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This study investigated the range-wide phylogenetics and biogeography of the Cape kurper Sandelia capensis, a primary freshwater fish endemic to and widespread within the Cape Floristic Region (CFR) of South Africa. Maximum likelihood, Bayesian phylogenetic and haplotype network analyses, based on two mitochondrial and two nuclear genes, revealed the existence of three reciprocally monophyletic, deeply divergent and allopatric clades that probably represent cryptic species. The West Coast Clade is largely confined to the Langvlei, Verlorenvlei, Berg and Diep Rivers, the Klein River Clade is endemic to the Klein River and the South Coast Clade is found everywhere else in the range of S. capensis sensu lato. It was hypothesised that divergences within S. capensis sensu lato probably occurred because of isolation of coastal drainages by persistent drainage divides or vicariance of current tributaries by the drowning of their confluences by high sea levels. The current distribution of lineages could be due to historical range expansion and gene flow via river capture or some other mode of transdivide dispersal or dispersal during periods of low sea level via palaeoriver confluences of currently isolated coastal rivers. Comparison of BEAST2 estimated divergence times with the timing of climatic, geological and geomorphological events supported long-term coastal drainage isolation, punctuated by rare transdivide dispersal events and limited palaeoriver dispersal, as the best explanation of current phylogeographic and divergence patterns in S. capensis. Hydrological barriers that block upstream passage in palaeotributaries could hypothetically explain why S. capensis failed to disperse through certain palaeoriver confluences. There were several sites where biogeographic patterns have likely been confounded by human translocation of S. capensis. Alien fish predators and water extraction may threaten the three cryptic species more severely than previously realised, due to their smaller population sizes and inhabitation of only a portion of the range previously ascribed to S. capensis sensu lato. The preponderance of cryptic diversity and endemism in the CFR suggests that additional undescribed cryptic species of obligate freshwater fishes may be found in short coastal river systems around the world, especially in regions with a history of geological stability and a narrow continental shelf., (© 2019 The Fisheries Society of the British Isles.)

In theory, evolutionary modularity allows anatomical structures to respond differently to selective regimes, thus promoting morphological diversification. These differences can then influence the rate and direction of phenotypic evolution among structures. Here we use geometric morphometrics and phenotypic matrix statistics to compare rates of craniofacial evolution and estimate evolvability in the face and braincase modules of a clade of teleost fishes (Gymnotiformes) and a clade of mammals (Carnivora), both of which exhibit substantial craniofacial diversity. We find that the face and braincase regions of both clades display different degrees of integration. We find that the face and braincase evolve at similar rates in Gymnotiformes and the reverse in Carnivora with the braincase evolving twice as fast as the face. Estimates of evolvability and constraints in these modules suggest differential responses to selection arising from fluctuations in phylogenetic integration, thus influencing differential rates of skull-shape evolution in these two clades.

The nearly 150 species of Anostomidae comprise one of the most diverse and taxonomically dynamic families of Neotropical freshwater fishes. A recent revision of the enigmatic and poorly diagnosed genus Anostomoides demonstrated that it contains two valid species, each with complicated taxonomic histories; however, that study did not address their phylogenetic placement. Herein, we integrate molecular and morphological data to demonstrate their distant evolutionary relationship, and thus the polyphyly of Anostomoides. While we reconstruct one of the species in a previously hypothesized placement within a clade also containing Laemolyta , Rhytiodus and Schizodon , the other represents a morphologically and genetically distinctive lineage that diverged early in the history of the family. We describe and illustrate the osteology of this remarkable species, discuss the evolutionary implications of its unique suite of features, and use those characteristics to diagnose a new genus that evolved independently of all other known members of the family for approximately 37 Myr. [ABSTRACT FROM AUTHOR]

Curimatidae, the fourth largest family of detritivorous Neotropical characiform fishes, encompasses eight extant genera and over 110 species dwelling in diverse freshwater habitats from Costa Rica to Argentina. Extensive phylogenetic analyses of soft anatomy and osteology provided evidence for intergeneric and most interspecific relationships, and formed the basis of curimatid taxonomy for nearly 40 years. However, that morphological phylogeny demonstrated incomplete phylogenetic resolution at various scales and has never been tested with extensive molecular data. Herein, we infer molecular phylogenies spanning ∼70% of the known species diversity using three nuclear and three mitochondrial loci. Topologies from concatenated likelihood and Bayesian analyses and coalescent Bayesian species trees agree broadly with each other, and with the prior morphological hypothesis in many, but not all respects. All molecular analyses support the monophyly of Curimatidae and of six of its constituent genera, and agree on the placement of Curimatopsis as sister to all other curimatids. DNA-based intergeneric relationships differ substantially from prior morphological hypotheses by placing Curimata sister to Potamorhina and Psectrogaster sister to Pseudocurimata , rather than in a ladderized arrangement. Our results also resolve a major uncertainty in the morphological tree by revealing Cyphocharax , a genus for which no anatomical synapomorphy has ever been proposed, as a paraphyletic assemblage containing a monophyletic Steindachnerina and a polyphyletic Curimatella . Overall, the phylogeny expands substantially our understanding of the morphology, phylogenetics and evolution of the Curimatidae, and will guide future intrageneric studies by improving precision in the choice of comparative taxa. [ABSTRACT FROM AUTHOR]

Pseudanos winterbottomi n. sp. from the Orinoco drainage of Venezuela and the Tapajós drainage of Brazil resembles Pseudanos gracilis (Kner) in meristic and morphometric characters but differs from it in possession of a single midlateral stripe instead of a series of lateral spots, four branchiostegal rays instead of three, two pores on the sensory canal of the nasal instead of one, four pores on the sensory canal of the first infraorbital arranged in a square instead of three pores arranged in a line or shallow V, a dorsal process on the mesopterygoid that wraps around the posterior of the palatine (vs absence of such a process), the absence of a thin, posteriorly directed process on the ectopterygoid running ventral to the palatine (vs presence of such a process), a thick, blocklike palatine instead of a thinner, platelike palatine, and an almost completely closed metapterygoid/quadrate fenestra (vs an open fenestra). An updated key to the anostomine characiforms of the genera Anostomus, Gnathodolus, Pseudanos, Sartor, and Synaptolaemus is presented. [ABSTRACT FROM AUTHOR]