Three new species of Astyanax from drainages of southern Brazil ( Characiformes : Characidae )

Three new species of Astyanax are described from southern Brazil: A. dissensus and A. xiru from the laguna dos Patos system and rio Uruguay basin, the first species also occurring in the rio Tramandaí system, and A. procerus from the laguna dos Patos system. Astyanax procerus and A. xiru possess outer row premaxillary teeth pentacuspid and inner row heptacuspid, maxillary with one trito pentacuspid teeth, 18-23 branched anal-fin rays, and two humeral spots. Astyanax procerus has the largest body depth (38.3-46.0% of SL), while A. xiru has the lowest body depth (32.5-37.5% of SL) among the three species. The characters combination can distinguish these species from its congeners. Astyanax dissensus distinguish from Astyanax species by the presence of one developed heptacuspid teeth on maxillary, 22-28 branched anal-fin rays, 35-39 perforated scales along the lateral line, two humeral spots, conspicuous lateral band continuous on middle caudal rays, 6-7 scale row between dorsal-fin origin and lateral line, and head length 22.7-27.3% of SL. All three species has the predorsal region of the body scaled. An identification key to the species of Astyanax species from the rio Uruguay basin, and laguna dos Patos and rio Tramandaí systems is provided.


Introduction
The genus Astyanax Baird & Girard is a speciose group of characiform fishes, comprising 138 valid species (Eschmeyer, 2012), and occurring in all Neotropical drainages from the Colorado River, Texas and New Mexico, USA (Ornelas-Garcia et al., 2008) to rio Colorado, northern of Patagonia, Argentina (Menni, 2004;López et al., 2008).Astyanax not represents a monophyletic entity as recent phylogenetic hypotheses, using morphological characters (Mirande, 2010) and molecular data (Javonillo et al., 2010;Oliveira et al., 2011).Due to it, the genus has been defined by a characters combination proposed nearly a century ago by Eigenmann (1921Eigenmann ( , 1927)), as two rows of premaxillary teeth, five teeth in the inner premaxillary series, lateral line complete, adipose fin present, and caudal fin naked, but all these characters are also shared by other Characidae genera (e.g., Hyphessobrycon Durbin, Markiana Eigenmann, Moenkhausia Eigenmann).

Material and Methods
Counts were taken as described by Fink & Weitzman (1974) and Bertaco & Lucena (2006).Counts of vertebrae, supraneurals, and procurrent caudal-fin ray counts were taken from cleared and stained (c&s) specimens prepared according to Taylor & van Dyke (1985).Tooth counts were taken in all specimens included in the table.Vertebral counts include the four vertebrae of the Weberian apparatus, and the terminal centrum counted as a single element.In the descriptions, an asterisk indicates counts of the holotype and the frequency of each count is provided in parentheses after the respective count.Lower and upper jaws of c&s specimens were prepared for scanning electronic microscopy.
Measurements were taken point to point with a caliper on the left side of specimens whenever possible.Measurements are expressed as percentage of standard length (SL) except for subunits of the head which are recorded as percentage of head length (HL) and follows Fink & Weitzman (1974).In the material examined, the catalog number is followed by the total number of the lot and, in parentheses, the number of specimens counted and measured and respective length range.In cases without parentheses, the range length corresponds to the smallest and largest specimens of the lot.
The laguna dos Patos system includes laguna dos Patos, laguna Mirim and all their tributaries, according to Malabarba (1989).The coastal plain of the rio Tramandaí drainage follows the definition of Malabarba & Isaia (1992).The almost fourteen tens valid species of Astyanax, the broad geographical distribution these species, the limited variability in morphological and color pattern among them, and the lack of a taxonomic study of the genus makes the diagnosis of new species too complicated.In addition, the descriptions of most of them are very limited, mainly of the species oldest.As a result, in the text, the Diagnoses include only the species described from the same drainage(s) where the news species occur.In the Discussion section we expand the comparison to with the species that occur in neighboring drainages, and in the São Francisco basin.With this we believe have diminished the likelihood of the new species are already described from the basins of the rio Amazonas, rio Tocantins-Araguaia, rivers of Guianas and trans-Andean basins.If this will be confirmed in the future, it would be a rare case of disjunction distribution.Reported cases of species with wide distribution so surely lack a thorough taxonomic analysis.The differences with the other species from the above mentioned basins will be made with the presentation of a set of characters based on comparative material examined and literature data.

Astyanax dissensus Lucena &Thofehrn, new species Figs. 1-2
Astyanax sp. 2. -Becker et al., 2013: 82 (listed).Two tooth rows in premaxilla; outer row with 2(2), 3(57)*, 4(14), or 5(2) pentacuspid teeth, central cusp longer; inner row with five teeth, gradually decreasing in length from the first to fifth with seven to nine cusps, except the first teeth with asymmetric five cups ; central cusp twice as long and broad as others cusps.Maxilla with one tooth bearing seven cusps (in some specimens one of two lateral cusp may be worn.In this case, taking six cusps); central cusp slightly broader than others.Dentary with nine to ten teeth.Five or six anteriormost dentary teeth decreasing gradually, first four or five hexacuspid, fifth or sixth tetracuspid teeth; remaining three or four, smaller, uni-to tricuspid (Fig. 2).
Lateral line complete with 35(2), 36(22), 37(40)*, 38(8), or 39(4) scales.Scale rows between dorsal-fin origin and lateral line 6(62)*, or 7(17); scale rows between lateral line and pelvic-  Color in alcohol.Dorsal and dorsolateral portions of head and body dark brown.Body with black, midlateral stripe (silvery in some specimens probably due to fixation) placed on one to one and half series of scales extending from the second humeral spot to caudal-fin base; narrowing between the second humeral spot and opercle (region between spots pale in some specimens).Midlateral body stripe slightly expanded dorsally and ventrally to caudal-fin base, forming small caudal spot; dark pigmentation present on middle caudal-fin rays.Two humeral spots.Anterior one, conspicuous, vertically elongate with superior portion somewhat wider.Second humeral spot large, occasionally faint, not ventrally surpassing lateral line.Fins with a few dispersed dark chromatophores (Fig. 1).

Sexual dimorphism.
Males with fine and delicate, bony hooks on pelvic-fin and anal-fin rays.One paired bony hook per lepidotrichia in last unbranched ray and from the first to eleventh to twelfth anal-fin branched rays; the first seven or eight on upper third portion of rays; the remaining restricted to distal portions of rays.Hooks on the pelvic-fin are distributed in first three or four branched rays.Gill glands (Burns & Weitzman, 1996) were not found on first gill arch in either males or females.
Distribution.Astyanax dissensus is known from the laguna dos Patos system and rio Uruguay drainage (Fig. 3).One specimen was captured from coastal lagoon of rio Tramandaí system (MCP 21119).Astyanax dissensus appears to be rare in the rio Tramandaí system because although the sampling efforts in the region it is not mentioned in the Malabarba et al. (2013).
Etymology.The specific epithet dissensus from Latin, disagreement, in reference to the larger maxillary heptacuspid tooth peculiar to the species and unusual in Astyanax species.Two tooth rows in premaxilla; outer row with 4(4), 5( 16)*, or 6(9) pentacuspid teeth, central cusp longer; inner row with five teeth, gradually decreasing in length from the first to fourth, last distinctly smaller, with six to seven cusps; except the first teeth with asymmetric five cups and the last with five or six cusps, central cusp twice as long and broad as others cusps.Maxilla with one tooth bearing four or five cusps, central cusp longer.Dentary with nine to ten teeth.Five anteriormost dentary teeth decreasing gradually, penta-to hexacuspid; remaining four or five smaller, tetra-, tricuspid or, rarely, unicuspid.Central cusp in all teeth two to three times as long and broad as other cusps.All cusp tips slightly curved posteriorly towards inside mouth (Fig. 5).
Color in alcohol.Dorsal and dorsolateral portions of head and body dark brown.Dark chromatophores scattered on lateral portion of head, more densely concentrated on snout and anterior border of eye.Dorsal portion of body densely pigmented.Body with black, midlateral stripe extending from the second humeral spot to caudal-fin base; dark pigmentation present on middle caudal-fin rays.Midlateral body stripe slightly expanded dorsally and ventrally to caudal-fin base.Two humeral spots.Anterior one, conspicuous, vertically elongate with superior portion wider, located over fourth to fifth vertical series of scales, extending over two to three horizontal series of scales above lateral line; inferior portion of spot narrow and curved, sometimes with constriction at the junction with the upper portion, (one to two scales pigmented), extending over one to two horizontal series of scales below lateral line.Second humeral spot large, not ventrally surpassing lateral line, extending over three horizontal series and two to three vertical series of scales.Region between spots pale.Fins with dispersed dark chromatophores (Fig. 4).
Distribution.Astyanax procerus is known from the upper and middle rio Taquari-Antas and rio Jacuí, laguna dos Patos system, Rio Grande do Sul, Brazil (Fig. 6).
Etymology.The specific epithet procerus from Greek, means tall, in reference the high body depth of the species.An adjective in apposition.

Astyanax xiru Lucena, Castro & Bertaco, new species Figs. 7-8
Astyanax obscurus Bertaco & Lucena, 2010: 11 (in part).Description.Morphometric data summarized in Table 1.Body compressed and elongate, with greatest body depth anterior to dorsal-fin origin.Dorsal profile of head straight or slightly convex from posterior nostril to tip of supraoccipital spine.Dorsal body profile convex from tip of supraoccipital spine to base of last dorsal-fin ray; straight from latter point to adipose fin origin.Ventral profile of body slightly convex from vertical through posterior nostril to pelvic-fin origin, nearly straight to anal-fin origin, and posterodorsally slanted along anal-fin base.Caudal peduncle elongate, nearly straight to slightly concave in the dorsal and ventral margins.Snout rounded from margin of upper lip to vertical through anterior nostrils.Mouth terminal, jaws isognathous.Maxilla extending posteriorly to vertical through anterior margin of orbit.
Two tooth rows in premaxilla; outer row with 4(8)*, 5(5) or distinct combinations considering left/right sides, 4/5; 6/4 or 6/5 pentacuspid teeth, central cusp longer; inner row with five teeth, gradually decreasing in length from the first to fourth, last distinctly smaller, with seven cusps; except the first tooth with asymmetric five cups (3+1+1) and the last with five or six cusps; central cusp twice as long and broad as others cusps.Maxilla with one tooth, tri-to pentacuspid, with central cusp longer.Dentary with nine to ten teeth.Five anteriormost dentary teeth decreasing gradually, hexa-to heptacuspid; remaining four or five smaller, tetra-or pentacuspid; last two unicuspid.Central cusp in all teeth two to three times as long and broad as other cusps.All cusp tips slightly curved posteriorly towards inside mouth (Fig. 8).
Color in alcohol.Dorsal and dorsolateral portions of head and body dark brown.Dark chromatophores scattered on lateral portion of head, more densely concentrated on snout and anterior border of eye.Dorsal portion of body densely pigmented in larger specimens.Body with black, midlateral stripe extending from the second humeral spot to caudal-fin base; dark pigmentation present on middle caudal-fin rays.Midlateral body stripe expanded dorsally and ventrally to caudal-fin base, forming small caudal spot.Two humeral spots.Anterior one, conspicuous, vertically elongate with superior portion wider, located over third to four vertical series of scales, extending over two to three horizontal series of scales above lateral line; inferior portion of spot narrow, sometimes with constriction at the junction with the upper portion (one to two scales pigmented), extending over one or two horizontal series of scales below lateral line.Second humeral spot large, evident, not ventrally surpassing lateral line, extending over three horizontal series and two to three vertical series of scales.Region between spots pale.Fins with dispersed dark chromatophores (Fig. 7).
Sexual dimorphism.Males with small, fine and delicate, bony hooks on the anal-and pelvic-fin rays.One bony hook per lepidotrichia, rarely one pair, from the first to seventh anal-fin branched rays; maximum seven hooks per ray.Hooks on the pelvic-fin are distributed in second to fourth branched rays.Gill glands (Burns & Weitzman, 1996) were not found macroscopically on first gill arch in either males or females.
Distribution.Astyanax xiru is known from the rio Jacuí drainage, laguna dos Patos system, and from the upper rio Uruguay drainage, Rio Grande do Sul, and Santa Catarina States (Fig. 9).Additional specimens listed did not differ from the population of the laguna dos Patos system but only specimens this system were included as paratypes in order to maintain type series from a single basin.
Etymology.The specific epithet xiru, from Tupi-Guarani, means an old wise Indian.Word used mainly in the treatment personal in the countryside of Rio Grande do Sul State.

Discussion
The three new species were herein assigned to Astyanax according to the traditional definition of the genus given by Eigenmann (1921Eigenmann ( , 1927)).However, none of the characters used by Eigenmann are unique to the genus along with the large number of species assigned to it, makes a difficult task to understand the boundaries of the genus.
Although it is not the aim of this study to propose hypotheses of relationships of three new species, we can make some assumptions based on the phylogeny of Mirande (2010).Even with several provisional clades that need to be tested in the future, as the own author, this is the most comprehensive phylogenetic analysis in terms of terminal taxa and characters, available so far.
According to Mirande (2010), the subfamily Tetragonopterinae (node 224) is defined by a not exclusive synapomorphy, the presence of two pairs of uroneurals.The three new species have one pair of uroneurals, so would not be included in this subfamily.
The share of absence of a dorsal expansion in the rhinosphenoid and the presence of a tubule with anterior branch running parallel to anterior of maxilla and reaching one third of its length (tubule anastomosed in Astyanax dissensus) places A. xiru, A. procerus, and A. dissensus in the species group of node 201 (see Mirande, 2010: fig. 128).This node have two branched, one named of Hyphessobrycon luetkenii clade, where the A. dissensus could be positioned by presence of posterior extent of ventral process of quadrate falling short posterior margin of sympletic, synapomorphy not exclusive of clade.
The other two species, A. procerus and A. xiru, have the synapomorphies that defined the node 200 (sensu Mirande, 2010): fourth infraorbital approximately square or more developed longitudinally than dorsoventrally, coronomeckelian situated mainly dorsal to Meckel cartilage and 24, or less, branched anal-fin rays.In this same group are the A. paris clade and the node 199 (sensu Mirande, 2010).On the other hand, A. xiru not shares the synapomorphies that defined each of these clades (absence of bony hooks on fin rays and possession of several maxillary teeth (Astyanax paris clade) and ventral margin of horizontal process of anguloarticular perpendicular to laterosensory canal of dentary (node 199 -sensu Mirande, 2010).
Astyanax procerus does not have bony hooks on fins, but otherwise is polymorphic regarding the synapomorphy that involves the process of horizontal anguloarticular.Both species, A. procerus and A. xiru, have only one tooth in the maxillary, a not exclusive synapomorphy that defines Astyanax clade, a branch of the internal node 199 (sensu Mirande, 2010).
Considering the hypothesis of Mirande (2010) we find that the three new species are not placed with members of Tetragonopterinae but in a distinct clade, which are species of Astyanax and other polyphyletic genera.
Along Astyanax species that occur in the rio Uruguay basin and laguna dos Patos and rio Tramandaí systems, A. dissensus, A. ojiara, and one undescribed species (MCP 10413), are the ones with a larger and heptacuspidate tooth in the maxillary.However, A. dissensus differs from undescribed species by the caudal peduncle depth (smaller in A. dissensus) and by the abrupt decrease of the dentary teeth from the fourth tooth (from the fifth tooth in A. dissensus), and from A. ojiara by the head length (smaller in A. dissensus) and by the presence of bony hooks only anal-fin rays of males in A. dissensus (vs.all fins).In the remaining species, or the maxillary is toothless or when presents the teeth are not distally expanded, when compared with the maxillary tooth of the new species, and have usually three to five cusps.
greatest body depth anterior to dorsal-fin origin.Dorsal profile of head straight or slightly convex from posterior nostril to tip of supraoccipital spine.Dorsal body profile convex from tip of supraoccipital spine to base of last dorsal-fin ray; straight from latter point to adipose fin origin.Ventral profile of body convex from vertical through posterior nostril to pelvic-fin origin, nearly straight to anal-fin origin, and posterodorsally slanted along anal-fin base.Caudal peduncle elongate, nearly straight to slightly concave in the dorsal and ventral margins.Snout rounded from margin of upper lip to vertical through anterior nostrils.Head somewhat pointed anteriorly in lateral profile.Mouth terminal, jaw isognathous, Maxilla extending posteriorly to vertical through anterior margin of orbit, slightly curved.

Fig. 6 .
Fig. 6.Map of southern Brazil and Uruguay, showing the distribution of the material examined of Astyanax procerus.Some symbols represent more than on lot or locality.Black circle = type locality.

Fig. 9 .
Fig. 9. Map of southern Brazil and Uruguay, showing the distribution of the material examined of Astyanax xiru.Some symbols represent more than on lot or locality.Black circle = type locality.