Astyanax totae, a new characid species (Teleostei: Characidae) from the upper rio Iguaçu basin, southeastern Brazil

A new species of characid fish, Astyanax totae, is described from a small tributary in the upper drainage of the rio Iguacu, Parana basin, Brazil. The new species is distinct from most species of Astyanax by the vertically elongated humeral spot, slightly expanded above the lateral line to posterodorsal margin of opercle, followed by a midlateral dark stripe expanded from the humeral region to the median caudal-fin rays, maxilla with 2 to 5 teeth (usually 3) and 15 to 18 branched anal-fin rays.


Introduction
The genus Astyanax Baird & Girard, 1854 is diverse and widespread in freshwaters of South America, including about one hundred nominal species (Lima et al., 2003).The systematic of the genus is still unresolved and the taxonomic status of some species is not completely clear.
In the last few years, the diagnoses of Astyanax-like forms that inhabit fast-water streams have shown body shape characters similar to the subspecies of Astyanax scabripinnis diagnosed by Eigenmann (1921Eigenmann ( , 1927) ) and to the A. scabripinnis species complex of Moreira-Filho & Bertollo (1991), with an elongated body (2.6 to 3.6 body depth in SL), low anal-fin ray counts (less than 25), head heavy and body deepest and heaviest over middle of pectoral fins.These body shape characters are apparently common to other Astyanax-like forms that inhabit fast-water streams, and some morphometric and karyotypic studies have found that these isolated populations are in fact undescribed species (Moreira Filho & Bertollo, 1991;Bertaco & Malabarba, 2001;Melo, 2001), leading us to believe that Eigenmann's definition of A. scabripinnis should be investigated, as stated by Bertaco & Malabarba (2001).
During a field expedition to the upper portions of the rio Iguaçu basin, a new characid species was collected that fits the morphological features of the A. scabripinnis species complex.As a contribution to the knowledge of this poorly known ichthyofauna, we herein describe this species.
Measurements and counts were taken following Fink & Weitzman (1974).All measurements were taken as straight-line distance using calipers, and were expressed as percentage of SL, except for those taken in the head, which are recorded as percentage of the head length.For counts recorded in the description, the frequency of each count is provided in parenthesis, and an asterisk indicates those of the holotype.Specimens were cleared and stained for vertebral, supraneurals, gill-rakers, teeth and procurrent caudal-fin-ray counts according to

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the method of Taylor & Van Dyke (1985).Vertebrae count includes those corresponding to the Weberian apparatus and the terminal centrum was counted as one vertebrae.
The nomenclature of the comparative material from the rio Iguaçu basin follows Severi & Cordeiro (1994) (2001).Morphometric data of A. intermedius and A. janeiroensis follow Melo (2001).Comparative material from the A. scabripinnis species complex from other drainages was analyzed (Fig. 1).

Astyanax
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 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.

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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.
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),

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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.

Discussion
Four Astyanax species were previously described from the rio Iguaçu basin: A. gymnogenys Eigenmann, 1911, A. scabripinnis paranae Eigenmann, 1927, A. leonidas Azpelicueta et al., 2002, and A. ita Almirón et al., 2002.The number of analfin rays separates A. totae (15 to 18) from A. gymnogenys (21 to 22) and A. ita (23 to 28), and the presence of only one maxillary tooth distinguish A. leonidas from the new species (2 to 5, usually 3).Furthermore, mature males of A. leonidas possess bony hooks in rays in all fins, except in the dorsal fin, whereas A. totae shows small hooks on the pelvic and anal-fin.
Among other species occurring in the rio Iguaçu basin recorded by Severi & Cordeiro (1994)

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of males, unlike the new species.Astyanax totae is distinguished from Astyanax sp.F by the shorter snout length compared to head length (14.6-24.1%,mean=19.9,SD=2.2 versus 24.6-32.6%,mean=28.2,SD=2.1).Astyanax totae differs from A. janeiroensis and Astyanax aff.scabripinnis (from coastal drainage of southeastern Brazil -MHNCI 7824, MHNCI 7844, MHNCI 7858) also by the lower number of branched anal-fin rays (15-18 versus 19-24 in A. janeiroensis and 19-23 in Astyanax aff.scabripinnis) and by the humeral spot vertically elongated, slightly expanded above the lateral line until the opercle margin.In these species, like Astyanax sp.D, the humeral spot is well-defined, black and round, with vertically elongated line extended anteroventrally.Furthermore, the number of gill rakers in the ceratobranchial is lower in A. totae (9) in comparison with Astyanax aff.scabripinnis (10) from coastal drainage of Paraná.In addition, A. totae has 2 gill rakers in the hypobranchial, whereas Astyanax aff.scabripinnis has one.The two cleared and stained specimens of A. totae also have lower number of procurrent caudal fin rays.
Recent collecting efforts in the upper rio Iguaçu basin yielded seven species of Astyanax (Ingenito et al., 2004).Only two species fit the morphological features of the A. scabripinnis species complex: A. totae and Astyanax sp.D. Astyanax totae clearly differs from the second species, and is the first species of the genus described for the rio Iguaçu headwaters.The fact that the specimens are so far known only in one stream indicate that conservation programs should be established.
and from A. rivularis by the lower number of branched anal-fin rays (15-18 versus 21 in A. scabripinnis and 20-25 in A. rivularis).Characters distinguishing A. jenynsii, A. laticeps, A. intermedius, and A. paranae from A. totae are discussed under diagnosis.Astyanax longirostris was transferred to the monophyletic genus Deuterodon by Lucena & Lucena (2002) based on the shape of the maxillary bone and tooth arrangement.

Fig. 4 .
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 .
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.