First record of Steindachnerina insculpta ( Fernández-Yépez , 1948 ) ( Characiformes , Curimatidae ) in Argentina

Recent expeditions to northwestern Argentina revealed the presence of an unknown species of Curimatidae for the Bermejo river basin. The morphometric and meristic analyses of these specimens allow us to identify them as Steindachnerina insculpta (Fernández-Yépez, 1948), which is here reported for the first time in Argentina.


Introduction
Curimatidae is a monophyletic family within Characiformes and is supported by synapomorphies related to the branchial apparatus, buccopharyngeal complex, hyoid arch, jaws, palatine arch, and neurocranium (Vari 1989, Dillman et al. 2016), which are associated with specialized food acquisition and processing (Netto-Ferreira and Vari 2011).Vari (1989) proposed the monophyly of Steindachnerina Fowler 1906 on the basis of 4 synapomorphies related to modifications in the first and second infrapharyngobranchials, the ventral process of the third hypobranchial (H3), the basihyal, and associated basihyal tooth-plate.
Currently, Steindachnerina is composed by 24 valid species distributed in a wide geographic range in South America, from Venezuela to Argentina (Netto-Ferreira and Vari 2011).Three species of Steindachnerina have been recorded from Argentina (Mirande and Koerber 2015).Steindachnerina biornata (Braga & Azpelicueta, 1987) and S. brevipinna (Eigenmann & Eigenmann, 1889) inhabit the Uruguay and Paraná rivers, and S. conspersa (Holmberg, 1891) inhabits the Paraguay river basin.The geographic range of S. brevipinna and S. conspersa also includes the Upper Bermejo river basin in northwestern Argentina (Azpelicueta andBraga 1991, Monasterio de Gonzo 2003).
Recent expeditions to northwestern Argentina revealed a distinct curimatid species for the Bermejo river basin.The aim of this contribution is to report the occurrence of Steindachnerina insculpta in the Upper Bermejo river basin, representing the first record of this species in Argentina.

Methods
Morphometric measurements were taken using calipers to nearest 0.1 mm following Vari (1991) and are expressed as percentages of standard length (SL) and head length (HL).Numbers between parentheses after meristic feature indicate the number of specimens with that specific count.Specimens were cleared and stained (C & S) following Taylor and Van Dyke (1985).Vertebral counts were based in a single C & S specimen and considered the fused PUj + U1 as 1 vertebra, while the Weberian apparatus complex was counted as 4 elements.Comparative material is presented in the Appendix.

Results
Our analysis of specimens from 2 localities in the Bermejo river basin (Fig. 1) allowed us to identify them as Steindachnerina insculpta.Identification.Specimens are identified by the presence of multiple lobulated fleshy processes on the roof of the oral cavity (Fig. 2), the lack of a dark spot on the basal portion of the middle dorsal fin (Fig. 3), 41-46 perforated scales on the lateral line series, and the presence of a dark stripe along the midlateral surface of the body.These features were considered by Vari (1991) as useful to distinguish S. insculpta from its congeners.Morphometric measurements of S. insculpta (Fig. 3) from the Bermejo river basin are presented in Table 1.

Discussion
The known distribution range of Steindachnerina insculpta includes the type locality in the Upper Paraná river basin in Brazil, and an additional record in the Upper Paraguay river basin (Vari 1991).Koerber et al. (2017) cited S. insculpta as present in Paraguay, but considered its presence there as doubtful.The new records of S. insculpta in the Bermejo river basin, a tributary to the middle Paraná River, expand the geographic dis-tribution by about 1000 km from the nearest records in the Paraná river basin.No records of this species have been reported from the middle and lower portions of the Paraná river basin, which could be due to the misidentification of Steindachnerina specimens.Steindachnerina insculpta was found syntopically with S. conspersa in the Bermejo River, and with S. brevipinna in the San Francisco River.The lack of a dark spot in the basal portion of the dorsal fin readily differentiates S. insculpta from these species, and additionally, the higher number of perforated scales on the lateral line distinguishes it from S. brevipinna (36-46 vs 33-37).This contribution provides the first records of S. insculpta in Argentine freshwaters, at 2 locations of the Upper Bermejo river basin in the provinces of Salta and Jujuy.

Figure 1 .
Figure 1.Map of northwestern Argentina area.Black rectangle indicates the area of the recorded specimens of Steindachnerina insculpta: San Francisco River (1) and Madrejón El Divisadero (2) in the upper Bermejo River.

Figure 2 .
Figure 2. Multiple lobulate fleshy processes on the roof of the oral cavity, a diagnostic character of Steindachnerina insculpta, CI-FML 7340, 47.7 mm SL, from the San Francisco River, Bermejo river basin.

Table 1 .
Morphometric measurements of Steindachnerina insculpta recorded to the Upper Bermejo river basin, including 10 specimens from CI-FML 7340 and 12 from CI-FML 7336.SD = standard deviation.