Genetic assimilation and the evolution of direction of genital asymmetry in anablepid fishes.

Phylogenetic comparative studies suggest that the direction of deviation from bilateral symmetry (sidedness) might evolve through genetic assimilation; however, the changes in sidedness inheritance remain largely unknown. We investigated the evolution of genital asymmetry in fish of the family Anablepidae, in which males' intromittent organ (the gonopodium, a modified anal fin) bends asymmetrically to the left or the right. In most species, males show a 1 : 1 ratio of left-to-right-sided gonopodia. However, we found that in three species left-sided males are significantly more abundant than right-sided ones. We mapped sidedness onto a new molecular phylogeny, finding that this left-sided bias likely evolved independently three times. Our breeding experiment in a species with an excess of left-sided males showed that sires produced more left-sided offspring independently of their own sidedness. We propose that sidedness might be inherited as a threshold trait, with different thresholds across species. This resolves the apparent paradox that, while there is evidence for the evolution of sidedness, commonly there is a lack of support for its heritability and no response to artificial selection. Focusing on the heritability of the left : right ratio of offspring, rather than on individual sidedness, is key for understanding how the direction of asymmetry becomes genetically assimilated.

Molecular characterization of Moenkhausia (Pisces: Characiformes) populations with different lateral line developmental levels.

The genera Hemigrammus and Moenkhausia have been traditionally diagnosed mainly by the former having lateral line completely pored whereas the latter having a lateral line with a few pored scales. Those features have been used to diagnose species of both genera in the upper Paraná River floodplain. Specimens with the diagnostic features of Moenkhausia bonita, collected in the upper Paraná River floodplain, exhibited different developmental levels of the lateral line, making it difficult to distinguish them from specimens of Hemigrammus sp. We analyzed the gene encoding cytochrome C oxidase I (COI) and intron 1 of the nuclear gene S7 to investigate the genetic similarities between the called Hemigrammus marginatus and M. bonita and to confirm their identities. Molecular sequences of other Moenkhausia species were analyzed for genus delimitation tests. The results reveal genetic similarities of M. bonita specimens with different developmental levels of the lateral line, and also distinguish between M. bonita and Hemigrammus sp. Species delimitation tests revealed that specimens from the upper Paraná River floodplain were M. bonita and were distinct from other Moenkhausia species. The developmental level of the lateral line is not a consistent characteristic that distinguishes between Moenkhausia and Hemigrammus species.

Satanoperca curupira, a new cichlid species from the rio Madeira basin in Brazil (Teleostei: Cichlidae).

Satanoperca curupira, new species, is described from the rio Madeira basin in the State of Rondônia, Brazil. It is distinguished from all congeners by the following combination of characters: 3-7 dark-brown oblique stripes on the lachrymal (vs. 2 well-defined dark-brown stripes, or dark-brown stripes absent) and an irregular pattern of dark-brown stripes on cheek and opercular series (vs. cheek without dark-brown markings or with light-beige rounded spots). According to meristic and color pattern characters, the new species is considered a member of the S. jurupari species group, and is syntopic with S. jurupari, which is widespread in the Amazon basin. The restricted geographical range of the new species is congruent to that observed for some other Satanoperca species.

A new colorful species of Geophagus (Teleostei: Cichlidae), endemic to the rio Aripuanã in the Amazon basin of Brazil

Geophagus mirabilis, new species, is endemic to the rio Aripuanã drainage upstream from Dardanelos/Andorinhas falls. The new species is distinguished from all other species of the genus by the presence of one to five large black spots arranged longitudinally along the middle of the flank, in addition to the black midlateral spot that is characteristic of species in the genus and by a pattern of iridescent spots and lines on the head in living specimens. It is further distinguished from all congeneric species, except G. camopiensis and G. crocatus, by the presence of seven (vs. eight or more) scale rows in the circumpeduncular series below the lateral line (7 in G. crocatus; 7-9 in G. camopiensis). Including the new species, five cichlids and 11 fish species in total are known only from the upper rio Aripuanã, and 15 fish species in total are known only from the rio Aripuanã drainage.

Geophagus mirabilis, espécie nova, é endêmica da drenagem do rio Aripuanã, a montante das quedas de Dardanelos/Andorinhas. A espécie nova se distingue de todas as outras espécies do gênero pela presença de uma a cinco manchas pretas grandes distribuídas longitudinalmente ao longo do meio do flanco, em adição à mancha preta no meio do flanco característica das espécies do gênero, e por um padrão de pontos e linhas iridescentes sobre a cabeça em espécimes vivos. Além disso, se distingue de todas as espécies congêneres, exceto G. camopiensis e G. crocatus, pela presença de sete (vs. oito ou mais) séries de escamas na série circumpeduncular abaixo da linha lateral (7 em G. crocatus; 7-9 em G. camopiensis). Com a espécie nova existem cinco ciclídeos, e ao todo 11 espécies de peixe conhecidas somente do alto rio Aripuanã, e ao todo 15 espécies de peixe conhecidas apenas da bacia do rio Aripuanã.

A new colorful species of Geophagus (Teleostei: Cichlidae), endemic to the rio Aripuanã in the Amazon basin of Brazil

Geophagus mirabilis, new species, is endemic to the rio Aripuanã drainage upstream from Dardanelos/Andorinhas falls. The new species is distinguished from all other species of the genus by the presence of one to five large black spots arranged longitudinally along the middle of the flank, in addition to the black midlateral spot that is characteristic of species in the genus and by a pattern of iridescent spots and lines on the head in living specimens. It is further distinguished from all congeneric species, except G. camopiensis and G. crocatus, by the presence of seven (vs. eight or more) scale rows in the circumpeduncular series below the lateral line (7 in G. crocatus; 7-9 in G. camopiensis). Including the new species, five cichlids and 11 fish species in total are known only from the upper rio Aripuanã, and 15 fish species in total are known only from the rio Aripuanã drainage.(AU)

Geophagus mirabilis, espécie nova, é endêmica da drenagem do rio Aripuanã, a montante das quedas de Dardanelos/Andorinhas. A espécie nova se distingue de todas as outras espécies do gênero pela presença de uma a cinco manchas pretas grandes distribuídas longitudinalmente ao longo do meio do flanco, em adição à mancha preta no meio do flanco característica das espécies do gênero, e por um padrão de pontos e linhas iridescentes sobre a cabeça em espécimes vivos. Além disso, se distingue de todas as espécies congêneres, exceto G. camopiensis e G. crocatus, pela presença de sete (vs. oito ou mais) séries de escamas na série circumpeduncular abaixo da linha lateral (7 em G. crocatus; 7-9 em G. camopiensis). Com a espécie nova existem cinco ciclídeos, e ao todo 11 espécies de peixe conhecidas somente do alto rio Aripuanã, e ao todo 15 espécies de peixe conhecidas apenas da bacia do rio Aripuanã.(AU)