Monthly Archives: November 2018

PEIXE DA VEZ: Attonitus ephimeros Vari & Ortega, 2000

Vanessa Meza-Vargas & Dario Faustino-Fuster

Descrita por Vari & Ortega em 2000, tem localidade tipo na quebrada Mapichiriato, tributário do rio Picha na bacia do rio Urubamba na província de La Convención, Cusco, Perú. O gênero pertence à Stevardiinae, membro da tribo Diapomini (Thomaz et al. 2015) e contem três espécies: Attonitus bounites, A. ephimeros e A. irisae. O nome genérico Attonitus refere-se à aparência de “estupefato” ou “atordoado” no momento que foram coletados, com a boca totalmente aberta. No caso do epiteto da espécie A. ephimeros, refere-se a aparência do peixe “agradável ou encantador”. A. ephimeros é endêmico das regiões de pé de monte dos Andes Centrais do Peru.

Link: http://www.sbi.bio.br/images/sbi/boletim-docs/2018/setembro_127_v2.pdf

 

PEIXE DA VEZ: Cynopoecilus notabilis Ferrer, Wingert & Malabarba, 2014

Clayton K. Fukakusa & Junior A. Chuctaya

Cynopoecilus, assim como as espécies de Campellolebias, possuem modificações nos primeiros raios da nadadeira anal dos machos, que possivelmente estão relacionadas à inseminação (Costa et al., 2016). Cynopoecilus é endêmico de uma vasta área do sul do Brasil e nordeste do Uruguai, sendo a maioria das espécies encontradas em formações abertas de pastagem, mas algumas vezes são encontradas em poças nas bordas de florestas costeiras. Cynopoecilus notabilis é uma exceção, pois habita poças rasas dentro de densa floresta estacional semidecidual (Ferrer et al., 2014; Costa, 2016).

link: http://www.sbi.bio.br/images/sbi/boletim-docs/2018/setembro_127_v2.pdf

PEIXE DA VEZ: Rineloricaria parva (Boulenger, 1895)

Alessandra Soares , Tiago P. Carvalho & Luiz R. Malabarba

Rineloricaria parva é uma espécie de cascudo da família Loricariidae e integrante de uns dos gêneros mais diversos nesta família (Vera-Alcaraz et al., 2012; Covain et al., 2016). Segundo as relações filogenéticas apresentadas por Covain et al. (2016), R. parva é grupo irmão de um grande grupo do gênero Rineloricaria com espécies distribuídas no sudeste da América da Sul.

Link: http://www.sbi.bio.br/images/sbi/boletim-docs/2018/junho_126.pdf

Inventário ictiológico da bacia do rio Forqueta com ênfase na região do Perau de Janeiro, Arvorezinha, RS

Juliano Ferrer, Mateus Camana, Cristina Mariana Jacobi, Lara Brasil de Souza, Exequiel Oscar Furlan, João Vítor Vigde Duz, Eduardo Rufino de Senna Gastal, Ricardo Ribeiro Nunes & Tiago P. Carvalho.

Adiversidade de peixes encontrada na América do Sul atinge números impressionantes: em torno de 5.160 espécies descritas de água doce agrupadas em 69 famílias e 20 ordens com estimativas apontando para uma riqueza final entre 8.000 a 9.000 espécies (Reis et al., 2016). As drenagens do Estado do Rio Grande  do  Sul  (RS),  sistemas  da  laguna  dos  Patos  e  rio  Tramandaí  e  bacia  do  rio  Uruguai,  são  bem  inventariadas em termos de ictiofauna contendo 422 espécies  (Bertaco  et  al.,  2016),  incluindo  aquelas  a  espera  de  descrição  formal.  Segundo  estes  mesmos  autores,  o  número  de  espécies  de  peixes  descritas  nos últimos dez anos para o Neotrópico cresceu 20% enquanto que no RS o acréscimo é de 28%, o que denota um “aceleramento” no conhecimento de sua ictiofauna em comparação a outras regiões. Mesmo assim, são notáveis algumas áreas pouco exploradas no  Estado,  a  maioria  delas  situadas  em  regiões  de  cabeceiras.

Artigo completo:

Link: http://www.sbi.bio.br/images/sbi/boletim-docs/2018/junho_126.pdf

Figura 2. Equipe de ictiofauna durante amostragem na região do Perau de Janeiro, Arvorezinha (RS). Da esquerda para direita: Exequiel O. Furlan, Juliano Ferrer, Lara B. de Souza, Cristina M. Jacobi e Ricardo R. Nunes (em pé); Tiago P. Carvalho e Mateus Camana (agachados).

Diet and body shape among populations of Bryconamericus iheringii (Otophysi: Characidae) across the Campos Sulinos ecosystem

Érika Endo Kokubun, Karine Orlandi Bonato, Edward D. Burress, and Clarice Bernhardt Fialho

ABSTRACT

Alterations in natural landscapes, mainly caused by anthropic pressures, have been threatening the world’s biomes, including aquatic environments and its biota. This study describes the diet of Bryconamericus iheringii, and how its body shape relates to environmental variables in populations of 22 streams. A wide array of food items were found, mainly composed of allochthonous plants (50.5%) and autochthonous invertebrates (25.2%). Even though food items remained almost the same, the predominant food group significantly differed among streams, mainly in relation to environmental characteristics. There was variation in body shape primarily associated with body depth and length of the pre-dorsal region; however, these differences did not correspond with streams. PLS-CA analyses indicated that environmental characteristics, such as substrate type, percentage of marginal vegetation have some influence over food items availability but not on body shape. This may be because B. iheringii is a non-specialist species capable of prey switching based on availability due to an intermediate body shape suited for generalist feeding habits.

link: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1679-62252018000400202&lng=en&nrm=iso&tlng=en

Fig. 3 Relative warps (RW) of body shapes among 22 populations of Bryconamericus iheringii: Alegrete (AL), Jaguarão (JG), Santo Antônio das Missões (SM), São Gabriel (SG), Santiago (ST), São Pedro do Sul (SS), Soledade (SL), Quaraí (QR), Santana da Boa Vista (SV) and Lavras do Sul (LV). Warp transformation grids depict the body shapes associated with the extremes of each axis.

Life history characteristics and recruitment of fish under the effect of different hydrological regimes in a tropical floodplain

Karina Keyla Tondato, Yzel Rondon Súarez, Lúcia Aparecida de Fátima Mateus, Wagner Vicentin, and Clarice Bernhardt Fialho

Abstract

With the aim to analyze intra- and interspecific variation in the life history characteristics and recruitment pattern of six fish species, samples were conducted in two different hydrological regime areas of Pantanal (synchronous/Norther and asynchronous/Southern regions – high temperatures and rainfalls are and are not coincident with the flooding period, respectively). In both regions, fish were sampled using sieve net and dragnet along the river and marginal lakes. In the synchronous regime (Cuiabá River), the combined data collected between the years 2005 and 2010 were utilized. In the asynchronous regime (Paraguay River), the collections were made between 2009 and 2011. Length frequency data were used in the FISAT program to estimate the parameters. Four species, in the synchronous regime, reached trend to longer values for the asymptotic length values (L∞) and trend to lower values in growth taxa (k) and mortality (Z), but the outcomes did not demonstrate significant intraspecific variation for L∞and Z by length classes between the hydrologic regimes (except for Moenkhausia dichroura). The recruitment pattern did not show intra- and interspecific variation between the hydrological regimes, with long period of recruitment and greater pulse for all species between June and August. Thus, the correlation of species recruitment with river level in the asynchronous regime follows the flood pulse concept, where the flooding pulse is the main driving force for production of animal and plant biomass. In contrast, the pattern of recruitment in the synchronous regime follows the hypothesis of the low flow recruitment, where the recruitment is not influenced by flooding, despite the period of high temperature and rainfall being coincident with the period of flooding.

Link: https://link.springer.com/article/10.1007/s10641-018-0784-5

Fig. 3 Temporal variation of recruitment (%) of six species of small fish and the historical level of the Cuiabá Rivers (Synchronous regime) and Paraguay (Asynchronous regime) in the Pantanal, Brazil

Fish fauna in forested and rural streams from an ecoregion of high endemism, lower Iguaçu River basin, Brazil

Rosilene Luciana Delariva, Mayara Pereira Neves, Crislei Larentis, Bruna Caroline Kotz Kliemann, Mara Cristina Baldasso, and Luciano Lazzarini Wolff

ABSTRACT

The fish fauna of eight streams with different land uses of their watersheds (forested and rural areas) in the lower Iguaçu River basin was inventoried, in order to evaluate the composition and species richness. The fishes were sampled quarterly from May 2015 to February 2016, using the electrofishing technique. In total, 4,239 individuals were captured, belonging to six orders, 11 families and 26 species. The orders Siluriformes and Characiformes, and the families Characidae and Trichomycteridae were the most specious. Of the total species sampled, 65% were endemic to the Iguaçu River basin, four are not described and four are non-native. As expected to the Iguaçu River basin, the inventoried fauna revealed low richness and high endemism, however was highly nested within the species composition reported for main channel of Iguaçu River and their larger tributaries. The species recorded here corresponded to a subset of 24.5% of the 106 species documented for the basin. The streams presented different faunas, with only two species (Astyanax bifasciatus and Trichomycterus stawiarski) common to both forested and rural streams. In addition, higher species richness was recorded in streams inserted in conservation units. The presence of non-native species was more frequent in rural streams. These results highlight the importance of the preservation of forested areas in the watersheds of lower Iguaçu, which presents a peculiar fish fauna, along with several threats to biodiversity such as habitat loss by intensive agriculture use.

link: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1676-06032018000300304

Is resource partitioning the key? The role of intra‐interspecific variation in coexistence among five small endemic fish species (Characidae) in subtropical rivers

Mayara P. Neves, Jislaine C. Da Silva, Dirceu Baumgartner, Gilmar Baumgartner, Rosilene L. Delariva

Abstract

This study focused on intra and interspecific variations in the diet of small species in the Pelotas River, upper Uruguay River ecoregion. We tested the hypothesis that five small characids coexist via resource partitioning. Samplings were performed quarterly between August 2013 and May 2014 at 14 sites in the Pelotas River basin, using gillnets of different mesh sizes, seines, cast nets and electrofishing. In this study, the contents of 1,253 stomachs were analysed from Astyanax dissensus, A. paris, A. saguazu, A. xiru and Bryconamericus patriciae. The main food resources consumed were aquatic insects, leaves, seeds and detritus. There were significant seasonal intra and interspecific variations in the use of food resources by the five species. Permutational analysis of multivariate dispersions results indicated significant differences in individual intraspecific variability between the sampled periods, with the highest values found in November and February because of an increase in allochthonous resources (leaves and seeds). Besides this, significant differences in the proportions of consumption of allochthonous and autochthonous were observed. The trophic niche breadth was significantly different among the species, such that in August, the species had narrower niche breadths. In the other periods, the highest niche breadth values were due to an increase in the consumption of allochthonous items. Diet overlap was low (< 0.4) between 62% of the species pairs. The small characid species showed pronounced changes in resource use and intra and interspecific variations indicating resource partitioning. These factors appear to be essential in species interactions and for coexistence.

link : https://onlinelibrary.wiley.com/doi/full/10.1111/jfb.13662

FIGURE 3 Ordination of dietary data of individuals (using the first and second axes of principal components analysis, PCoA) of (a) Astyanax dissensus; (b) A. paris; (c) A. saguazu; (d) A. xiru and (e) Bryconamericus patriciae in August ( ), November (), February ( ) and May ( ), between 2013 and 2014, in the Pelotas River basin, in the upper Uruguay ecoregion. [for mean distance from the centroid (D), F-statistics and P-values, see Table III.

Do environmental variables predict the trophic structure of fish fauna in a subtropical river (Uruguay River Ecoregion)?

Mayara P. Neves , Dirceu Baumgartner , Gilmar Baumgartner, and Rosilene L. Delariva 

Abstract

Trophic interactions represent the routes through which energy flows upwards within ecosystems and the understanding of such structuring under varying environmental conditions is still challenging. Here we test the hypothesis that differences in environmental variables act as environmental filters on the composition and trophic structure of local the fish fauna of a subtropical mountain river. We predict that differences in the trophic structure of the fish fauna occur along the river continuum. Main environmental parameters have been measured and fishes were sampled quarterly between August 2013 and May 2014 at six sampling sites in the main channel of the Pelotas River, Upper Uruguay ecoregion. We collected 3848 individuals belonging to 38 species, 4 orders and 11 families. The most (82.1%) consisted of small- and medium-sized individuals. The species were classified into eight trophic guilds: aquatic insectivorous, carnivorous, detritivorous, detritivorous/aquatic insectivorous, herbivorous, iliophagous, omnivorous and piscivorous. In general, herbivorous and piscivorous guilds were the most representative in both number and biomass. Significant differences detected by Permanova were for richness, numerical abundance and biomass between all the sites sampled. Relationships between the environmental variables and the composition of trophic guilds were observed along the longitudinal gradient by RLQ and fourth-corner analyses. The abundance of guilds omnivorous, aquatic insectivorous and herbivorous increases with higher values of chlorophyll-a and vegetation cover, especially characterizing the upstream sites (S1, S2 and S3). On the other hand, the abundance of the iliophagous, detritivorous/insectivorous and piscivorous guilds increases with greater values of width, temperature, inorganic phosphorus and total solids, a fact observed in downstream sites (S4, S5 and S6). Thus, it was possible to identify a clear variation in the trophic structure of the fish fauna along the Pelotas River (upstream-downstream), in which the local variables were efficient in predicting environmental filters that influence the trophic organization. In this scenario, our study follows the longitudinal model and evidences a greater accumulation of energy in food webs in the upstream-downstream direction, which favors the greatest abundance of piscivorous, detritivorous and iliophagous verified in stretches of greater volume and dimensions of river. These results highlight the importance of the local variables and the interrelationships in the lateral connectivity processes along the river continuum.

link: https://www.jlimnol.it/index.php/jlimnol/article/view/jlimnol.2018.1738

Evolution of trans-Andean endemic fishes of the genus Cheirodon (Teleostei: Characidae) are associated with chromosomal rearrangements

Miguel Ángel Soto, Jonathan Pena Castro, Laura Ines Walker, Luiz Roberto Malabarba, Mateus Henrique Santos, Mara Cristina de Almeida, Orlando Moreira-Filho, and Roberto Ferreira Artoni

Abstract

Background

Among Neotropical fishes, the family Characidae is highly diverse and speciose and its taxonomy is not completely resolved. In Chile, the family is represented by five species, all within the genus Cheirodon, of which C. pisciculus, C. galusdae, C. kiliani, and C. australe are endemic, while C. interruptus is introduced. We compared chromosomal markers in order to appreciate the taxonomy and evolution of these trans-Andean fishes.

Results

The specimens were photographed in stereomicroscope to observe the ventral protrusive teeth and cusps for morphological analysis and species identification. All of the species analysed had equally diploid chromosome number 2n = 50, with karyotypes dominated by high number of acrocentric chromosomes as compared to those of other members of Cheirodontinae. The distribution of heterochromatin was inconspicuous and was similar in all the species. The number of active NORs (nucleolus organizer regions) was polymorphic, with the greater number of them in C. kiliani and C. galusdae. The location of 5S and 18S rDNA ranged in number and position, showing two sites in different chromosomes. The fluorescent in situ hybridization with telomeric probe did not reveal interstitial sites in all analysed species.

Conclusions

The comparative analysis of karyotypes and morphological markers revealed a biogeographic pattern of distribution, with the species that occur in the southern region forming one group and those in central and northern Chile forming another.

Link: https://link.springer.com/article/10.1186/s40693-018-0078-5

Fig. 4 Geographic regions of Chile (left), ideograms (middle) and photographs of teeth and caudal peduncle region (right) of Cheirodon species occurring in Chile. (a) Ch. interruptus from Estero Marga-Marga; V region, (b) Ch. pisciculus from Angostura River; Metropolitan region, (c) Ch. galusdae from Andalién River; VIII region, (d) Ch. kiliani from Calle-Calle River; XIV region and (e) Ch. australe from La Poza Lake; X region, base level Llanquihue Lake. Ideograms show 18S and 5S rDNA gene location. Mid-marks represent rDNA sites that may be present or absent, in the same individual (heteromorphism) or in different individuals (polymorphism). In the photographs of teeth bar: 500 μm, and in those of peduncle region bar: 2 mm

Fig. 5
Chromosomal phylogenetic hypothesis for five species of Cheirodon in Chile, with two species of genera Odontostilbe and Serrapinus serving as outgroups. The number of pericentric inversions (i) and Robertsonian fusions (f) implied in the clade divergence are included in the nodes