Diet of two syntopic species of Crenuchidae (Ostariophysi: Characiformes) in an Amazonian rocky stream

Abstract This study assessed the diet of two poorly known syntopic fish species of the family Crenuchidae, Characidium aff. declivirostre and Leptocharacidium omospilus, in a Presidente Figueiredo´ rocky stream, Amazonas, Brazil. The stomach contents were analyzed and their Frequency of Occurrence (FO %) and Relative Volume (Vol %) were combined in a Feeding Index (IAi). We examined 20 individuals of C. aff. declivirostre and 23 of L. omospilus. The Morisita-Horn Index was used to estimate the overlap between the diets of these species. Immature insects were the most valuable items consumed by both fish species. The diet of C. aff. declivirostre was mainly composed of larvae and pupae of Chironomidae, while L. omospilus predominantly consumed larvae of Hydroptilidae, Hydropyschidae and Pyralidae. Thus, both species were classified as autochthonous insectivorous. Characidium aff. declivirostre was considered a more specialized species, probably reflecting lower feeding plasticity or the use of more restricted microhabitats compared to L. omospilus. When the food items were analyzed at the family taxonomic level, the diet overlap between these species was considered moderate (Morisita-Horn Index = 0.4). However, a more thorough analysis, at the genus level, indicates a very low diet overlap. Therefore, we conclude that the feeding segregation between C. aff. declivirostre and L. omospilus may favor their co-existence, despite their high phylogenetic closeness

Review of the genus Camelobaetidius Demoulin (Ephemeroptera: Baetidae) with reduced terminal filament

The genus Camelobaetidius has 38 valid species distributed throughout the Neotropical and Neartic Regions. The incomplete descriptions of some species of the genus, and the vast morphological variation among some specimens, makes the identification at specific level difficult in some cases. Currently there are eight species of the genus in which the nymphs possess the terminal filament reduced, all of them restricted to South America. The aim of this study was to review these species of Camelobaetidius. Camelobaetidius apis is considered a junior synonym of C. billi. The nymphs of six species are redescribed: C. billi, C. francischettii, C. ipaye, C. leentvaari, C. maranhensis and C. rufiventris. No specimen of Camelobaetidius mantis was studied, and the male imago of C. billi is redescribed. A key for the species of Camelobaetidius with reduced terminal filament is presented. © 2012 Copyright Taylor and Francis Group, LLC