First record of Phallotorynus victoriae Oliveros , 1983 ( Cyprinodontiformes , Poeciliidae ) for Uruguay river basin and Rio Grande do Sul , southern Brazil

The first occurrence of Phallotorynus victoriae is reported from the Uruguay river basin associated with the grasslands of the Pampa Biome, southern Brazil. The record includes only one specimen from a tributary to Ibicuí River located in the municipality of Uruguaiana, Rio Grande do Sul state.


Methods
The specimen of Phallotorynus victoriae (Fig. 1) was collected in Ipané stream, a tributary of Ibicuí, 10 km from road BR 472 under the São João Arregui bridge (29°29′53″ S, 056°35′43″ W, 61 m above sea level, Fig. 2), located in the municipality of Uruguaiana, Rio Grande do Sul, Brazil.The specimen was fixed in 10% formalin, later transferred to 70% alcohol, and deposited at the collection of fishes of Laboratory of Ichthyology of Universidade Federal do Rio Grande do Sul (UFRGS) under the following voucher number: UFRGS 23645, 1 specimen, male, 15.3 mm standard length (SL).Measurements follow Lucinda et al. (2005) and were made with a digital caliper reading to the nearest 0.1 mm.Distribution map was made with the software Quantum GIS v. 1.8.0 (Scherman et al. 2005).

Discussion
In poecilids, the gonopodium plays a very important role in the copulation process and used as a diagnostic feature within the family (Chambers 1987, Chambers 1990, Lucinda et al. 2005, Lucinda and Graça 2015).According to Chambers (1987), the length of the gonopodium relative to the standard length varies markedly amongst the genera of Poeciliidae, forming 2 main groups: the first group formed by species with longer gonopodia (50-70% of SL).The gonopodium base is inserted just posterior to a vertical from the pectoral fin base (e.g.Poeciliopsis, Phallichthys, Cnesterodon and Heterandria).The second group are species with short gonopodia (33% or less of SL).The gonopodium base is anteriorly situated, almost between the pelvic fins at or about a vertical drawn from the dorsal fin origin (e.g.Alfaro, Poecilia, Priapella, Belonesox and Xiphophorus).Phallotorynus may be categorized in the second group, with length of the gonopodium of 36% of SL, which is lower than that recorded for the first group.
Morphometric analysis of the specimen (Table 1) shows a lower body depth than that recorded by Lucinda et al. (2005), showing that this species has a greater range of variation in this measurement, as recorded for Phallotorynus fasciolatus (23.6-32.1% of SL).
All Phallotorynus species have not yet been assessed for the IUCN Red List, but in Brazil, P. fasciolatus and P. jucundus are considered Endangered (ICMBio 2016).Phallotorynus victoriae is known from several places (Lucinda et al. 2005) and has an Extent of Occurrence exceeding 20,0000 km 2 .Although this species seems rare and is known only in habitats with intact riparian vegetation, based on its wide distribution along the Paraná and  Uruguay rivers, this species can be classified as Least Concern using IUCN criteria (IUCN 2017).Finally, this record suggests that although the Uruguay river basin is relatively well known, there are still unexplored habitats, where there may be species not yet reported, such as the recently reported Ctenobrycon cf.alleni (Eigenmann & McAtee, 1907), Serrapinnus kriegi (Schindler, 1937), and Laetacara dorsigera (Heckel, 1840), which were known from Paraguay and Paraná river basins (Bertaco et al. 2016).Therefore, this study is the first record of the genus Phallotorynus and extends the distribution of P. victoriae in the Uruguay river basin and the state of Rio Grande do Sul.

Figure 2 .
Figure 2. Previous known distribution of Phallotorynus victoriae including Paraná and Paraguay river basins (black circles; red star is the type locality), and the new record (yellow circle) from Uruguay river basin, municipality of Uruguaiana, Rio Grande do Sul, Brazil.Previous distribution records from Lucinda et al. (2005).

Figure 1 .
Figure 1.Male of Phallotorynus victoriae, UFRGS 23645, 15.3 mm SL, captured in Uruguay river basin, Rio Grande do Sul, Brazil.Left to right image for better visualization of the gonopodium.Scale bar = 2 mm.
Phallotorynushas not been recorded from the Rio Grande do Sul state to date and neither from the Uruguay river basin.Thus, the first record of Phallotorynus victoriae from Rio Grande do Sul state, southern Brazil and from the Uruguay river basin is reported here, which suggests a broader distribution for this species.

Table 1 .
Morphometric characters of males of Phallotorynus victoriae.Measurements 1-10 are percent of standard length and measurements 11-13 are percent of head length.