans (Cladocera and Copepoda), insect larvae ( Chironomidae ), adult insects and plants fragments (probably allochthonous material). Underwater observations through snorkeling in pool environments identified small groups of individuals collecting food items carried by the current (drift) or feeding on items coming from the forest adjacent to the river. The fact that the stream flows within a remaining fragment of Araucaria Forest in the First Paraná Plateaux is important for the foraging behavior of the species herein described, since some important food items are directly and indirectly dependent on the forest covering.

Figures

Fig. 2. Astyanax totae, holotype, MHNCI 10305, 61.1 mm SL, rio Cascata, tributary of rio Tortuoso, an affluent of the rio Iguaçu.

Fig. 3. Astyanax totae, MHNCI 11248, 56.3 mm SL. Maxilla (top-left), premaxilla (top-right) and lower jaw (bottom); lateral view; right side; scale 1.0 mm.

Fig. 4. Orbital diameter as function of Head Length in Astyanax totae, A. cremnobates and A. brachypterygium. Note that the confidence intervals (95%) do not overlap in A. totae and A. brachypterygium, indicating significant difference. In head lengths of about 8 to 21 mm the 95% confidence intervals do not overlap in A. totae and A. cremnobates, indicating a significant difference in these size ranges.

Fig. 5. Anova box-whisker plots of the Orbital diameter as a percentage of Head Length in Astyanax totae, A. cremnobates and A. brachypterygium. Significant differences using oneway analysis of variance test were found among the species (F=46.83, P<0.001). Mean represented by squares, and confidence intervals (95%) as lateral bars of box-whisker plots. Asterisks represent extreme values.