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The high diversity of extant gobiids (Gobiidae: Teleostei) makes taxonomic and phylogenetic interpretation of fossil members of the clade a difficult task. To facilitate future taxonomic and systematic work on the group, we have assembled a morphological reference database encompassing skeletal characters, an otolith atlas and otolith morphometric data of 25 present-day species from the European Gobius lineage (s.l.) that represent 18 different genera and include all nine sublineages. We show that: (1) skeletal traits and morphometric otolith variables can be diagnostic for a sublineage; (2) otolith morphology allows identification at the genus and species levels; and (3) the number of anal-fin rays and details of the otolith margins can be used to discriminate closely related dwarf gobies. The skeletal and otolith characters are largely stable in the marine gobies analysed here, whereas freshwater gobies (Padogobius , Ponto-Caspian gobies) are far more variable. This might be related to the conquest by Padogobius and Ponto-Caspian gobies of freshwater and low-salinity habitats, in which environmental conditions can fluctuate widely. We anticipate that the database presented here can be used as a valuable reference tool to assess the relationships of fossil gobiids and increase our knowledge of the evolutionary history of the group as a whole. [ABSTRACT FROM AUTHOR]

Two new Kneria species, K. luansaensis sp. nov. and K. maxi sp. nov., are described from the Luansa River, a left bank tributary of the lower Luapula in the Bangweulu–Mweru ecoregion, based on an integrative approach using morphological and COI barcoding evidence. While K. luansaensis sp. nov. occurs from the source of the Luansa further downstream to above the last of the three Sanshifolo Falls, K. maxi sp. nov. only occurs downstream of all these three major falls. In Kneria, males of about ≥ 33 mm LS have an opercular and a postopercular organ. The number of lamellae on the latter seems to contain some alpha-taxonomic information, although this requires further study as allometric changes occur at about ≤ 45 mm LS. Additional external morphological characters differ between sexes, i.e., the (i) pectoral fin width (wider in males than females), (ii) dorsal fin height (longer in males than females), and (iii) length of the longest ray of the lower caudal fin lobe (longer in males than females). Agriculture, fishing with ichthyotoxines, and logging are the most pressing threats on the Luansa and thus to both the new species. Their discovery in one of the rivers of the Kundelungu Plateau and its surroundings located outside the present-day boundaries of the Kundelungu National Park highlights the need for a refined and improved protection strategy for this freshwater key biodiversity area. [ABSTRACT FROM AUTHOR]

In the welcome circumstance that species believed extinct are rediscovered, it is often the case that biological knowledge acquired before the presumed extinction is limited. Efforts to address these knowledge gaps, in particular to assess the taxonomic integrity and conservation status of such species, can be hampered by a lack of genetic data and scarcity of samples in museum collections. Here, we present a proof‐of‐concept case study based on a multidisciplinary data evaluation approach to tackle such problems. The approach was developed after the rediscovery, 40 years after its presumed extinction, of the enigmatic Lake Constance deep‐water charr Salvelinus profundus. Targeted surveys led to the capture of further species and additional sympatric normal charr, Salvelinus cf. umbla. Since the lake had been subject to massive stocking in the past, an evaluation of the genetic integrity of both extant forms was called for in order to assess possible introgression. A two‐step genomic approach was developed based on restriction site associated DNA (RAD). Diagnostic population genomic (single nucleotide polymorphism [SNP]) data were harvested from contemporary samples and used for RNA bait design to perform target capture in DNA libraries of archival scale material, enabling a comparison between extant and historic samples. Furthermore, life history traits and morphological data for both extant forms were gathered and compared with historical data from the past 60–120 years. While extant deep‐water charr matched historical deep‐water specimens in body shape, gill raker count, and growth rates, significant differences were discovered between historical and extant normal charr. These resulted were supported by genomic analyses of contemporary samples, revealing the two extant forms to be highly divergent. The results of population assignment tests suggest that the endemic deep‐water charr persisted in Lake Constance during the eutrophic phase, but not one of the historical genomic samples could be assigned to the extant normal charr taxon. Stocking with non‐endemic charr seems to be the most likely reason for these changes. This proof‐of‐concept study presents a multidisciplinary data evaluation approach that simultaneously tests population genomic integrity and addresses some of the conservation issues arising from rediscovery of a species characterized by limited data availability. [ABSTRACT FROM AUTHOR]

A new species, Parakneria alytogrammus, is described from the main stream of the Upper Lufira River. This species is easily distinguished from its congeners from the Congo Basin by its unique colouration, consisting of a low number of transversal bands on each of the caudal‐fin lobes, 2 (vs. 3–5) and the presence of an uninterrupted lateral mid‐longitudinal black band in fresh and preserved specimens (vs. absent). In addition, the new species differs from its Upper Lualaba congeners by the narrow width of its pectoral‐fin base, 4.8–5.6% LS [vs. wider, 8.2–10.1% for P. lufirae, 8.6% LS for P. damasi (holotype), and 7.6–7.9% LS for P. thysi]. Finally, it differs from the only species currently known from the Luapula‐Mweru system, P. malaissei, by having a short post‐dorsal distance, 36.4–36.6% LS (vs. longer, 38.6–41.1% LS) and a short post‐pelvic distance of 40.0–40.6% LS (vs. longer, 41.4–44.1% LS). Mitochondrial DNA‐haplotypes of P. alytogrammus sp. nov. form a clade, which is sister to the P. thysi clade, and from which it diverges by a genetic (Kimura 2‐parameter and uncorrected p) distance of 0.7% in the COI‐barcoding locus. The Upper Lufira, one of the sub‐basins of the Upper Congo Basin, remains poorly explored relative to its fish fauna. In contrast, the region is well explored with regard to its mineral wealth. Unfortunately, mining exploitation is carried out in the region without proper concern for the environment. Thus, the discovery of this new species for science calls for increased protection and aquatic biodiversity exploration in this mining region. [ABSTRACT FROM AUTHOR]

The small cyprinid genus Prolabeops Schultz, 1941 is restricted to the Nyong and Sanaga River systems in Cameroon. In the past, the genus had been suggested to be either a member of the Labeoninae, Torinae or the Smiliogastrinae mainly on the basis of morphological similarities, and it is nowadays considered as incertae sedis within the Cypriniformes. This study provides the first attempt to reveal the phylogenetic position of Prolabeops using molecular data. For this purpose, the authors sequenced a large fraction of the mitochondrial genome (c. 13,600 bp), including all mitochondrial protein coding genes, of two Prolabeops melanhypopterus specimens and an additional four Enteromius specimens. The large‐scale phylogenetic analysis was based on an alignment including all mitochondrial protein coding genes of 902 specimens representing c. 899 cypriniform species. Prolabeops was clearly recovered within the African Smiliogastrinae, forming a weakly supported clade together with Enteromius jae, Enteromius hulstaerti and Barboides gracilis. The study data underline the urgent need of a thorough taxonomic revision of the small African barbs collectively placed in the genus Enteromius. [ABSTRACT FROM AUTHOR]

Freshwater habitats of the Caucasus biodiversity hotspot represent a center of endemism for the gobiid genus Ponticola Iljin, 1927. Hitherto, large‐scale molecular studies, owing to restricted taxon and geographical sampling, have failed to give an elaborate picture of diversity and evolutionary history of these species. Here, to contribute to filling this gap, we assessed taxonomic diversity, phylogeography and evolutionary history for the south Caspian populations of Ponticola presently classified as P. iranicus and P. patimari, using an integrative taxonomic approach comprising an entire geographic range sampling, and analyses of mitochondrial DNA haplotypes, the head lateral line system, otolith shape, and meristic and morphometric variation. All freshwater samples of the P. syrman group belong to a monophyletic clade with two main subclades: a small subclade confined to the upper Sefidroud sub‐basin including the type locality of P. iranicus and a large subclade with three geographically constrained haplogroups (Hg1, Hg2, and Hg3), comprising the rest of the distribution. Hg1 showed an eastern distribution including the type locality of P. patimari, while Hg2 and Hg3 are sister groups with central and western‐central distributions, respectively. The freshwater clade diverged from P. syrman during the Tyurkyanian low stand (~150 m b.s.l. lasting ~0.1 Myr), while the divergence of P. iranicus and P. patimari and radiations within P. patimari took place during the Bakunian high stand (up to 50 m a.s.l. lasting ~378–480 kya). Species delimitation analyses indicated two distinct species, corresponding to each main subclade. Although the otolith shape and lateral line analyses did not reflect with phylogeographic pattern, PCA and DFA plots of meristic and morphometric data showed a clear separation of the two major subclades corresponding to P. iranicus and P. patimari, suggesting the presence of significant morphological variation meriting formal taxonomic recognition. Overall, our findings (i) reveal the presence of two freshwater endemic species in the P. syrman group, and pending further investigation, hypothesize the presence of a third cryptic species; (ii) revise and document a narrow distributional range and low diversity for P. iranicus, in contrast to a wider distributional range and high diversity for P. patimari; (iii) suggest that the climatic oscillations of the Pleistocene were associated with the cladogenesis within the P. syrman group; and (iv) allowed for the recognition of conservation units and proposition of management measures. [ABSTRACT FROM AUTHOR]

Several hundred catfish species (order: Siluriformes) belonging to 11 families inhabit Africa, of which at least six families are endemic to the continent. Although four of those families are well‐known to belong to the 'Big‐Africa clade', no previous study has addressed the phylogenetic placement of the endemic African catfish family Austroglanididae in a comprehensive framework with molecular data. Furthermore, interrelationships within the 'Big‐Africa clade', including the most diverse family Mochokidae, remain unclear. This study was therefore designed to help reconstruct inter‐ and intrarelationships of all currently valid mochokid genera, to infer their position within the 'Big Africa clade' and to establish a first molecular phylogenetic hypothesis of the relationships of the enigmatic Austroglanididae within the Siluriformes. We assembled a comprehensive mitogenomic dataset comprising all protein coding genes and representing almost all recognized catfish families (N = 33 of 39) with carefully selected species (N = 239). We recovered the monophyly of the previously identified multifamily clades 'Big Asia' and 'Big Africa' and determined Austroglanididae to be closely related to Pangasiidae, Ictaluroidea and Ariidae. Mochokidae was recovered as the sister group to a clade encompassing Auchenoglanididae, Claroteidae, Malapteruridae and the African Schilbeidae, albeit with low statistical support. The two mochokid subfamilies Mochokinae and Chiloglanidinae as well as the chiloglanid tribe Atopochilini were recovered as reciprocally monophyletic. The genus Acanthocleithron forms the sister group of all remaining Mochokinae, although with low support. The genus Atopodontus is the sister group of all remaining Atopochilini. In contrast to morphological reconstructions, the monophyly of the genus Chiloglanis was strongly supported in our analysis, with Chiloglanis macropterus nested within a Chiloglanis sublineage encompassing only other taxa from the Congo drainage. This is an important result because the phylogenetic relationships of C. macropterus have been controversial in the past, and because we and other researchers assumed that this species would be resolved as sister to most or all other members of Chiloglanis. The apparent paraphyly of Synodontis with respect to Microsynodontis provided an additional surprise, with Synodontis punu turning out to be the sister group of the latter genus. [ABSTRACT FROM AUTHOR]

The magnitude of biodiversity in the Caucasus biodiversity hotspot remains largely unknown, because species diversity is usually assessed based on morphology. One ecologically important fish group with cryptic diversity is the tubenose goby members of the genus Proterorhinus, for which recent studies have shown that species assignments are difficult.Using mitochondrial COI data (652 bp) from 59 widespread localities, a phylogenetic and phylogeographical framework is applied to assess the species‐level status of different Caucasian populations of Proterorhinus, previously classified as Proterorhinusnasalis. We infer how post‐Miocene evolution of the Caspian basin may have shaped the present diversity and distribution of P. nasalis.The results suggest that Proterorhinus diversity in the Caucasus has been underestimated: (i) specimens from Azerbaijan and the Samur River delta on the Caspian shore share haplotypes with Proterorhinus semipellucidus; (ii) specimens from the Black Sea shore at Kodori Bay, the Kintrishi, and Mcnishta rivers of Georgia share haplotypes with two lineages of Proterorhinussemilunaris; and (iii) south Caspian specimens from the Iranian sites studied belong to P. nasalis.A pattern of low haplotype and nucleotide diversity was observed in P. nasalis, suggesting a founder event by a single or a few mitochondrial haplotypes following the isolation between the Black and Caspian seas in the early Pliocene or a demographic bottleneck during salinity and lake‐level changes in the Babadjanian, Balakhanian and Tyurkyanian stages.Integrative use of genetic assessments for monitoring Caucasian biodiversity will help to understand the extent of biodiversity and reliably assess threat status for critical species. Considering the species' narrow distribution range, small population size and low genetic variability, P. nasalis may merit an upgrade from Least Concern to an IUCN Red List Threatened Category (i.e. Vulnerable, Endangered or Critically Endangered). [ABSTRACT FROM AUTHOR]

A mitochondrial DNA analysis of the cichlid species found at two lakes in Cameroon reveals the monophyletic nature of the flocks. This suggests that each lake was colonized once with subsequent separation being sympatric in nature. The Bermin species possesses glycine at position 32 in the cytochrome b sequence that possibly originated in the stock that colonized the lake.

Abstract Background For decades cichlid fishes (Perciformes: Cichlidae) of the East African cichlid radiations (Teleostei: Cichlidae) have served as natural experimental subjects for the study of speciation processes and the search for potential speciation key factors. Despite numerous phylogenetic studies dealing with their intragroup relationships, surprisingly little is known about the phylogenetic placement and time of origin of this enigmatic group. We used multilocus DNA-sequence data from five nuclear and four mitochondrial genes and refined divergence time estimates to fill this knowledge gap. Results In concordance with previous studies, the root of the East African cichlid radiations is nested within the so called "Tilapias", which is a paraphyletic assemblage. For the first time, we clarified tilapiine intragroup relationships and established three new monophyletic groups:"Oreochromini", "Boreotilapiini" and a group with a distribution center in East/Central Africa, the "Austrotilapiini". The latter is the founder lineage of the East African radiations and emerged at the Miocene/Oligocene boundary at about 14 to 26 mya. Conclusion Our results provide the first resolved hypothesis for the phylogenetic placement of the megadiverse East African cichlid radiations as well as for the world's second most important aquaculture species, the Nile Tilapia, Oreochromis niloticus. Our analyses constitute not only a robust basis for African cichlid phylogenetics and systematics, but provide a valid and necessary framework for upcoming comparative phylogenomic studies in evolutionary biology and aquaculture.

Abstract Background Traditionally the rapid origin of megadiverse species flocks of extremely closely related species is explained by the combinatory action of three factors: Disruptive natural selection, disruptive sexual selection and partial isolation by distance. However, recent empirical data and theoretical advances suggest that the diversity of complex species assemblages is based at least partially on the hybridization of numerous ancestral allopatric lineages that formed hybrids upon invasion of new environments. That reticulate speciation within species flocks may occur under sympatric conditions after the primary formation of species has been proposed but not been tested critically. Results We reconstructed the phylogeny of a complex cichlid species flock confined to the tiny Cameroonian crater lake Barombi Mbo using both mitochondrial and nuclear (AFLP) data. The nuclear phylogeny confirms previous findings which suggested the monophyly and sympatric origin of the flock. However, discordant intra-flock phylogenies reconstructed from mitochondrial and nuclear data suggest strongly that secondary hybridization among lineages that primarily diverged under sympatric conditions had occurred. Using canonical phylogenetic ordination and tree-based tests we infer that hybridization of two ancient lineages resulted in the formation of a new and ecologically highly distinct species, Pungu maclareni. Conclusions Our findings show that sympatric hybrid speciation is able to contribute significantly to the evolution of complex species assemblages even without the prior formation of hybrids derived from allopatrically differentiated lineages.

Paragobiocichla, new genus, is established for Gobiochromis irvinei Trewavas, 1943, a rheophilic cichlid fish from the Volta River drainage in Ghana and Burkina Faso. It had previously been placed in the genus Stentocranus Boulenger, 1899 (synonyma Leptotilapia Pellegrin, 1928 and Gobiochromis Poll, 1939), which otherwise contains only members endemic to the Congo River basin. However, it is distinguished from Steatocranus by having cycloid scales on the opercle (vs. none in Steatocranus) and by 11-13 gill rakers on the first arch (vs. 4-10 in Steatocranus). [ABSTRACT FROM AUTHOR]

A morphological case study, including 25 meristics and 31 measurements of 37 Labeobarbus specimens from the Inkisi basin, Lower Congo, is presented. Two groups of specimens express either Labeobarbus -like (rubberlip) or Varicorhinus -like (chiselmouth) mouth phenotypes and a third group is morphologically intermediate. Rubberlip and chiselmouth specimens differ significantly from each other in some meristics and morphometrics, and all three phenotypes of this Inkisi complex form a strongly supported monophylum based on mitochondrial (COI) and nuclear (AFLP) DNA phylogenetic inferences. Tree-based analyses designed to differentiate between polymorphism, incipient speciation and hybridization scenarios, in combination with multivariate PCA of AFLP multilocus genotypes, revealed substantial, non-random genomic variation, which correlated strongly with the three major mouth phenotype groups and favours a scenario of secondary hybridization between primarily distinct parental lineages. Consequently, the two distinct mouth phenotypes are described taxonomically as species taxa and the various morphological intermediates are characterized as hybrid phenotypes. This study suggests that a new interpretation of the alpha-level taxonomy of the hexaploid Torini is necessary. These proposed changes are highlighted and discussed for African Torini. A typology of Labeobarbus mouth phenotypes was developed, which will be useful for future studies. [ABSTRACT FROM AUTHOR]

Invasive alien species are a major threat to aquatic biodiversity. Europe's second largest river, the Danube, is affected by several invasions, including those by four closely related Ponto-Caspian goby species. To investigate population dynamics of invasive alien gobies, we surveyed population trends of all goby species, from absence until full establishment of the round goby (Neogobius melanostomus), along a 248 Km river section of the upper Danube River. Distribution and abundance of non-native gobies was highly species-specific and varied with both time (year) and space (location). Gobies strongly dominated the fish community along the entire sampled study area, comprising 76% of all caught individuals, whereas abundances of typical native species such as chub (5%), barbel (4%) and ide (3%) were low. Ten years after its first introduction, round goby is most successful in terms of abundance, tubenose goby is most successful in terms of range expansion and persistence, whereas bighead goby seemingly lost the race. While being decoupled from industrial shipping, goby invasion success strongly appears to be triggered by man-made ecosystem alterations and community changes. [ABSTRACT FROM AUTHOR]

Phylogenetic studies focusing on Salmonidae have revealed significant obstacles in trying to clarify some interspecific relationships within the Salmoninae subfamily, due to a limited number of markers typed, conflicting phylogenetic signals and ancient hybridization events. To infer reliable phylogenetic relationships, evaluate several putative scenarios of ancient hybridization, and estimate divergence times within Salmoninae, we applied restriction-site associated DNA sequencing (RAD-seq) to 43 samples, including 26 genetic lineages across 21 species, largely representing the subfamily, with an emphasis on the genus Salvelinus . We identified 28,402 loci and 28,363 putatively unlinked SNPs, which were used in downstream analyses. Using an iterative k-means partitioned dataset and a Maximum Likelihood approach; we generated a well-supported phylogeny, providing clear answers to several previous phylogenetic uncertainties. We detected several significant introgression signals, presumably ancient, in the genus Salvelinus . The most recent common ancestor of Salmonidae dates back to approximately 58.9 MY ago (50.8–64 MY) and the crown age of Salmoninae was estimated to be 37.7 MY (35.2–40.8 MY) using a Bayesian molecular dating analysis with a relaxed molecular clock. The divergence among genera of the subfamily occurred between the late Eocene and middle of the Miocene (≈38–11 MY) such as the divergence between the genus Oncorhynchus and Salvelinus , which we estimated to 21.2 MY ago (95% HPD: 19.8–23.0 MY), while species diversification took place mainly during the Neogene (≈22–1.5 MY), with more than half of these events occurring in the last 10 MY. [ABSTRACT FROM AUTHOR]

Few studies have systematically investigated mid- or long-term temporal changes of biological characteristics in invasive alien species considering the different phases of an invasion. We studied the invasion performance of one of the most invasive species worldwide, the round goby Neogobius melanostomus, from total absence over first occurrence until establishment from 2010 to 2015 in the upper Danube River. After an upstream movement of the invasion front of about 30 river km within four years, the pattern that round goby pioneering populations significantly differ from longer established ones has been confirmed: Pioneering populations at the invasion front comprised more females than males, and adult specimens with a larger body size compared to those at longer inhabited areas. On the population-level, the proportion of juveniles increased with time since invasion. The results of this study provide support for the previously postulated ´bigger is better´ and ´individual trait utility´ hypotheses explaining invasion success in round goby. Pioneering invaders with their greater exploratory behavior, highly adaptive phenotypic plasticity and increased competitive ability seem to act as prime emperors of new habitats, strongly following and benefiting from man-made river-bank structures. [ABSTRACT FROM AUTHOR]

The relative importance of species-specific biological trait characteristics and environmental factors in invasions of nonindigenous species remains controversial because both have mostly been studied independently. Thus, the main objective of this study was to examine the correlation of biological traits with environmental variation in the globally invasive round goby Neogobius melanostomus from the upper Danube River. Based on a sample of 653 specimens along a continuous 200 km river pathway, links between nine environmental factors (substrate-type, six water measurements, and the communities of fishes and macroinvertebrates) and seven biological traits (nutritional and energetic status, trade-offs of parasite resistance and resource allocation, and three growth proxies) were analyzed. Biological trait values of N. melanostomus hardly correlated with the environment, could not explain invasion progress and imply a general low overall importance for invasion success. Instead, alternative individual life-history trajectories appear to determine invasion success. This is in line with up to 15% of all specimens having outlying biological trait values of potential adaptive value, suggesting a considerable importance of adaptive trait variation among single individuals for the whole invasion progress. This 'individual trait utility hypothesis' gives an alternative explanation for success of invasive species by single individuals carrying particular traits, and it should be specifically targeted and analyzed at currently invaded sites. [ABSTRACT FROM AUTHOR]

A review of the tumultuous history of the alpha- and genus-level taxonomy of the hexaploid African Torini, i.e. L abeobarbus s.l. (synonym: V aricorhinus), as well as of the closely related monospecific genera A capoeta and S anagia, is provided. The main purpose of the present paper is to provide a continental framework for multidisciplinary research on this megadiverse vertebrate group. Based on the inspection of almost all relevant type specimens, a complete and fully annotated checklist of all valid species and junior synonyms is provided for each of the four nominal genera. It comprises ∼275 nominal taxa, 125 of which are valid African L abeobarbus spp. and three of which are formally named hybrid phenotypes. Particular attention is drawn to the diversity and taxon-specific distribution of mouth phenotypes, which previously served as generic identification characters, i.e. 'rubberlips' with strongly developed, sometimes hypertrophied lips and a mental lobe, and 'chiselmouths' (former V aricorhinus spp.) with a cornified sharp cutting edge on their lower jaw. Interestingly, many species are polymorphic and include a large array of intermediate mouth phenotypes. The recurrent occurrence of similar mouth phenotype diversity within, but also far beyond, the borders of L abeobarbus s.l. is highlighted, raising numerous evolutionary questions. © 2016 The Linnean Society of London [ABSTRACT FROM AUTHOR]

A long history of research focused on the East Africa cichlid radiations (EAR) revealed discrepancies between mtDNA and nuclear phylogenies, suggesting that interspecific hybridisation may have been significant during the radiation of these fishes. The approximately 250 cichlid species of Lake Tanganyika have their roots in a monophyletic African cichlid assemblage, but controversies remain about the precise phylogenetic origin and placement of different lineages and consequently about L. Tanganyika colonization scenarios. 3312 AFLP loci and the mitochondrial ND2 gene were genotyped for 91 species representing almost all major lacustrine and riverine haplotilapiine east African cichlid lineages with a focus on L. Tanganyika endemics. Explicitly testing for the possibility of ancient hybridisation events, a comprehensive phylogenetic network hypothesis is proposed for the origin and diversification of L. Tanganyika cichlids. Inference of discordant phylogenetic signal strongly suggests that the genomes of two endemic L. Tanganyika tribes, Eretmodini and Tropheini, are composed of an ancient mixture of riverine and lacustrine lineages. For the first time a strong monophyly signal of all non-haplochromine mouthbrooding species endemic to L. Tanganyika (“ancient mouthbrooders”) was detected. Further, in the genomes of early diverging L. Tanganyika endemics Trematocarini, Bathybatini, Hemibatini and Boulengerochromis genetic components of other lineages belonging to the East African Radiation appear to be present. In combination with recent palaeo-geological results showing that tectonic activity in the L. Tanganyika region resulted in highly dynamic and heterogeneous landscape evolution over the Neogene and Pleistocene, the novel phylogenetic data render a single lacustrine basin as the geographical cradle of the endemic L. Tanganyika cichlid lineages unlikely. Instead a scenario of a pre-rift origin of several independent L. Tanganyika precursor lineages which diversified in ancient rivers and precursor lakes and then amalgamated in the extant L. Tanganyika basin is put forward as an alternative: the 'melting pot Tanganyika' hypothesis. [ABSTRACT FROM AUTHOR]

The article discusses the discovery of a new haplochromine cichlid species from the Great Ruaha River drainage in the Rufiji basin of Tanzania in 2014. Topics covered include the materials and methods used in the study which involved the morphological comparisons of 169 specimens of rheophilic haplochromine cichlid specimens, the taxonomy of the species, and its differential diagnosis.

Background The Malili Lakes system in central Sulawesi (Indonesia) is a hotspot of freshwater biodiversity in the Wallacea, characterized by endemic species flocks like the sailfin silversides (Teleostei: Atherinomorpha: Telmatherinidae) radiation. Phylogenetic reconstructions of these freshwater fishes have previously revealed two Lake Matano Telmatherina lineages (sharpfins and roundfins) forming an ancient monophyletic group, which is however masked by introgressive hybridization of sharpfins with riverine populations. The present study uses mitochondrial data, newly included taxa, and different external calibration points, to estimate the age of speciation and hybridization processes, and to test for phylogeographic relationships between Kalyptatherina from ancient islands off New Guinea, Marosatherina from SW Sulawesi, and the Malili Lakes flock. Results Contrary to previous expectations, Kalyptatherina is the closest relative to the Malili Lakes Telmatherinidae, and Marosatherina is the sister to this clade. Palaeogeographic reconstructions of Sulawesi suggest that the closer relationship of the Malili Lakes radiation to Kalyptatherina might be explained by a 'terrane-rafting' scenario, while proto-Marosatherina might have colonized Sulawesi by marine dispersal. The most plausible analysis conducted here implies an age of c. 1.9 My for the onset of divergence between the two major clades endemic to Lake Matano. Diversification within both lineages is apparently considerably more recent (c. 1.0 My); stream haplotypes present in the sharpfins are of even more recent origin (c. 0.4 My). Conclusions Sulawesi's Telmatherinidae have most likely originated in the Sahul Shelf area, have possibly reached the island by both, marine dispersal and island/terrane-rafting, and have colonized the Malili Lakes system from rivers. Estimates for the split between the epibenthic sharpfins and the predominantly pelagic to benthopelagic roundfins in Lake Matano widely coincide with geological age estimates of this rift lake. Diversification within both clades clearly predates hybridization events with stream populations. For Lake Matano, these results support a scenario of initial benthic-pelagic divergence after colonization of the lake by riverine populations, followed by rapid radiation within both clades within the last 1 My. Secondary hybridization of stream populations with the sharpfins occurred more recently, and has thus most likely not contributed to the initial divergence of this benthic species flock. [ABSTRACT FROM AUTHOR]

Approximately ten to 15 generations after first inoculation, two invasive goby species Neogobius melanostomus and Ponticola kessleri have dispersed and established rapidly the upper Danube River. Population genomic amplified length polymorphism (AFLP) data show that the genome of the more recent newcomer, i.e. the globally invasive N. melanostomus, is significantly differentiated to a comparatively large degree (~ 5%) and exhibits pronounced small-scale population structure along a recently invaded 200 km river section. MtDNA haplotype identity over N. melanostomus samples suggests that an admixture of phylogenetically strongly differentiated source populations is unlikely. Fine-scaled local genetic population structure of N. melanostomus as deduced from Bayesian assignment tests suggest a trisection of the upper Danube instead of a clinal pattern: one downstream sample is assigned together with distant upstream samples to one population cluster. A second cluster comprises central samples, whereas two samples from the margins of this central region appear to have mixed ancestry. AFLP genome scan results indicate this population structure is strongly correlated with extrinsic (geographic) parameters, i.e. migration barriers of anthropogenic origin. However, divergence of at least one AFLP locus correlates positively with a proxy for trophic differentiation, i.e. variation of white muscle d15N stable isotope signature. In contrast to N. melanostomus, no significant population differentiation was detectable in P. kessleri along the analyzed invasion pathway. In genome scans of P. kessleri, variation of a single locus is strongly positively correlated with an extrinsic parameter combination but not with any ecological parameter. [ABSTRACT FROM AUTHOR]

Few studies have systematically investigated differences in performance, morphology and parasitic load of invaders at different stages of an invasion. This study analyzed phenotype-environment correlations in a fish invasion from initial absence until establishment in the headwater reach of the second largest European river, the Danube. Here, the round goby (Neogobius melanostomus) formed 73% of the fish abundance and 58% of the fish biomass in rip-rap bank habitats after establishment. The time from invasion until establishment was only about two years, indicating rapid expansion. Founder populations from the invasion front were different from longer established round goby populations in demography, morphology, feeding behaviour, sex ratio and parasitic load, indicating that plasticity in these traits determines invasion success. Competitive ability was mostly dependent on growth/size-related traits rather than on fecundity. As revealed by stable isotope analyses, specimens at the invasion front had a higher trophic position in the food web and seem to benefit from lower food competition. Somatic performance seems to be more important than investment in reproduction during the early stages of the invasion process and upstream-directed range expansion is not caused by out-migrating weak or juvenile individuals that were forced to leave high density areas due to high competition. This mechanism might be true for downstream introductions via drift. Greater abundance and densities of acanthocephalan endoparasites were observed at the invasion front, which contradicts the expectation that invasion success is determined by lower parasitic pressure in newly invaded areas. Overall, the pronounced changes in fish and invertebrate communities with a dominance of alien species suggest invasional meltdown and a shift of the upper Danube River towards a novel ecosystem with species that have greater resistance to goby predation. This seems to contribute to overcoming biological resistance and improve rapidity of dispersal. [ABSTRACT FROM AUTHOR]

Highlights: [•] Phylogenetic analyses of a comprehensive multilocus dataset comprising almost all haplotilapiine cichlid tribes. [•] Enlarged mtDNA (ND2) dataset comprising about 60% of all described Pseudocrenilabrinae genera. [•] A novel classification of “Tilapia” and related lineages defined by putative molecular synapomorphies. [ABSTRACT FROM AUTHOR]

Hybridization between invasive and native species accounts among the major and pernicious threats to biodiversity. The Mozambique tilapia Oreochromis mossambicus, a widely used freshwater aquaculture species, is especially imperiled by this phenomenon since it is recognized by the IUCN as an endangered taxon due to genetic admixture with O. niloticus an invasive congeneric species. The Lower Limpopo and the intermittent Changane River (Mozambique) drain large wetlands of potentially great importance for conservation of O. mossambicus, but their populations have remained unstudied until today. Therefore we aimed (1) to estimate the autochthonous diversity and population structure among genetically pure O. mossambicus populations to provide a baseline for the conservation genetics of this endangered species, (2) to quantify and describe genetic variation of the invasive populations and investigate the most likely factors influencing their spread, (3) to identify O. mossambicus populations unaffected by hybridization. Bayesian assignment tests based on 423 AFLP loci and the distribution of 36 species-specific mitochondrial haplotypes both indicate a low frequency of invasive and hybrid genotypes throughout the system, but nevertheless reveal evidence for limited expansion of two alien species (O. niloticus and O. andersonii) and their hybrids in the Lower Limpopo. O. mossambicus populations with no traces of hybridization are identified. They exhibit a significant genetic structure. This contrasts with previously published estimates and provides rather promising auspices for the conservation of O. mossambicus. Especially, parts of the Upper Changane drainage and surrounding wetlands are identified as refugial zones for O. mossambicus populations. They should therefore receive high conservation priority and could represent valuable candidates for the development of aquaculture strains based on local genetic resources. [ABSTRACT FROM AUTHOR]

Invasive fish species can have major impacts on freshwater faunas, particularly in isolated systems harbouring adaptive animal radiations. Here, we report on the occurrence and recent rapid expansion of the hybridogenic "flowerhorn" cichlid in ancient Lake Matano, the hydrological head of the Malili Lakes system in Central Sulawesi, Indonesia. We show that flowerhorns rapidly dispersed along the lake's shoreline, inhabited most of the southern inshore habitats in 2010, and were present all around the lake in mid-2012. In addition, we present stomach content and observational data supporting the hypothesis that this cichlid threatens the local fauna through both predation and competition. We discuss 13 additional alien fish species recorded in the Malili Lakes drainage since 2000, including the recent, first record of the invasive sailfin catfish Pterygoplichthys pardalis for Sulawesi, highlighting the multitude of artificial introductions of foreign fish species into these unique and highly isolated freshwater systems. We conclude that alien fish species pose both serious and diverse threats to the fauna of the Malili Lakes system -- an ecosystem of high socio-economic importance and an exceptional natural laboratory for study of evolution, referred to as "Wallace's Dreamponds". Finally, we provide recommendations for minimizing future alien species introductions. [ABSTRACT FROM AUTHOR]

The article focuses on the first record of the Ponto-Caspian racer goby Babka gymnotrachelus from a Danube backwater near the city of Regensburg, Germany and from the main channel near the village of Mariaposching. The previously reported four invasive benthophiline freshwater gobies from the Lower Rhine and Upper Danube in Germany and Austria are given. The taxonomy of Babka gymnotrachelus is discussed.

The article describes the species of Liopropoma emanueli from the Cape Verde Islands. It is similar to a Liopropoma from São Tomé Island and from Brazil. It differs from all described Liopropoma species because of the dorsal fin that is clearly divided, more than 50 lateral line scales and numerous thin yellow lines on a pink body. The taxonomy of Liopropoma emanueli is discussed including the types, diagnosis and etymology.

The Mozambique tilapia Oreochromis mossambicus (Teleostei, Cichlidae) has been transplanted worldwide during the 20th century, and now belongs to the list of the most invasive species. Using a geometric morphometric approach, we describe body shape differentiation among 15 populations from native (Mozambique) and invaded (New Caledonia and Guadeloupe) ranges. A dominant phylogeographic signal is detected, despite the broad range of environmental conditions at the local scale. This result suggests that phylogeographic background rather than phenotypic plasticity responding to environmental variation constitutes the main factor correlated with shape divergence. This could result from successive founder events that occurred during the process of colonization of new geographic areas, and therefore strongly suggests heritable phenotypic differentiation. In addition, shape changes along a major axis of divergence hypothetically refer to different swimming abilities, possibly related to divergent functional requirements between the native and invaded ranges. Overall, patterns of contemporary shape diversification in O. mossambicus probably result from both phylogenetic constraints and adaptive divergence processes. We show that critically taking into account recent phylogenetic history of populations as a constraint on rapid phenotypic divergence is necessary for an improved view of contemporary evolution. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 105, 369-381. [ABSTRACT FROM AUTHOR]

Most freshwater diversity is arguably located in networks of rivers and streams, but, in contrast to lacustrine systems riverine radiations, are largely understudied. The extensive rapids of the lower Congo River is one of the few river stretches inhabited by a locally endemic cichlid species flock as well as several species pairs, for which we provide evidence that they have radiated in situ. We use more that 2,000 AFLP markers as well as multilocus sequence datasets to reconstruct their origin, phylogenetic history, as well as the timing of colonization and speciation of two Lower Congo cichlid genera, Steatocranus and Nanochromis. Based on a representative taxon sampling and well resolved phylogenetic hypotheses we demonstrate that a high level of riverine diversity originated in the lower Congo within about 5 mya, which is concordant with age estimates for the hydrological origin of the modern lower Congo River. A spatial genetic structure is present in all widely distributed lineages corresponding to a trisection of the lower Congo River into major biogeographic areas, each with locally endemic species assemblages. With the present study, we provide a phylogenetic framework for a complex system that may serve as a link between African riverine cichlid diversity and the megadiverse cichlid radiations of the East African lakes. Beyond this we give for the first time a biologically estimated age for the origin of the lower Congo River rapids, one of the most extreme freshwater habitats on earth. [ABSTRACT FROM AUTHOR]

The article presents a study on the Tilapia species flock of Lake Ejagham in Western Cameroon. The researchers used a digital caliper to take point-to-point measurements on the left side of the specimens, after which they used the statistical program PAST 1.98 to calculate the principal component analysis (PCA) of log-transformed morphometric data. They found that the PCA run of morphometric data of the subgenus Coptodon identified 14 taxa as discernible from Lake Ejagham. They also discussed the differences between two phenotypes of Tilapia fusiforme.

The article presents a study which examined the morphological structure and characteristics of the Gymnocephalus (G.) ambriaelacus, a new species of ruffe from Lake Ammersee in southern Germany. A phylogenetic analysis of both nuclear and mitochondrial sequence data of the new species were discussed by a unique nuclear LdhA6 intron haplotype. The ruffe of Lake Ammersee with G. cernua and G. baloni material were morphometrically and genetically compared from a wide variety of habitats and drainages. Results show that the landmark-based geometric morphometric approach using principal components analysis (PCA) based on the partial warp scores of three lake populations of G. cernua and new species were different despite similarity of ecological conditions influencing body shape.

Abstract: The Haplochromini are by far the most species-rich cichlid fish tribe that originated along with the so-called primary radiation of the Lake Tanganyika cichlid species flock, i.e. at the same time during which the majority of the endemic Lake Tanganyika cichlid tribes emerged. Unlike the other tribes, the haplochromines are not restricted to Lake Tanganyika but distributed throughout Africa, except for the northwestern part of the continent. Haplochromine cichlids seeded the adaptive radiation of cichlid fishes in Lakes Malawi, Kivu, Victoria, Turkana, as well as in the now extinct paleo-Lake Makgadikgadi. Here we present a comprehensive phylogenetic and phylogeographic analysis of haplochromine cichlids that is based upon DNA sequences of two mitochondrial gene segments of riverine taxa covering all major African biogeographic regions where haplochromines are found. Our analysis revealed that six lineages of haplochromines originated within a short period of time, about 5.3–4.4MYA. These haplochromine lineages show a highly complex phylogeographic pattern, probably severely influenced by climate- and/or geology-induced changes of the environment, with river capture events most likely playing an important role for species dispersal. [Copyright &y& Elsevier]