Iguanodectinae

6 p. : ill. ; 26 cm.Includes bibliographical references (p. 6)."Piabucus caudomaculatus is a new species of iguanodectine characoid from Bolivia and the first member of the subfamily Iguanodectinae reported from that country. The Iguanodectinae are shown to share a series of modifications of the swimbladder, body wall, and anterior proximal pterygiophores, which distinguish them from other characoids and support the hypothesis of the monophyletic nature of the group"--P. [1]

Herbivory promotes dental disparification and macroevolutionary dynamics in grunters (teleostei: Terapontidae), a freshwater adaptive radiation

Trophic shifts into new adaptive zones have played major (although often conflicting) roles in reshaping the evolutionary trajectories of many lineages. We analyze data on diet, tooth, and oral morphology and relate these traits to phenotypic disparification and lineage diversification rates across the ecologically diverse Terapontidae, a family of Australasian fishes. In contrast to carnivores and most omnivores, which have retained relatively simple, ancestral caniniform tooth shapes, herbivorous terapontids appear to have evolved a variety of novel tooth shapes at significantly faster rates to meet the demands of plant-based diets. The evolution of herbivory prompted major disparification, significantly expanding the terapontid adaptive phenotypic continuum into an entirely novel functional morphospace. There was minimal support for our hypothesis of faster overall rates of integrated tooth shape, spacing, and jaw biomechanical evolution in herbivorous terapontids in their entirety, compared with other trophic strategies. There was, however, considerable support for accelerated disparification within a diverse freshwater clade containing a range of specialized freshwater herbivores. While the evolutionary transition to herbivorous diets has played a central role in terapontid phenotypic diversification by pushing herbivores toward novel fitness peaks, there was little support for herbivory driving significantly higher lineage diversification compared with background rates across the family

Terapon perches

8 p. : ill., map ; 26 cm."Two new species of freshwater teraponids, Syncomistes rastellus and Hephaestus epirrhinos, are described from the Kimberley region of northwestern Australia"--P. [1].Includes bibliographical references (p. 8)

Checklist of the freshwater fishes of Colombia

Data derived from the literature supplemented by examination of specimens in collections show that 1435 species of native fishes live in the freshwaters of Colombia. These species represent 14 orders and 47 families. Orders with the largest numbers of species in the Colombian continental ichthyofauna are the Characiformes (637 species), Siluriformes (524 species), Perciformes (124 species), and Gymnotiformes (74 species), with the remaining 10 orders having from 1 to 35 species. At the family level, the Characidae has the greatest number of species (399 species), with this followed by the Loricariidae (166 species), Cichlidae (114 species), Pimelodidae (54 species), and Trichomycteridae (54 species); the remaining 42 families having 1 to 52 species. Present data indicate that 311 of the species occur solely at locations within Colombia. Continued descriptions of new species from the continental waters of Colombia demonstrate that the present total underestimates the species-level diversity of the ichthyofauna. The 1435 species living in Colombian freshwaters represent approximately 5% of all freshwater and marine fish species now recognized worldwide and approximately 29% of the freshwater fish species known to inhabit the drainages across the expanse from the southern border of Mexico through to Chile and Argentina. Various historical and ecological factors potentially contributing to the species-level richness of the Colombian freshwater fish fauna are discussed (e.g. geology, climate, physiography, water chemistry)

Phylogenetic relationships within the speciose family Characidae (Teleostei: Ostariophysi: Characiformes) based on multilocus analysis and extensive ingroup sampling

<p>Abstract</p> <p>Background</p> <p>With nearly 1,100 species, the fish family Characidae represents more than half of the species of Characiformes, and is a key component of Neotropical freshwater ecosystems. The composition, phylogeny, and classification of Characidae is currently uncertain, despite significant efforts based on analysis of morphological and molecular data. No consensus about the monophyly of this group or its position within the order Characiformes has been reached, challenged by the fact that many key studies to date have non-overlapping taxonomic representation and focus only on subsets of this diversity.</p> <p>Results</p> <p>In the present study we propose a new definition of the family Characidae and a hypothesis of relationships for the Characiformes based on phylogenetic analysis of DNA sequences of two mitochondrial and three nuclear genes (4,680 base pairs). The sequences were obtained from 211 samples representing 166 genera distributed among all 18 recognized families in the order Characiformes, all 14 recognized subfamilies in the Characidae, plus 56 of the genera so far considered <it>incertae sedis </it>in the Characidae. The phylogeny obtained is robust, with most lineages significantly supported by posterior probabilities in Bayesian analysis, and high bootstrap values from maximum likelihood and parsimony analyses.</p> <p>Conclusion</p> <p>A monophyletic assemblage strongly supported in all our phylogenetic analysis is herein defined as the Characidae and includes the characiform species lacking a supraorbital bone and with a derived position of the emergence of the hyoid artery from the anterior ceratohyal. To recognize this and several other monophyletic groups within characiforms we propose changes in the limits of several families to facilitate future studies in the Characiformes and particularly the Characidae. This work presents a new phylogenetic framework for a speciose and morphologically diverse group of freshwater fishes of significant ecological and evolutionary importance across the Neotropics and portions of Africa.</p

Global diversity patterns of freshwater fishes - Potential victims of their own success

Aim To examine the pattern and cumulative curve of descriptions of freshwater fishes world-wide, the geographical biases in the available information on that fauna, the relationship between species richness and geographical rarity of such fishes, as well as to assess the relative contributions of different environmental factors on these variables. Location Global. Methods MODESTR was used to summarize the geographical distribution of freshwater fish species using information available from data-based geographical records. The first-order jackknife richness estimator was used to estimate the completeness of such data in all terrestrial 1-degree cells world-wide. An a-shape procedure was used to build range maps capable of providing relatively accurate species richness and geographical rarity values for each grid cell. We also examined the explanatory capacity of a high number of environmental variables using multiple regressions and Support Vector Machine. Results Cumulative species description curves show that a high number of species of freshwater fishes remain to be discovered. Completeness values indicate that only 199 one-degree grid cells, mainly located in eastern North America and Europe, could be considered as having relatively accurate inventories. Range maps provide species richness values that are positively and significantly related to those resulting from the first-order jackknife richness estimator. The relationship between species richness and geographical rarity is triangular, so that these species-rich cells are those with a higher proportion of distributionally rare species. Species richness is predicted by climatic and/or productivity variables but geographical rarity is not. Main conclusions In general, species-rich tropical areas harbour a higher number of narrowly distributed species although comparatively species-poor subtropical cells may also contain narrowly distributed species. Historical factors may help to explain the faunistic composition of these latter areas; a supposition also supported by the low predictive capacity of climatic and productivity variables on geographical rarity values

Unexpected species diversity in electric eels with a description of the strongest living bioelectricity generator

Is there only one electric eel species? For two and a half centuries since its description by Linnaeus, Electrophorus electricus has captivated humankind by its capacity to generate strong electric discharges. Despite the importance of Electrophorus in multiple fields of science, the possibility of additional species-level diversity in the genus, which could also reveal a hidden variety of substances and bioelectrogenic functions, has hitherto not been explored. Here, based on overwhelming patterns of genetic, morphological, and ecological data, we reject the hypothesis of a single species broadly distributed throughout Greater Amazonia. Our analyses readily identify three major lineages that diverged during the Miocene and Pliocene—two of which warrant recognition as new species. For one of the new species, we recorded a discharge of 860 V, well above 650 V previously cited for Electrophorus, making it the strongest living bioelectricity generator. © 2019, The Author(s)