RESUMO

The current conservation status of Percichthys trucha (Creole perch) is Least Concern, although the population trend is considered to be decreasing. We conducted an extensive survey of parasite fauna in this species over two decades in its distribution range in Argentina. Fish were collected using gill and trawl nets. Parasites were collected, identified, and counted to calculate prevalence and mean intensity. The present work reports the parasite species infecting P. trucha, using data from our own survey and from previously published records. This information enables us to evaluate infection and distribution patterns, assess the role of P. trucha as host, determine the specificity of the parasites, and evaluate the threat represented by introduced, invasive parasites. The data set consists of a total of 453 host-parasite-locality records, of which only 15 are exclusively bibliographic. We found 44 parasite taxa: 19 digeneans, 4 monogeneans, 5 cestodes, 8 nematodes, 4 acanthocephalans, 3 crustaceans, and 1 mollusk. The most represented families were Diplostomidae, Heterophyidae, and Dactylogyridae. This study increases the number of parasite species known from 25 to 44. It can be concluded that this parasite fauna is characterized by high diversity, particularly of digeneans, and most of the parasites reproduce within this host, a pattern which is related to the top position of this fish species in the trophic webs. Six parasite species (Allocreadium patagonicum, Homalometron papilliferum, Acanthostomoides apophalliformis, Duplaccessorius andinus, Pseudodelphys limnicola, and Hysterothylacium patagonense) exhibit high host specificity (only matures in Creole perches) and are widely distributed, which could now be considered as "biogeographical core helminth fauna." Some P. trucha populations are affected by the invasion of alien fishes like Cyprinus carpio and pathogenic parasites like Lernaea cyprinacea and Schizocotyle acheilognathi. Our findings emphasize the need for further research.

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RESUMO

The Austrolebias adloffi species group encompasses a diverse lineage of annual killifishes that occurs along the Laguna dos Patos/Lagoa Mirim system, in both Brazilian and Uruguayan territories. We herein employ an integrative taxonomy approach to describe two new species of the group, inferring their phylogenetic relationships and evaluating their conservation status. Austrolebias cheffei sp. nov. and Austrolebias lourenciano sp. nov. are herein described from the western portion of the Laguna dos Patos system. Austrolebias cheffei is distinguished from the remaining species of the A. adloffi species group by presenting a yellowish green or yellowish blue dorsal fin, with wide black to dark brown bars extending from the base to the middle portion of the dorsal and anal fins in the males. Austrolebias lourenciano is distinguished from the remaining species of the A. adloffi species group by presenting a yellowish green dorsal fin, with light yellow or light bluish bars forming small triangles, interspersed with small dark brown rows of blotches in the dorsal fin base, and greenish blue anal fin, sometimes with lighter elongated yellowish iridescent blotches, limited to the basal region. According to mitochondrial cytb sequences, both species are reciprocally monophyletic relative to other species of the A. adloffi species group, and present positive barcoding gap values. Interestingly, both new species form a grade that is closely related to Austrolebias aff. minuano 1, an undescribed species that occurs at the opposite margin of the Laguna dos Patos. Among the other evaluated species, A. bagual, A. aff. minuano 1, A. nigrofasciatus, A. pelotapes, A. pongondo, A. arachan, and A. viarius also revealed to be reciprocally monophyletic, whereas A. minuano and A. adloffi revealed to be paraphyletic in regard to A. charrua and A. aff. minuano 2, respectively, and A. nachtigalli is subdivided in two clades, one of which including A. reicherti, which points to the need of a taxonomic review of the group. In addition, we discussed the conservation status of the new species, corrected the type locality of A. pongondo, and provided a dichotomous identification key of the A. adloffi species group.

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RESUMO

Myleus pachyodus, a new serrasalmid species, is described from the Rio Teles Pires and Rio Jamanxim, both tributaries of the Rio Tapajós in Mato Grosso and Pará states, Brazil. The new species differs from all congeners by having a remarkable ontogenetic thickening of the teeth shifting from slender incisiform in juveniles to thick bulky teeth at standard length ≥ 100 mm, whereas congeners present slender, antero-posteriorly flat teeth throughout all life stages. The new species further differs from congeners by having 18-20 branched dorsal-fin rays, by the lack of a diastema between contralateral outer series of premaxillary teeth and by the presence of 16-25 prepelvic spines, with the anteriormost spine never reaching the vertical through the pectoral-fin origin.

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RESUMO

The present study aimed to evaluate the activation characteristics of the lebranche mullet spermatozoa in natura and diluted with CF-HBSS for 96h at 4±2°C. The semen was collected from eight wild fish in Florianópolis – SC (Brazil) (27°S) in May, during reproductive migration. Three pools of semen were divided into two treatments: in natura and diluted with CF-HBSS 1:3. The semen was activated with seawater (salinity of 34, pH 8.7 and 4±2°C) to determine: motility time, motility rate and sperm cell membrane integrity. Dilution with CF-HBSS 1:3 increased motility time of diluted semen (15- 20% for 6, 12 and 18h). Motility rate was equal to fresh semen for up to 24h of refrigeration and it was 30% higher than in natura semen at 12, 18 and 24h. Cell membrane integrity was maintained in fresh semen up to 6h, and it was 15-20% higher than in natura semen from 6 to 48h (p < 0.05). The use of CF-HBSS as diluent in the ratio 1:3 is recommended for semen refrigeration of lebranche mullet.

O objetivo do presente estudo foi avaliar em tainha as características de ativação dos espermatozoides in natura e diluídos com CF-HBSS mantidos por 96h a 4±2°C. O sêmen foi coletado de oito peixes selvagens em Florianópolis – SC (27°S) em maio, durante a migração reprodutiva. Três pool de sêmen foram divididos em dois tratamentos: in natura e diluído com CF-HBSS 1:3. O sêmen foi ativado com água oceânica (34 de salinidade, pH 8,7 e 4±2°C) para determinar: tempo de motilidade, taxa de ativação espermática e integridade da membrana celular. A diluição com CF-HBSS 1:3 propiciou o aumento no tempo de motilidade do sêmen diluído (15-20% para 6, 12 e 18h); manteve a taxa de motilidade igual ao sêmen fresco por até 24h de refrigeração e foi 30% maior do que em in natura em 12, 18 e 24h; manteve também a integridade da membrana celular igual ao sêmen fresco por 6h e 15-20% maior que em sêmen in natura (p < 0.05) para o período de 6 a 48h. O uso do CF-HBSS como diluidor na proporção 1:3 é recomendado para a refrigeração do sêmen da tainha.

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RESUMO

Pirá, Conorhynchos conirostris (Valenciennes, 1840), a large migratory catfish endemic to the São Francisco River (SFR), is listed as threatened in the red lists of both Brazil and the state of Minas Gerais. Although fishing for pirá has been prohibited, it is still an important fishery resource, particularly in the middle SFR. We used historical and current occurrence and abundance data regarding pirá to determine if it meets the IUCN criteria of a threatened species. Pirá occurs in the main course of the SFR as well as in its major tributaries. Unlike the most well-known migratory fishes of the SFR, pirá does not use floodplain lakes as nurseries. In the first half of the 20th century, pirá occurred from the upper to the lower SFR. Currently, it is most abundant in the middle SFR, and is rare in the upper SFR and even rarer in the sub-middle SFR. Pirá has not been captured in the lower SFR since around the mid-1980's. Despite the reduction in its geographic distribution, we did not find evidence to justify considering pirá as threatened. Thus, we recommend that it be removed from the red lists of Brazil and the state of Minas Gerais.(AU)

Pirá, Conorhynchos conirostris (Valenciennes, 1840), um grande siluriforme migrador endêmico do rio São Francisco (RSF), está incluído como ameaçado nas listas vermelhas do Brasil e do estado de Minas Gerais. Embora sua pesca esteja proibida, ele ainda é recurso pesqueiro importante, particularmente no médio RSF. Utilizamos dados históricos e atuais de ocorrência e abundância do pirá para determinar se ele atende aos critérios da UICN para ser classificado como ameaçado. Pirá ocorre na calha do RSF, bem como em seus principais afluentes. Ao contrário dos peixes migradores mais conhecidos do RSF, ele não usa lagoas das várzeas como berçários. Na primeira metade do século 20, pirá costumava ocorrer do alto ao baixo RSF. Atualmente, ele é mais abundante no médio RSF. A espécie é rara no alto RSF e parece ainda mais rara no sub-médio RSF. O pirá não é capturado no baixo RSF desde cerca da metade da década de 1980. Apesar da redução na distribuição geográfica, não encontramos evidências para classificar o pirá como espécie ameaçada e, portanto, recomendamos que ele seja removido das listas vermelhas do Brasil e do estado de Minas Gerais.(AU)

Assuntos

RESUMO

The present study aimed to evaluate the activation characteristics of the lebranche mullet spermatozoa in natura and diluted with CF-HBSS for 96h at 4±2°C. The semen was collected from eight wild fish in Florianópolis SC (Brazil) (27°S) in May, during reproductive migration. Three pools of semen were divided into two treatments: in natura and diluted with CF-HBSS 1:3. The semen was activated with seawater (salinity of 34, pH 8.7 and 4±2°C) to determine: motility time, motility rate and sperm cell membrane integrity. Dilution with CF-HBSS 1:3 increased motility time of diluted semen (15- 20% for 6, 12 and 18h). Motility rate was equal to fresh semen for up to 24h of refrigeration and it was 30% higher than in natura semen at 12, 18 and 24h. Cell membrane integrity was maintained in fresh semen up to 6h, and it was 15-20% higher than in natura semen from 6 to 48h (p < 0.05). The use of CF-HBSS as diluent in the ratio 1:3 is recommended for semen refrigeration of lebranche mullet.(AU)

O objetivo do presente estudo foi avaliar em tainha as características de ativação dos espermatozoides in natura e diluídos com CF-HBSS mantidos por 96h a 4±2°C. O sêmen foi coletado de oito peixes selvagens em Florianópolis SC (27°S) em maio, durante a migração reprodutiva. Três pool de sêmen foram divididos em dois tratamentos: in natura e diluído com CF-HBSS 1:3. O sêmen foi ativado com água oceânica (34 de salinidade, pH 8,7 e 4±2°C) para determinar: tempo de motilidade, taxa de ativação espermática e integridade da membrana celular. A diluição com CF-HBSS 1:3 propiciou o aumento no tempo de motilidade do sêmen diluído (15-20% para 6, 12 e 18h); manteve a taxa de motilidade igual ao sêmen fresco por até 24h de refrigeração e foi 30% maior do que em in natura em 12, 18 e 24h; manteve também a integridade da membrana celular igual ao sêmen fresco por 6h e 15-20% maior que em sêmen in natura (p < 0.05) para o período de 6 a 48h. O uso do CF-HBSS como diluidor na proporção 1:3 é recomendado para a refrigeração do sêmen da tainha.(AU)

Assuntos

RESUMO

Pirá, Conorhynchos conirostris (Valenciennes, 1840), a large migratory catfish endemic to the São Francisco River (SFR), is listed as threatened in the red lists of both Brazil and the state of Minas Gerais. Although fishing for pirá has been prohibited, it is still an important fishery resource, particularly in the middle SFR. We used historical and current occurrence and abundance data regarding pirá to determine if it meets the IUCN criteria of a threatened species. Pirá occurs in the main course of the SFR as well as in its major tributaries. Unlike the most well-known migratory fishes of the SFR, pirá does not use floodplain lakes as nurseries. In the first half of the 20th century, pirá occurred from the upper to the lower SFR. Currently, it is most abundant in the middle SFR, and is rare in the upper SFR and even rarer in the sub-middle SFR. Pirá has not been captured in the lower SFR since around the mid-1980's. Despite the reduction in its geographic distribution, we did not find evidence to justify considering pirá as threatened. Thus, we recommend that it be removed from the red lists of Brazil and the state of Minas Gerais.(AU)

Pirá, Conorhynchos conirostris (Valenciennes, 1840), um grande siluriforme migrador endêmico do rio São Francisco (RSF), está incluído como ameaçado nas listas vermelhas do Brasil e do estado de Minas Gerais. Embora sua pesca esteja proibida, ele ainda é recurso pesqueiro importante, particularmente no médio RSF. Utilizamos dados históricos e atuais de ocorrência e abundância do pirá para determinar se ele atende aos critérios da UICN para ser classificado como ameaçado. Pirá ocorre na calha do RSF, bem como em seus principais afluentes. Ao contrário dos peixes migradores mais conhecidos do RSF, ele não usa lagoas das várzeas como berçários. Na primeira metade do século 20, pirá costumava ocorrer do alto ao baixo RSF. Atualmente, ele é mais abundante no médio RSF. A espécie é rara no alto RSF e parece ainda mais rara no sub-médio RSF. O pirá não é capturado no baixo RSF desde cerca da metade da década de 1980. Apesar da redução na distribuição geográfica, não encontramos evidências para classificar o pirá como espécie ameaçada e, portanto, recomendamos que ele seja removido das listas vermelhas do Brasil e do estado de Minas Gerais.(AU)

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RESUMO

A new species of Austrolebias is described from the middle course of the Rio Camaquã, Laguna dos Patos system, Rio Grande do Sul, Brazil. The new species belongs to the Austrolebias alexandri species group, which is distinguished from the remaining congeners by the presence of a dark gray pectoral fin with bright blue iridescence in males. The new species is distinguished from all remaining species of the A. alexandri species group by the following combination of characters: presence of well-defined bright blue bars on the flank in males, shorter caudal fin length in males and females, contact organs in the first three rays of the pectoral fin in males, one to two post-optic neuromasts (rarely three), basihyal width of 50% of the length, and basihyal cartilage about 50-60% of the basihyal length. The recognition of this new species belonging to the A. alexandri group endemic of the middle course of Rio Camaquã and the recent discovery of Austrolebias bagual in the same general region reinforces the claim of the middle Rio Camaquã basin as an area of endemism for annual fishes and as such, a priority area for conservation in southern Brazil.

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RESUMO

The aim of this study was to describe, for the first time, the embryogenesis and larval growth of the Paraitinga Brycon nattereri Günther, 1864 reared in captivity. After artificial fertilization, eggs were incubated at constant temperature (~19°C) and collected every 15 min during the first 3 h and then every 3 h until hatching. Five larvae were collected daily over 15 days for evaluation of the length, yolk sac volume and specific growth rate. The following stages of embryonic development were identified: zygote, cleavage, gastrula, segmentation and larval. The hatching occurred after 50-54 h, with larvae poorly developed and fully depigmented, devoid of mouth and swimming capacity, presenting 6.32 mm total length and 3.64 mm3 yolk sac volume. The mouth opening was observed between days 3-4 after hatching. The yolk sac absorption was slow during the first 3 days, increasing sharply after this period, being completed on the day 11. During this period there was a decrease in the larval growth rate. After yolk sac absorption, an increase in the growth rate was observed that coincided with the start of exogenous feeding. Cannibalism was not observed during the 15 days of evaluation. The initial development of B. nattereri was slow and poorly developed larvae in relation to other Brycon species, certainly due to the lower temperature required for egg incubation and larval rearing. Other studies are needed in order to develop techniques to improve the methods of incubating eggs and feeding larvae.

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