Redescription of Hypostomus johnii, a senior synonym of Hypostomus eptingi (Siluriformes: Loricariidae), Northeastern Brazil

Hypostomus johnii (Steindachner) was described from the rio Parnaíba basin in the state of Piauí and the rio São Francisco basin in the state of Bahia. Despite the good quality of the original description of H. johnii, it does not currently allow its distinction from congeners. Thus, H. johnii is redescribed based on the analysis of the types and several recently collected specimens. Recent collecting efforts of the rios Parnaíba and São Francisco basins resulted in specimens only being found in the rio Parnaíba basin. This raises doubts about whether H. johnii occurs in the rio São Francisco basin. The species is distinguished from its congeners by having a high number of teeth on the premaxilla and dentary (between 60-115); small to moderate-sized dark spots with a light background; absence of keels on flanks; and abdominal plates more evident on laterals. A lectotype of H. johnii is designated herein and H. eptingi is considered a junior synonym of H. johnii.(AU)

Hypostomus johnii (Steindachner) foi descrita a partir de espécimes da bacia do rio Parnaíba, no Estado do Piauí e da bacia do rio São Francisco, no Estado da Bahia. Apesar da descrição original de H. johnii ter sido adequada para a época, esta não permite atualmente a sua diferenciação dos outros congêneres. Portanto, H. johnii é redescrita, baseado na análise dos tipos e de espécimes recentemente coletados. Recentes esforços de coleta nas bacias do rios Parnaíba e São Francisco resultaram em espécimes coletados apenas na bacia do rio Parnaíba. Este fato coloca em dúvida a ocorrência de H. johnii na bacia do rio São Francisco. Hypostomus johnii é diferenciada de seus congêneres principalmente por possuir um elevado número de dentes no pré-maxilar e dentário (entre 60-115), por apresentar pequenas manchas escuras de tamanho moderado sobre um fundo claro; ausência de quilhas sobre flancos; e as placas do abdômen mais evidente nas laterais. Um lectótipo para H. johnii é aqui designado e H. eptingi é considerado sinônimo júnior de H. johnii.(AU)

Redescription of Hypostomus johnii, a senior synonym of Hypostomus eptingi (Siluriformes: Loricariidae), Northeastern Brazil

Hypostomus johnii (Steindachner) was described from the rio Parnaíba basin in the state of Piauí and the rio São Francisco basin in the state of Bahia. Despite the good quality of the original description of H. johnii, it does not currently allow its distinction from congeners. Thus, H. johnii is redescribed based on the analysis of the types and several recently collected specimens. Recent collecting efforts of the rios Parnaíba and São Francisco basins resulted in specimens only being found in the rio Parnaíba basin. This raises doubts about whether H. johnii occurs in the rio São Francisco basin. The species is distinguished from its congeners by having a high number of teeth on the premaxilla and dentary (between 60-115); small to moderate-sized dark spots with a light background; absence of keels on flanks; and abdominal plates more evident on laterals. A lectotype of H. johnii is designated herein and H. eptingi is considered a junior synonym of H. johnii.(AU)

Hypostomus johnii (Steindachner) foi descrita a partir de espécimes da bacia do rio Parnaíba, no Estado do Piauí e da bacia do rio São Francisco, no Estado da Bahia. Apesar da descrição original de H. johnii ter sido adequada para a época, esta não permite atualmente a sua diferenciação dos outros congêneres. Portanto, H. johnii é redescrita, baseado na análise dos tipos e de espécimes recentemente coletados. Recentes esforços de coleta nas bacias do rios Parnaíba e São Francisco resultaram em espécimes coletados apenas na bacia do rio Parnaíba. Este fato coloca em dúvida a ocorrência de H. johnii na bacia do rio São Francisco. Hypostomus johnii é diferenciada de seus congêneres principalmente por possuir um elevado número de dentes no pré-maxilar e dentário (entre 60-115), por apresentar pequenas manchas escuras de tamanho moderado sobre um fundo claro; ausência de quilhas sobre flancos; e as placas do abdômen mais evidente nas laterais. Um lectótipo para H. johnii é aqui designado e H. eptingi é considerado sinônimo júnior de H. johnii.(AU)

Use of food resources and resource partitioning among five syntopic species of Hypostomus (Teleostei: Loricariidae) in an Atlantic Forest river in southern Brazil

We analyzed the diet and resource partitioning among five syntopic species of Hypostomus Lacépède, 1803 in the Corumbataí River in southeastern Brazil. The gut contents of 352 individuals were assessed and 21 food items were identified and quantified under an optical microscope. The food items found in the gut contents indicate that these suckermouth loricariids are bottom-dwelling detritivorous/periphytivorous catfishes. PERMANOVA and SIMPER analyses indicated variation in the consumption of some resources, and the contribution of periphytic algae was primarily responsible for such dissimilarity. ECOSIM analyses of dietary overlap showed evidence of resource sharing among all species in the dry and rainy periods. This is most likely the result of the predominance of detritus and autochthonous items such as algae and aquatic immature insects in all gut contents. Our data suggest that trophic resources available in the Corumbataí River are explored and partitioned among Hypostomus species, all specialized in surface-grazing foraging behaviour.

Use of food resources and resource partitioning among five syntopic species of Hypostomus (Teleostei: Loricariidae) in an Atlantic Forest river in southern Brazil

We analyzed the diet and resource partitioning among five syntopic species of Hypostomus Lacépède, 1803 in the Corumbataí River in southeastern Brazil. The gut contents of 352 individuals were assessed and 21 food items were identified and quantified under an optical microscope. The food items found in the gut contents indicate that these suckermouth loricariids are bottom-dwelling detritivorous/periphytivorous catfishes. PERMANOVA and SIMPER analyses indicated variation in the consumption of some resources, and the contribution of periphytic algae was primarily responsible for such dissimilarity. ECOSIM analyses of dietary overlap showed evidence of resource sharing among all species in the dry and rainy periods. This is most likely the result of the predominance of detritus and autochthonous items such as algae and aquatic immature insects in all gut contents. Our data suggest that trophic resources available in the Corumbataí River are explored and partitioned among Hypostomus species, all specialized in surface-grazing foraging behaviour.(AU)