Lateral Series Research Articles

Trichomycterus anhanga, a new species of miniature catfish related to T. hasemani and T. johnsoni (Siluriformes: Trichomycteridae) from the Amazon basin, Brazil

Trichomycterus anhanga is described from the Amazon basin, northern Brazil. The species is diagnosed by the latero-sensory system which is restricted to LL1 and LL2, the pectoral fin with two branched rays, the absence of pelvic fins and girdle, the reduced jaws and pharyngeal dentition, the presence of six to seven interopercular odontodes, the absence of a lateral series of spots, the presence of a small dark spot on the ventral surface of the mandibular symphysis, the narrow comma-shaped palatine, the absence of procurrent rays anterior to the dorsal and anal fins, the position of insertion of the first dorsal-fin pterygiophore and the presence of a single pair of pleural ribs. Trichomycterus anhanga shares with T. hasemani and T. johnsoni a wide cranial fontanel which occupies most of the skull roof. Miniaturization as well as synapomorphies for the T. hasemani group are discussed.

Discovery of the freshwater genus Sicyopus (Teleostei: Gobioidei: Sicydiinae) in Madagascar, with a description of a new species and comments on regional dispersal

In the Indo-Pacific area, insular rivers are mainly colonized by gobiids of the Sicydiinae subfamily. These species spawn in freshwater, where the free embryos drift downstream to the sea before returning to rivers to reproduce; they are amphidromous. These gobies are the greatest contributors to the fish diversity and have the highest levels of endemism. Among the nine known genera of Sicydiinae, only two have been found in the West Indian Ocean, and only one (Sicyopterus) is known from Madagascar. Recently, two surveys discovered a new species in the genus Sicyopus. Sicyopus lord sp. nov. differs from other species by a combination of characters that includes a particular colour pattern, similar in both sexes; more scales than its congeners in lateral series (35–43), transverse back series (12–18) and a shorter caudal fin length in male fish. This paper describes the new species and discusses the presence of this genus in Madagascar.

Intergeneric phylogenetic relationships in catfishes of the Loricariinae (Siluriformes: Loricariidae), with the description of Fonchiiloricaria nanodon: a new genus and species from Peru

Recent investigations in the upper Río Huallaga in Peru revealed the presence of an intriguing species of the Loricariinae. To characterize and place this species within the evolutionary tree of the subfamily, a molecular phylogeny of this group was inferred based on the 12S and 16S mitochondrial genes and the nuclear gene F-reticulon4. The phylogeny indicated that this distinctive species was a member of the subtribe Loricariina. Given its phylogenetic placement, and its unusual morphology, this species is described as a new genus and new species of Loricariinae: Fonchiiloricaria nanodon. This new taxon is diagnosed by usually possessing one to three premaxillary teeth that are greatly reduced; lips with globular papillae on the surface; the distal margin of lower lip bearing short, triangular filaments; the premaxilla greatly reduced; the abdomen completely covered by plates, with the plates between lateral abdominal plates small and rhombic; a caudal fin with 14 rays; the orbital notch absent; five lateral series of plates; dorsal-fin spinelet absent; preanal plate present, large and solid, and of irregular, polygonal shape, the caudal peduncle becoming more compressed posteriorly for the last seven to 10 plates.

Rivulus albae, a new species of killifish (Teleostei: Cyprinodontiformes: Rivulidae) from northeastern Brazil

Rivulus albae, new species, from northeastern Brazil, is described. It is a member of the subgenus Melanorivulus and distinguished from all other species of this assemblage having brown oblique bars on the entire flank often form chevron-like marks with a posterior vertex and differs from R. decoratus by having less scales on lateral series and more branchiostegal and anal fin rays.

A new genus of fungus-inhabiting blattisociid mites (Acari: Mesostigmata: Phytoseioidea) from Middle America, with a key to genera and subgenera of the subfamily Blattisociinae

The genus Fungiseius gen. nov. is described, based on adults of two newly described species. These rather short-legged mites, with their second pair of legs markedly thickened, have been collected only from bracket fungi. The more generalized form, F. clavulisetis gen. et sp. nov., is based on female specimens from Chiapas Province, southern Mexico. The more derivative form, F. armatus gen. et sp. nov., is based on females and males from several samples of bracket fungi in lowland tropical rainforest of Costa Rica, where they coexist with a remarkable variety of other blattisociine mites. Notable morphological attributes peculiar to adults of this genus include the dorsal shield having a delineated lateral rim that bears a row of setae of the lateral or marginal series, legs II greatly thickened, with enlarged, claw-like setae on the dorsolateral face of the tarsus, and deep furrows postgenitally on females and postanally on males and females. Comparisons are made with fungus-inhabiting mites of the genus Hoploseius, whose adults also have the second pair of legs thickened. A revised key to the world genera and subgenera of the subfamily Blattisociinae is presented; the genus Orthadenella Athias-Henriot is excluded, and placed in the ascoid family Melicharidae. The subgenera Borinquolaelaps Fox, Crinidens Karg, and Cuspiacus Christian & Karg, sensu Christian & Karg 2006 are treated as new synonyms of the subgenus Lasioseius Berlese.

A new species of Bryconops (Teleostei: Characidae) from the rio Madeira basin, Northern Brazil

A new species of Bryconops is described from a tributary to the rio Madeira in the Amazon basin, State of Rondônia, Brazil. Bryconops piracolina belongs to the subgenus Bryconops by having no teeth or rarely one tooth in the maxilla, and a naked area on cheek between the second and third infraorbitals. The new species is distinguished from all species of this subgenus by the presence of a large black blotch on dorsal-fin base. Furthermore, it is distinguished from all congeners, except B. inpai, by possessing the adipose fin entirely black. It differs from B. inpai by the lack of humeral spots. It further differs from all species of the subgenus Bryconops, except B. caudomaculatus, by having the last scales of the longitudinal series of scales that bears the lateral line series not pored beyond the end of the hypural plate, and differs from B. caudomaculatus by the smaller number of pored lateral line scales (31-36, mean 34.6, vs. 37-43, mean = 40.6, respectively).

Redescription of Astyanax erythropterus (Holmberg, 1891) (Teleostei: Characiformes: Characidae) from La Plata basin in Argentina

Astyanax erythropterus (Holmberg, 1891) originally described on the basis of one juvenile, is redescribed herein based on juveniles and adults from the type-localiy. The species differs from its congeners by the combination of 11-13 transverse rows scales above lateral line and 8-10 rows below lateral line; 49-54 perforated scales in the lateral series; iii-v,38-42 anal-fin rays, and dorsal, anal and caudal fins vermilion red in juveniles. The vermilion red coloration of unpaired fins in juveniles of Astyanax is only known in A. correntinus.

Technique for Targeting Arteriovenous Malformations Using Frameless Image-Guided Robotic Radiosurgery

To integrate three-dimensional (3D) digital rotation angiography (DRA) and two-dimensional (2D) digital subtraction angiography (DSA) imaging into a targeting methodology enabling comprehensive image-guided robotic radiosurgery of arteriovenous malformations (AVMs). DRA geometric integrity was evaluated by imaging a phantom with embedded markers. Dedicated DSA acquisition modes with preset C-arm positions were configured. The geometric reproducibility of the presets was determined, and its impact on localization accuracy was evaluated. An imaging protocol composed of anterior-posterior and lateral DSA series in combination with a DRA run without couch displacement between acquisitions was introduced. Software was developed for registration of DSA and DRA (2D-3D) images to correct for: (a) small misalignments of the C-arm with respect to the estimated geometry of the set positions and (b) potential patient motion between image series. Within the software, correlated navigation of registered DRA and DSA images was incorporated to localize AVMs within a 3D image coordinate space. Subsequent treatment planning and delivery followed a standard image-guided robotic radiosurgery process. DRA spatial distortions were typically smaller than 0.3 mm throughout a 145-mm × 145-mm × 145-mm volume. With 2D-3D image registration, localization uncertainties resulting from the achievable reproducibility of the C-arm set positions could be reduced to about 0.2 mm. Overall system-related localization uncertainty within the DRA coordinate space was 0.4 mm. Image-guided frameless robotic radiosurgical treatments with this technique were initiated. The integration of DRA and DSA into the process of nidus localization increases the confidence with which radiosurgical ablation of AVMs can be performed when using only an image-guided technique. Such an approach can increase patient comfort, decrease time pressure on clinical and technical staff, and possibly reduce the number of cerebral angiograms needed for a particular patient.

Redescription of Astyanax stenohalinus Messner, 1962 (Characiformes: Characidae), a poorly known species from Argentina and Uruguay

Astyanax stenohalinus Messner, 1962 is redescribed based on type material and new specimens collected in many localities of Argentina and Uruguay. This species is distinguished by a combination of the following characters: possession of hooks in all fins of males, teeth not expanded distally, two or three maxillary teeth, 37–39 perforated scales in the lateral series, 25–30 branched anal-fin rays, and anal-fin origin located before a vertical through last dorsal-fin ray insertions.

Complications and radiographic correction in adult scoliosis following combined transpsoas extreme lateral interbody fusion and posterior pedicle screw instrumentation

The authors recently used a combined approach of minimally invasive transpsoas extreme lateral interbody fusion (XLIF) and open posterior segmental pedicle screw instrumentation with transforaminal lumbar interbody fusion (TLIF) for the correction of coronal deformity. The complications and radiographic outcomes were compared with a posterior-only approach for scoliosis correction. The authors retrospectively reviewed all deformity cases that were surgically corrected at the University of Pittsburgh Medical Center Presbyterian Hospital between June 2007 and August 2009. Eight patients underwent combined transpsoas and posterior approaches for adult degenerative thoracolumbar scoliosis. The comparison group consisted of 4 adult patients who underwent a posterior-only scoliosis correction. Data on intra- and postoperative complications were collected. The pre- and postoperative posterior-anterior and lateral scoliosis series radiographic films were reviewed, and comparisons were made for coronal deformity, apical vertebral translation (AVT), and lumbar lordosis. Clinical outcomes were evaluated by comparing pre- and postoperative visual analog scale scores. The median preoperative coronal Cobb angle in the combined approach was 38.5 degrees (range 18-80 degrees). Following surgery, the median Cobb angle was 10 degrees (p < 0.0001). The mean preoperative AVT was 3.6 cm, improving to 1.8 cm postoperatively (p = 0.031). The mean preoperative lumbar lordosis in this group was 47.3 degrees, and the mean postoperative lordosis was 40.4 degrees. Compared with posterior-only deformity corrections, the mean values for curve correction were higher for the combined approach than for the posterior-only approach. Conversely, the mean AVT correction was higher in the posterior-only group. One patient in the posterior-only group required revision of the instrumentation. One patient who underwent the transpsoas XLIF approach suffered an intraoperative bowel injury necessitating laparotomy and segmental bowel resection; this patient later underwent an uneventful posterior-only correction of her scoliotic deformity. Two patients (25%) in the XLIF group sustained motor radiculopathies, and 6 of 8 patients (75%) experienced postoperative thigh paresthesias or dysesthesias. Motor radiculopathy resolved in 1 patient, but persisted 3 months postsurgery in the other. Sensory symptoms persisted in 5 of 6 patients at the most recent follow-up evaluation. The mean clinical follow-up time was 10.5 months for the XLIF group and 11.5 months for the posterior-only group. The mean visual analog scale score decreased from 8.8 to 3.5 in the XLIF group, and it decreased from 9.5 to 4 in the posterior-only group. Radiographic outcomes such as the Cobb angle and AVT were significantly improved in patients who underwent a combined transpsoas and posterior approach. Lumbar lordosis was maintained in all patients undergoing the combined approach. The combination of XLIF and TLIF/posterior segmental instrumentation techniques may lead to less blood loss and to radiographic outcomes that are comparable to traditional posterior-only approaches. However, the surgical technique carries significant risks that require further evaluation and proper informed consent.

A new species of Microlepidogaster (Siluriformes: Loricariidae: Hypoptopomatinae) from the upper rio Paraná basin, Brazil

Microlepidogaster longicolla, new species, is described from the rio São João of the upper rio Paraná basin near Brasília, in central Brazil. The new species differs from M. perforatus, the only other species in this genus, by having a continuous lateral line, median lateral plate series reaching, rather than falling short of, the end of the caudal peduncle, a shorter pectoral-fin spine (13.4-16.2 vs. 18.2-21.0% standard length), a smaller interorbital distance (38.9-43.1 vs. 47.7-53.3% head length), and more numerous dentary teeth (16-29 vs. 12-15), in addition to several osteological features. Microlepidogaster longicolla shows a remarkable suite of secondary sexually dimorphic characters, involving the presence of a conical urogenital papilla in males, the presence of a fleshy flap along the dorsal margin of first thickened pelvic-fin ray of males, longer pelvic fin in males, and a more strongly arched first pelvic-fin ray in females.

New species of Moenkhausia Eigenmann (Characiformes: Characidae) from Rio Xingu and Rio Tapajós basins, Brazil, with comments on a putative case of polymorphic Batesian mimicry

A new species of Moenkhausia is described from Rio Xingu and Rio Tapajós basins, Brazil. The new species is distinguished from its congeners, except from Moenkhausia moisae, by having more scales in the lateral series, 43-47 (v. 23-41 in the remaining congeners). The new species is distinguished from M. moisae by its colour pattern, which consists of a dark midlateral stripe, and an asymmetrical caudal blotch (inconspicuous or faded in specimens from the Rio Arinos) continuous with the midlateral stripe (v. narrow dark midlateral line and conspicuous, regularly rounded and symmetrical blotch not continuous with the midlateral line). The new species is putatively assumed to be mimetic to Jupiaba apenima, in the Rio Xingu and Rio Teles Pires drainages, and to Jupiaba yarina in the Rio Arinos. The two species of Jupiaba are sympatric and remarkably similar in size, general external morphology and colouration to the new species. A small difference occurs in the colouration between the two species of Jupiaba and is also observed in the two respectively sympatric morphotypes of the new species of Moenkhausia. The occurrence of polymorphic Batesian mimicry is therefore discussed for neotropical freshwater fishes.

Localization Technique for Frameless Image-guided Robotic Radiosurgery of Arteriovenous Malformations

Purpose/Objective(s): To integrate three-dimensional digital rotation angiography (3D DRA) and two-dimensional digital subtraction angiography (2D DSA) imaging in a localization technique that enables frameless image-guided robotic radiosurgery of arteriovenous malformations (AVMs). Materials/Methods: The geometric integrity of the 3D DRA images generated by a clinical flat panel detector Carm neuroangiography system was evaluated and quantified by imaging a phantom with embedded markers. Dedicated DSA acquisition modes with preset C-arm positions were configured. The geometric reproducibility of the C-arm presets was investigated and its impact on localization accuracy evaluated. An imaging protocol comprising anterior-posterior (AP) and lateral (LAT) 2D DSA series combined with 3D DRA without couch displacement between acquisitions was introduced. A software environment (Angio-Localize) was developed for 2D-3D registration of the 3D DRA and the 2D DSA images to correct for: (i) small misalignments of the C-arm with respect to the assumed geometry of the preset imaging positions and (ii) potential patient motion between the image series. Within the same environment, correlated navigation of the registered 3D DRA and DSA images was incorporated so that an AVM could be localized and contoured within the 3D DRA coordinate space. AVM contours were then transferred onto a planning CT by CT-3D DRA registration. The subsequent treatment planning and delivery followed the standard process for frameless image-guided robotic radiosurgery treatments. Results: The magnitude of the 3D DRA spatial distortions was smaller than 0.3 mm throughout a 140 mm x 140 mm x 140 mm field of view. Localization uncertainties resulting from the achievable reproducibility of the C-arm preset positions were reduced to less than 0.2 mm with 3D-2D image registration. Overall system-related localization uncertainty within the DRA coordinate space was estimated to be 0.4-0.5 mm. The localization protocol was implemented clinically and image-guided frameless robotic radiosurgical treatments with this technique were initiated. Conclusions:The integration of three-dimensional digital rotation angiography (3D DRA) and two-dimensional digital subtraction angiography (2D DSA) imaging in a localization technique that enables frameless image-guided robotic radiosurgery of arteriovenous malformations (AVMs) is possible. Clinically it is expected to result in increased patient comfort; reduced time pressure on clinical and technical staff, and possible reduction of the number of neuro-angiography procedures for particular patient.

Periophthalmus variabilis(Teleostei: Gobiidae: Oxudercinae), a Valid Species of Mudskipper, and a Re-diagnosis ofPeriophthalmus novemradiatus

The current concept of Periophthalmus novemradiatus (Hamilton, 1822) includes two species. Procurement of fresh material and examination of extant type specimens revealed that P. novemradiatus differs from P. variabilis Eggert, 1935, primarily in the number of anal fin rays (I, 12 or 13 vs. I, 10-12); the lateral scale series (62-67 vs. 48-60); the extent of fusion of the pelvic fins (56.0-90.0% vs. 32.0-48.8%); and the patterns of the first and second dorsal fins.

Potential of quartz OSL dating on moraine deposits from eastern Tibetan Plateau using SAR protocol

Optically stimulated luminescence (OSL) dating methods have been widely applied in Quaternary glaciology. However, glacigenic deposits are considered in general as problematic for OSL dating, mainly because they are transported shorter distances prior to burial and are usually partially bleached. Thus, most researchers choose glaciofluvial and glaciolacustrine sediments (with relatively longer transportation times) for OSL dating when constraining the age of glaciation. In this study, four samples were collected from a lateral moraine series at Zhuqing Village, northern margin of Queer Shan Mountain, eastern Tibetan Plateau, in order to investigate the applicability of OSL dating for morainic deposits. Quartz grains (38–63 μm) were extracted and measured using single aliquot regenerative-dose (SAR) protocol. Internal checks and dose recovery test show that the SAR protocol is appropriate for equivalent dose (D e) determination. The effect of thermal transfer is small for all samples and the recycling ratio for each individual sample is close to unity. The symmetry in the D e distributions indicates that quartz grains were well-bleached prior to burial. OSL ages show good agreement with geomorphological and field investigations, and are also concordant with an independent ESR age. It is concluded that: (a) the morainic deposits in Zhuqing were well-bleached and suitable for OSL dating; (b) SAR protocol can be applied to morainic deposits for samples under study.

Sedimentary formations of the Verkhoyansk belt and settings of their accumulation

Based on the summarization of original field investigations, analysis of numerous medium-scale geological maps, and literature data, sedimentary formations of the Verkhoyansk fold-thrust belt and its eastern framing of terranes, as well as their lateral series and accumulation settings are considered.

Assessing species validity of Mugil platanus Günther, 1880 in relation to Mugil cephalus Linnaeus, 1758 (Actinopterygii)

Conservative morphological characters make identification of mullet species difficult. As a consequence, cosmopolitan distribution of Mugil cephalus is currently under discussion. In order to clarify the controversy regarding the taxonomic status of the southern Atlantic American mullet M. platanus, in relation to Mugil cephalus, a comprehensive analysis is presented using sequences of the mitochondrial gene cytochrome b, landmark‐based morphometry and meristic data. The interlandmark distances showed differentiation between individuals of M. platanus and M. cephalus analyzed. Variables, representing the height at different levels of the longitudinal axis of the body, exposed that M. platanus has more robust middle and caudal segments of the body, in a lateral view, with respect to M. cephalus. Transversal series scales have not been useful for the identification of species. Lateral series scales seem to be useful to differentiate species, but taking into account that range showed an overlapped gradual variation. Genetic distance obtained between species shows a typical intrageneric level comparison. Two clear phylogroups have been detected indicating a high degree of genetic isolation between both species. Recognition of M. platanus as valid allopatric species is suggested.

Typhlocharis Dieck, 1869 (Coleoptera: Carabidae, Anillini): a new species from the Iberian Peninsula, with notes about its relationships and the evolution of the diecki species group

A new species of the genus Typhlocharis Dieck (Coleoptera: Carabidae, Anillini), T. martini, described from the upper Segura River (province of Albacete, southeast Spain), is included in the diecki group characterised by a series of 4 +3 setae in the lateral umbilical series and a reduced number of preapical and apical dentiform projections of the elytron. A key to the eight species of the diecki species group is included. The relationships of the new taxon and the hypotheses about the evolutionary history of Typhlocharis and the diecki species group are discussed.

Threatened fishes of the world: Girardinichthys viviparus (Bustamante 1837) (Cyprinodontiformes: Goodeidae)

Common name: Mexclapique (Bustamante 1837) or Chapultepec splitfin. Conservation status: Endangered, NOM-059-ECOL-2001 (Diario Oficial 2002); and critically endangered (CRA1ce+2ce+2abc), IUCN (ContrerasBalderas and Almada-Villela 1996). Identification: Maximum SL 65 mm; at present, males reach only 27 mm and females 39 mm. Dorsal fin, 18–26 rays; anal fin, 20–27 rays. Teeth conical. Scales in lateral series, 40–43. Usually 15–18 gill rakers. Trophotaeniae: two long anterior processes and two shorter posterior processes. Dorsal, anal and caudal fins show a black band terminally in adult males.Distribution: Endemic to Basin of Mexico: Lakes Xochimilco, Zumpango, Texcoco and Chapultepec (Alvarez del Villar and Navarro 1957). Abundance: Abundant in artificial pools in Lake Texcoco, scarce in Lakes Xochimilco and Chapultepec, and absent in Lake Zumpango.Habitat and ecology: In Lake Texcoco, it inhabits highly productive saline pools; water hardness (1,549 mg/l), alkalinity (412± 70.21mg/l), conductivity 10,254±444mS/cm, pH7.82± 0.17, well oxygenated and turbid water, water temperature 13–21°C. Reproduction: March to October, viviparous with multiple reproductive cycles, with occasional superfetation. Females reach sexual maturity at 1 year. Fecundity, 15–47 embryos (Diaz-Pardo and Ortiz-Jimenez 1986). Threats: Habitat loss due to urban and industrial development and water extraction (Contreras-Balderas 2005). Wastewater inputs in Xochimilco (including heavy metal and pesticides) elicited early warning biomarkers damage in G. viviparous (Lopez-Lopez et al. 2006). Conservation action: The National Water Commission maintains the species in artificial pools in Texcoco. Xochimilco has been included in the RAMSAR wetlands since 2004 and was Environ Biol Fish (2009) 84:11–12 DOI 10.1007/s10641-008-9380-4

Taxonomic Review of Rineloricaria (Loricariidae: Loricariinae) from the Laguna dos Patos Drainage, Southern Brazil, with the Descriptions of Two New Species and the Recognition of Two Species Groups

The species of Rineloricaria from the Laguna dos Patos drainage are reviewed. Four species are rediagnosed: R. strigilata, R. cadeae, R. microlepidogaster, and R. longicauda, and two new species are described: R. malabarbai and R. baliola. Rineloricaria malabarbai is distinguished from all other Rineloricaria species except R. maquinensis by its unique abdominal pattern, composed of a large naked area with a single preanal complex of plates and one or two small squarish platelets at the base of pelvic-fin spine and connecting the preanal complex to the lateral abdominal plates, and from R. maquinensis it is distinguished by a longer predorsal length, shorter postanal length, longer abdominal length, broader cleithral width, broader body width at anal-fin origin, deeper head, and shorter maxillary barbel. Rineloricaria baliola is distinguished by its unique color pattern composed of dark, wide bands covering most of the distal one-half of all fins, and by its snout with a roundish naked area, generally reaching to anteriormost pore of infraorbital ramus of sensory canal. The species in Rineloricaria are divided in two phenetic groups, based on general background color pattern, distribution of plates on abdomen, head and snout shape, shape of the naked area at tip of snout, number of lateral body series of plates, and presence of the dorsal-fin spinelet. Species illustrations and a taxonomic key for the Laguna dos Patos drainage are provided.Son revisadas las especies de Rineloricaria del sistema de la Laguna dos Patos. Cuatro especies son rediagnosticadas: R. strigilata, R. cadeae, R. microlepidogaster, y R. longicauda; y dos nuevas especies se describen para el sistema: R. malabarbai y R. baliola. Rineloricaria malabarbai se distingue de las otras especies de Rineloricaria, excepto R. maquinensis, por su único patrón de placas abdominales compuesto por un gran área desnuda con un complejo de placas preanales y una o dos pequeñas placas cuadrangulares en la base de la espina de la aleta pélvica, que conectan el complejo preanal a las placas abdominales laterales. De R. maquinensis se distingue por presentar mayor longitud predorsal, menor longitud postanal, mayor longitud abdominal, mayor ancho cleithral, mayor ancho del cuerpo en el origen de la aleta anal, cabeza más baja y barbillas maxilares más cortas. Rineloricaria baliola se distingue por su único patrón de coloración, compuesta de oscuras y amplias barras en todas las aletas, comprendiendo la mitad distal, y por su patrón de placas abdominales. Las especies de Rineloricaria son divididas en dos grupos fenéticos, basados en el patrón de coloración general, cobertura de placas en el abdomen, forma de la cabeza y el hocico, forma del área desnuda del extremo del hocico, número de series de placas laterales del cuerpo y presencia de “spinelet” en la aleta dorsal. Se provee una clave taxonómica e ilustraciones para las especies del sistema de la Laguna dos Patos.