a b s t r a c tSome species of copepods are sensitive to water quality oscillations from natural or anthropogenic causes. Information on basic ecological attributes such as abundance can be helpful in the context of hydric resources monitoring. Our study analyzed if the abundance of 22 copepod species of the second largest basin of South America was more associated with variables oscillating by natural or anthropic causes, contrasting among oligotrophic, mesotrophic, and eutrophic reservoirs. Our aim was to identify and understand the abundance of species with potential to monitor water quality in large scale assessments. Potential bioindicators would have different abundances in eutrophic, mesotrophic and oligotrophic sites and would not oscillate according to natural characteristics of reservoirs (water temperature, air temperature, and depth). Two species were sensitive to eutrophication and were not related to natural characteristics of reservoirs, that is, they were suitable for biomonitoring the La Plata Basin. Thermocyclops minutus negatively responded to eutrophication, while Acanthocyclops robustus responded positively. Additional exploratory analyses identified that Copepod abundance was related to total phosphorus, chlorophyll-a concentration, water transparency, total suspended matter, and depth. Metacyclops mendocinus, Acanthocyclops robustus, Mesocyclops meridianus, Mesocyclops ogunnus, and Thermocyclops decipiens were abundant in eutrophic reservoirs, and Thermocyclops minutus, and Thermocyclops inversus were associated with higher water transparency, typically oligo/mesotrophic reservoirs. Overall, we found that cyclopoids are highly affected by eutrophication, and species abundance could be used to monitor reservoirs and anticipate potential impacts on water quality in large-scale biomonitoring schemes.

IntroductionDiaptomid copepods are prevalent throughout continental waters of the Neotropics, yet little is known about their biogeography. In this study we investigate the main biogeographical patterns among the neotropical freshwater diaptomid copepods using Parsimony Analysis of Endemicity (PAE) based on species records within ecoregions. In addition, we assess potential environmental correlates and limits for species richness.ResultsPAE was efficient in identifying general areas of endemism. Moreover, only ecoregion area showed a significant correlation with diaptomid species richness, although climatic factors were shown to provide possible upper limits to the species richness in a given ecoregion.ConclusionThe main patterns of endemism in neotropical freshwater diaptomid copepods are highly congruent with other freshwater taxa, suggesting a strong historical signal in determining the distribution of the family in the Neotropics.

An identification guide is presented for species of calanoid copepod family Diaptomidae from “de la Plata” River Basin (Argentina, Brazil, Bolivia, Paraguay and Uruguay). It was based on material collected during the summer and winter of 2010 from 43 sites across the eastern part and the lower stretches of this basin, the second largest in South America and the fourth in the world. The guide contains identification keys and species diagnoses for males and females, richly supported by scanning electronic micrographs and/or line drawings of 19 species. It also includes some general remarks on the taxonomy and phylogenetic relationships of these species. The key was adjusted to be useful for these species only, with separate keys for each sex, and is the first for females of South America. One species classified herein as incertae sedis was not included in the analysis. At least ten other species have previously been recorded in the basin but were not present in our samples. This is the first attempt to compile comprehensive taxonomic information on this group of copepods in this region, and it is expected to become a useful tool for biologists and young taxonomists interested in the crustacean biota of the Neotropical region.

TIn this study we present 208 new diaptomids records, including 36 species from 10 genera. They are the result of new samplings as well as of the revision of samples from previous surveys from various localities in the Neotropical Region. In an attempt to clear elucidate about the species ranges we gathered all biogeographically important data and present them here, with comments about the relevance of each record to the understanding of the distribution of the group.

The first record of Argyrodiaptomus bergi (Richard, 1897) from a small roadside pool at high altitude in the southern region of Brazil is presented. This is the ninth record of this species in South America (previously known from Argentina and Uruguay) since its original description, and a new occurrence after 36 years, extending its known distribution to the northeast. The environments where this species was found differ sharply, and possible explanations include the loss of habitat, high species selectivity or deficient sampling efforts. An additional description is provided, with scanning electron microscopy (SEM) photomicrographs and line drawings. Similarly to other species of Argyrodiaptomus, such as Argyrodiaptomus falcifer (Daday, 1905), Argyrodiaptomus denticulatus (Pesta, 1927) and Argyrodiaptomus granulosus (Brehm, 1933), this species shows a restricted distribution in the lower stretches of the Paraná and Uruguay rivers, particularly in small pools. The importance of better understanding the dynamics and diversity of small water bodies is discussed

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In this work we present an analysis of upgraded characters used in the taxonomy of cyclopine copepods to provide a new key for the identification of the members of the freshwater genus Mesocyclops recorded in the neotropical region. This analysis, which included revision of type and museum specimens, resulted also in the clarification of the taxonomical status of two nominal species not previously revised, M. varius Dussart, 1987 and M. venezolanus Dussart, 1987. These two species are recognized herein as junior synonyms of M. brasilianus Kiefer, 1933. Considering the addition of new records (introduced Afro-Asian or Asian forms), the designation of M. araucanus Campos et al., 1974 to species rank, and the conflict of determining the taxonomical status of M. annulatus diversus, the number of taxa recognized in the region includes 20 species and one variety. A general morphological analysis of the Old and New World species allowed us to contrast and evaluate some of the differential characters of these two groups. We propose several characters that can be considered as potentially valuable to separate reliably both female and male specimens of the neotropical species. The distribution of selected species or species groups of Mesocyclops is also revised in light of this new frame.

ABSTRACT.A new genus of Parastenocarididae is described from the Neotropical region. Iticocaris gen. nov. is established to include Parastenocaris itica Noodt, 1962. Iticocaris gen. nov. is defined by the following characters: 1) male leg 3 with 2-segmented exopod; 2) first exopodal segment short and rectangular; 3) thumb hypertrophic, longer than the second exopodal segment and inserted on the distal edge of exopod segment 1, occupying the whole distal margin; 4) exopod 2 or apophysis strongly sclerotized, articulated with the exopod segment 1 on its inner margin and curved against the thumb, forming a strong forceps; 5) leg 4 endopod without dimorphism in shape and size vs. minor dimorphism in ornamentation; 6) leg 5 with three setae and 7) lack of the anterolateral furcal seta II. The new genus is monotypic, represented by Iticocaris itica (Noodt, 1962) comb. nov., from El Salvador, Central America. A close relationship is hypothesized between I. itica and the genus Brasilibathynellocaris Jakobi, 1972, the males of which both share the forceps-like elongated apophysis. KEYWORDS.Freshwater, Neotropics, Parastenocarididae, Taxonomy.RESUMO. Proposta de um novo gênero para Parastenocaris itica (Copepoda, Harpacticoida) de El Salvador, América Central e discussão dos grupos Parastenocaris fontinalis e P. proserpina. Um novo gênero de Parastenocarididae é proposto para a Região Neotropical para incluir Parastenocaris itica Noodt, 1962. Iticocaris gen. nov. é diagnosticado pela presença dos seguintes caracteres: 1) toracópodo 3 do macho com exópodo bissegmentado; 2) primeiro segmento exopodal curto e retangular; 3) "thumb" hipertrófico, mais longo que o segundo segmento do exópodo e inserido na margem distal do exópodo 1, ocupando toda a margem distal do segmento; 4) exópodo 2 ou apófise fortemente esclerotizado, articulado com o exópodo 1 em sua margem interna e curvado contra o "thumb", formando um forte fórceps; 5) endópodo do toracópodo 4 sem dimorfismo sexual quanto à forma e tamanho vs. discreto dimorfismo quanto à ornamentação; 6) toracópodo 5 com três cerdas e 7) furca sem a cerda anterolateral II. O novo gênero é monotípico, sendo representado por Iticocaris itica (Noodt, 1962) comb. nov., proveniente de El Salvador na América Central. É hipotetizado que I. itica e o gênero Brasilibathynellocaris Jakobi, 1972 sejam próximos filogeneticamente, possuindo os machos de ambos os gêneros uma apófise alongada e "thumb" formando uma estrutura similar a um fórceps.