A Survey of the Brazilian Dicranocentrus Schött (Collembola, Orchesellidae, Heteromurini) with the Description of a New Species and Notes on the Genus

Dicranocentrus Schött is the most diverse and widespread taxon of Neotropical Orchesellidae. In Brazil, the genus is represented by 11 species found in humid forested areas of Atlantic and Amazon forests domains. Here we describe in detail Dicranocentrus abestado sp. nov. from Chapada Diamantina, Caatinga domain, Brazil. The new species belongs to the marias group sensu Mari-Mutt, due to the absence of most posterior macrochaetae on the dorsal head, and resembles other Neotropical species with 3, 2 and 2 central macrochaetae on abdominal segments I–III. However, the new species is unique especially by its reduced colour pattern combined with its empodial complex morphology. We compare Dicranocentrus abestado sp. nov. with 27 other taxa from the New and Old World, including all species with 3 macrochaetae on the first abdominal segment; provide notes and details on the morphology of the compared species plus identification keys to Brazilian and all species of the genus with similar abdominal chaetotaxy. We also discuss the current taxonomical knowledge on Brazilian Dicranocentrus and provide notes on its chaetotaxy and Heteromurinae systematics.

Atopsyche Banks (Trichoptera, Hydrobiosidae): New species, redescription, and new records

Atopsyche is the largest genus of hydrobiosids, comprising 139 species in three subgenera (Atopsyche, Atopsaura, and Dolochorema), distributed from southwestern United States to northeastern Uruguay. Atopsyche (Atopsaura) is the most diverse subgenus with 65 species, Atopsyche (Atopsyche) with 51, and Atopsyche (Dolochorema) with three. This paper provides a taxonomic study of Atopsyche, including descriptions of A. (Atopsyche) bravoi n. sp. from Ecuador, A. (Atopsaura) beckeri n. sp. from Cuba, A. (Atopsaura) japi n. sp. from Brazil, and the redescription of A. (Atopsaura) usingeri. Additionally, the morphological variations of A. (Atopsaura) antisuya and A. (Atopsaura) diamantina are presented, as well new records. These results contribute to taxonomical knowledge of Atopsyche and increase the number of described species to 142.

Poor taxonomical knowledge of larval fish prey preference is impeding our ability to assess the existence of a “critical period” driving year-class strength

Despite 100 years of research testing the link between prey availability during the larval stage and year-class strength, field-based evidence for Hjort's “critical period” hypothesis remains equivocal. Here, we argue that a minority of past studies have relied on sufficient taxonomical knowledge of larval fish prey preference to reveal the potential effects of variability in zooplankton prey production on larval vital rates and year-class strength. In contrast to the juvenile and adult stages, larval fish diet and prey field are often poorly resolved, resulting in the inclusion of zooplankton taxa that do not actually contribute to the diet as part of the prey field considered by fisheries scientists. Recent studies have demonstrated that when accounting for prey selectivity, the expected positive relationships between preferred prey availability and larval feeding success, growth and survival are revealed. We strongly recommend that laboratories conducting research on larval fish trophodynamics take prey selectivity into account and acquire the necessary taxonomic expertise for providing valid assessments of the influence of prey availability on larval vital rates. We make the prediction that the proportion of studies supporting the existence of a “critical period” will increase proportionally to the progress of knowledge on prey preference during the early larval stage.