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BackgroundFreshwaters are the most threatened ecosystems on earth. Although recent assessments provide data on global priority regions for freshwater conservation, local scale priorities remain unknown. Refining the scale of global biodiversity assessments (both at terrestrial and freshwater realms) and translating these into conservation priorities on the ground remains a major challenge to biodiversity science, and depends directly on species occurrence data of high taxonomic and geographic resolution. Brazil harbors the richest freshwater ichthyofauna in the world, but knowledge on endemic areas and conservation in Brazilian rivers is still scarce.Methodology/Principal FindingsUsing data on environmental threats and revised species distribution data we detect and delineate 540 small watershed areas harboring 819 restricted-range fishes in Brazil. Many of these areas are already highly threatened, as 159 (29%) watersheds have lost more than 70% of their original vegetation cover, and only 141 (26%) show significant overlap with formally protected areas or indigenous lands. We detected 220 (40%) critical watersheds overlapping hydroelectric dams or showing both poor formal protection and widespread habitat loss; these sites harbor 344 endemic fish species that may face extinction if no conservation action is in place in the near future.Conclusions/SignificanceWe provide the first analysis of site-scale conservation priorities in the richest freshwater ecosystems of the globe. Our results corroborate the hypothesis that freshwater biodiversity has been neglected in former conservation assessments. The study provides a simple and straightforward method for detecting freshwater priority areas based on endemism and threat, and represents a starting point for integrating freshwater and terrestrial conservation in representative and biogeographically consistent site-scale conservation strategies, that may be scaled-up following naturally linked drainage systems. Proper management (e. g. forestry code enforcement, landscape planning) and conservation (e. g. formal protection) of the 540 watersheds detected herein will be decisive in avoiding species extinction in the richest aquatic ecosystems on the planet.

Monophyly of the Neotropical Characidiinae is established based on 13 synapomorphies: (1) dorsal lamina of mesethmoid bone very narrow; (2) mesethmoid bone separated from vomer by a large block of cartilage; (3) anterior and posterior nasal openings widely separated; (4) dorsal portion of infraorbital bone 1 greatly expanded vertically, forming anterior margin of orbit; (5) gap between the dentary and the angulo‐articular; (6) lamellar portion of infraorbital bones 3–6 greatly reduced, especially in the posterior bones, where it may be completely absent; (7) contact between the parasphenoid and the pterosphcnoid bones; (8) laterosensory canal piercing the sphenotic bone; (9) auditory foramen of prooptic bone circular and reduced in size; (10) absence of medial process on posttemporal bone; (11) three or more unbranched pectoral‐fin rays; (12) medial process on the ribs of the fifth vertebra; and (13) absence of circuli on the apical field of the scales. An analysis of characiform morphology reveals that all characters previously used in the literature to diagnose the group are plesiomorphic, equivocal, or misapplied at this level of generality. SUMMARY Although virtually no phylogenetic evidence (in the sense advocated by Hennig, 1966) had been previously presented to support the monophyly of the Characidiinae, and most 'diagnostic' characters used by previous authors were found to be unacceptable in a cladistic classification, i t is still possible to diagnose the Characidiinae in a phylogenetic sense. This study revealed the existence of 13 synapomorphies supporting the monophyly of the group. Several of these synapomorphies, such as the modifications associated with the mesethmoid, the jaw bones, and the ribs of the fifth vertebra, are unique to the Characidiinae, thus providing a solid basis for recognizing the group as a monophyletic unit of characiform fishes. Demonstration of characidiin monophyly provides a solid foundation for further phylogenetic analysis of characidiin interrelationships, and higher level relationships among characiform fishes.

Abstract— Miniaturization, which results in the presence of numerous apparently paedomorphic characters associated with reduced size, is a common phenomenon among neotropical fishes, with over 85 miniature species distributed among the five major ordinal groups. Eleven species are recognized as miniatures within the Characidiinae, a monophyletic subunit of Characiformes. A reconstruction of characidiin phylogeny is used to analyze the history of miniaturization events. Former hypotheses of origin of miniaturization among characidiins are rejected, underscoring the need for phylogenetic frameworks in the study of ontogenetic changes associated with the phenomenon of miniaturization. The 11 instances of miniature species can be most parsimoniously attributed to three independent miniaturization events within the Characidiinae. Reductive characters comprise a large proportion of phylogenetically informative characters within the Characidiinae. In the largest group of miniatures, reductive characters represent more than half of the character state transformations affecting supraspecific relationships among Elachocharax, Klausewitzia, Odontocharacidium and Microcharacidium. An analysis of patterns of character state distributions fails to reject the null hypothesis of character independence. A distinction is made between the concepts of character independence, defined as the origination of character states from different (non‐simultaneous) evolutionary events, and character correlation, defined as the association of character states in terminal taxa. Character correlation is not a sufficient criterion to reject Hennig's auxiliary principle, according to which the “presence of apomorphous characters in different species is always reason for suspecting kinship, and their origin by convergence should not be assumed a priori". High values of character correlation are the expected result of congruent patterns of character distribution.

Two new species of loricariid catfishes, Parotocinclus bidentatus and P. muriaensis, are described from the rio Paraíba do Sul basin. They possess accessory unicuspid teeth located internally to the series of bicuspid teeth in premaxillary and dentary bones. According to a parsimony analysis of phylogenetic relationships among the Hypoptopomatinae, the new taxa are members of the genus Parotocinclus, even though they lack a fully developed adipose fin. They differ from most species of Parotocinclus because they have accessory teeth. Within the Hypoptopomatinae, accessory teeth are also found only in P. collinsae and members of the genera Eurycheilichtys, Epactionotus and Niobichthys.
Duas novas espécies de cascudinhos loricariídeos, Parotocinclus bidentatus e P. muriaensis, são descritas da bacia do Rio Paraíba do Sul. Elas possuem dentes unicúspides localizados internamente à série de dentes bicúspides dos ossos pré-maxilar e dentário. De acordo com uma análise de parcimônia das relações filogenéticas entre os Hypoptopomatinae, as novas espécies pertencem ao gênero Parotocinclus, apesar de não possuírem a nadadeira adiposa plenamente desenvolvida. Elas diferem da maioria das espécies de Parotocinclus pela presença de dentes acessórios. Entre os Hypoptopomatinae dentes acessórios ocorrem apenas em P. collinsae e membros dos gêneros Eurycheilichthys, Epactionotus e Niobichthys

Cytogenetic studies were performed in two syntopic species of Characidium, C. lauroi and Characidium sp. cf. C. alipioi, from Ribeirão Grande, Paraíba do Sul river basin. Both species have diploid number 2n =50 chromosomes, but differ in chromosome shape, C-banding pattern and location of nucleolar organizing regions. In Characidium sp. cf. C. alipioi a new type of ZW sex chromosome system composed of equal sized metacentric chromosomes is reported for the first time in the genus Characidium. Species of Characidium with a sex chromosome system form a monophyletic group. Variations in this system are interpreted as resulting from geographic isolation among allopatric species.

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