Landscape dynamics and diversification of the megadiverse South American freshwater fish fauna

Landscape dynamics are widely thought to govern the tempo and mode of continental radiations, yet the effects of river network rearrangements on dispersal and lineage diversification remain poorly understood. We integrated an unprecedented occurrence dataset of 4,967 species with a newly compiled, time-calibrated phylogeny of South American freshwater fishes—the most species-rich continental vertebrate fauna on Earth—to track the evolutionary processes associated with hydrogeographic events over 100 Ma. Net lineage diversification was heterogeneous through time, across space, and among clades. Five abrupt shifts in net diversification rates occurred during the Paleogene and Miocene (between 30 and 7 Ma) in association with major landscape evolution events. Net diversification accelerated from the Miocene to the Recent (c. 20 to 0 Ma), with Western Amazonia having the highest rates of in situ diversification, which led to it being an important source of species dispersing to other regions. All regional biotic interchanges were associated with documented hydrogeographic events and the formation of biogeographic corridors, including the Early Miocene (c. 23 to 16 Ma) uplift of the Serra do Mar and Serra da Mantiqueira and the Late Miocene (c. 10 Ma) uplift of the Northern Andes and associated formation of the modern transcontinental Amazon River. The combination of high diversification rates and extensive biotic interchange associated with Western Amazonia yielded its extraordinary contemporary richness and phylogenetic endemism. Our results support the hypothesis that landscape dynamics, which shaped the history of drainage basin connections, strongly affected the assembly and diversification of basin-wide fish fauna

Characidium heirmostigmata, a new characidiin fish (Characiformes: Crenuchidae) from the upper rio Paraná basin, Brazil

Characidium heirmostigmata new species is described from the rio Ivaí drainage, upper rio Paraná basin, Paraná State, Brazil. The new species is diagnosed among its congeners by the possession of eight to 11 incomplete oblique dark bars on the body sides, extending upwards and downwards from the lateral line, independently of the eight or nine dorsal transverse bars usually present in species of Characidium. The new species is similar to Characidium serrano from the upper rio Uruguay basin, but differs by meristic and morphometric traits. Characidium heirmostigmata espécie nova é descrita da drenagem do rio Ivaí, bacia do alto rio Paraná, Estado do Paraná, Brasil. A nova espécie é diagnosticada de suas congêneres por apresentar oito a 11 barras escuras, oblíquas e incompletas nas laterais do corpo, para cima e para baixo da linha lateral, independentemente das oito ou nove barras transversais que geralmente estão presentes nas espécies de Characidium. A nova espécie é similar a Characidium serrano, da bacia do alto rio Uruguai, porém difere em caracteres merísticos e morfométricos

Description of males of Phallotorynus pankalos Lucinda, Rosa & Reis, 2005 and reappraisal of Phallotorynus species relationships (Teleostei: Cyprinodontiformes: Poeciliidae)

Recently discovered male specimens of Phallotorynus pankalos are described and diagnosed from males of congener species on the basis of gonopodial morphology, color pattern and number of dorsal and anal-fin rays. The phylogenetic hypothesis of relationships among Phallotorynus species is reappraised with the inclusion of P. pankalos. Phallotorynus pankalos is hypothesized as sister to P. jucundus, a clade sister to P. victoriae or to a clade composed of P. dispilos and P. psittakos. Biogeography of Phallotorynus species is discussed, and it is suggested: (1) an early basal split between the rio Paraíba do Sul drainage and the Paraná-Paraguay system, separating P. fasciolatus from the ancestor of the remaining Phallotorynus species followed by a dispersal to rio Paraíba do Sul; (2) that the formation of the Sete Quedas falls may have isolated the ancestors of P. psittakos and P. dispilos. However, the sequence of events associated with the evolutionary history of Phallotorynus remains unclear and unsatisfactory

Microglanis carlae, a new species of bumblebee catfish (Siluriformes: Pseudopimelodidae) from the río Paraguay basin in Paraguay

Microglanis carlae, new species, is described from the río Paraguay basin and distinguished from its congeners by the following combination of characters: paired and anal fins mottled or with thin faint bands, trunk with dark-brown saddles, anterior margin of pectoral spine with serrations retrorse proximally and antrorse distally, tip of pectoral spine as a distinct bony point, continuous portion of lateral line reaching vertical through last dorsal-fin ray, caudal peduncle with irregularly shaped, faint to dark blotch, maxillary barbel surpassing vertical through dorsal-spine origin, and dark bar on posterior flank continuous from base of adipose fin to that of anal fin. The new species is included in the Microglanis parahybae species complex on the basis of color pattern

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. camopiensisand 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