Melanie L. J. Stiassny

• PhD
• Professor at American Museum of Natural History

African cichlids comprise more than 1800 species of freshwater fishes, with remarkable adaptive radiations in Lakes Tanganyika, Malawi, and Victoria that have given rise to extraordinary morphological diversity. However, the evolution of the cichlid axial skeleton has been largely overlooked, despite its high variation and functional significance f...

Understanding the drivers of diversification is a central goal in evolutionary biology but can be challenging when lineages radiate quickly and/or hybridize frequently. Cichlids in the tribe Lamprologini, an exceptionally diverse clade found in the Congo basin, exemplify these issues: their evolutionary history has been difficult to untangle with p...

We describe the olfactory chamber and histology of the olfactory epithelium in the auchenoglanidid catfish, Parauchenoglanis punctatus. Unlike the olfactory anatomy of non-auchenoglanidid catfishes, in all auchenoglanidids the olfactory rosette is elevated on a membrane suspended over the anterior portion of a large accessory sac. Scanning electron...

Labeo niariensis sp. nov., a small‐sized Labeo species, is described from the Kouilou‐Niari River system in the Lower Guinean ichthyofaunal province. The species is a member of the newly erected Labeo annectens species group. Morphologically, it is distinguished from all congeners by the presence of a deeply bifurcate posterior process of the kinet...

We present the complete genome sequences of 20 species of African tetras, robbers, and tigerfishes in the families Alestidae, Hepsetidae, and Lepidarchidae. Illumina sequencing was performed on genetic material from wild-caught and aquarium specimens. The reads were assembled using a de novo method followed by a finishing step. The raw and assemble...

Freshwater ecosystems are highly biodiverse¹ and important for livelihoods and economic development², but are under substantial stress³. To date, comprehensive global assessments of extinction risk have not included any speciose groups primarily living in freshwaters. Consequently, data from predominantly terrestrial tetrapods4,5 are used to guide...

Geological evidence supports the occurrence of an epicontinental Trans-Saharan Seaway bisecting the African continent during the Late Cretaceous to early Palaeogene. The seaway formed a wide saltwater channel connecting the Neotethys with the South Atlantic, yet no previous study has investigated its impact on freshwater fish diversification. Phylo...

A new highly troglomorphic and diminutive swamp eel inhabiting muddy subsoil in remnants of a tropical rainforest in the Caribbean versant of Costa Rica is described. Comparative anatomical and mitogenomic data support the distinctiveness of the new species and its placement in the genus Ophisternon. The new species is unique among Neotropical cong...

Lamprologine cichlids are a diverse group of fishes distributed in Lake Tanganyika and the Congo River. Nine species of Lamprologus occur in the Congo River basin including the only blind cichlid Lamprologus lethops, but little is known about the natural history and evolution of this enigmatic species. To alleviate this knowledge gap, we characteri...

Synopsis Functional novelties play important roles in creating new ways for organisms to access resources. In fishes, jaw protrusion has been attributed to the massive diversity of suction-based feeding systems, facilitating the dominant mode of prey capture in this group. Nearly all fishes that feed by suction use upper jaw protrusion, achieved by...

Gene loss is an important mechanism for evolution in low-light or cave environments where visual adaptations often involve a reduction or loss of eyesight. The plaat gene family encodes phospholipases essential for the degradation of organelles in the lens of the eye. These phospholipases translocate to damaged organelle membranes, inducing them to...

Climatic and geomorphological changes during the Quaternary period impacted global patterns of speciation and diversification across a wide range of taxa, but few studies have examined these effects on African riverine fishes. The lower Congo River is an excellent natural laboratory for understanding complex speciation and population diversificatio...

A time-calibrated phylogeny, based on nuclear ultraconserved elements and including representatives of all major alestid lineages, strongly supports two distantly related clades within the currently accepted concept of Brycinus. The first, which includes the type species of the genus, B. macrolepidotus (herein Brycinus), and a second, composed of t...

We report the first record of Platyclarias machadoi Poll, 1977 since its original description. This species was sampled by electrofishing in rapids on the Kwanza River upstream of Capanda Dam in Angola. Morphomet-ric and meristic data for the Kwanza River material were compared to published data from the Platyclarias type series. Osteology was comp...

Labeo mbimbii, n. sp., and Labeo manasseeae, n. sp., two small-bodied Labeo species, are described from the lower and middle reaches of the Lulua River (Kasai ecoregion, Congo basin) in the Democratic Republic of Congo. The two new species are members of the L. forskalii species group and are genetically distinct from all other species of that clad...

Endeavours in species discovery, particularly the characterisation of cryptic species, have been greatly aided by the application of DNA molecular sequence data to phylogenetic reconstruction and inference of evolutionary and biogeographic processes. However, the extent of cryptic and undescribed diversity remains unclear in tropical freshwaters, w...

We review the systematics of the monotypic alestid genus Petersius and provide a taxo-nomic redescription of P. conserialis from eastern Tanzania. Morphological investigation includes direct observation and examination of radiographed and µCT-scanned data from type and non-type specimens. We delimit the taxon's geographic distribution along the low...

Characterizing functional freshwater biodiversity patterns and understanding community determinants can aid in predicting changes and prioritizing specific conservation management actions. Afrotropical freshwater systems support diverse ecological communities, including many taxonomically undescribed species, yet few studies have been undertaken in...

A new species of air-breathing catfish, Clarias monsembulai, is described from Congo River tributaries within and bordering the Salonga National Park (Democratic Republic of the Congo). The new taxon is recognized by its exceptionally long, white barbels, which lend a superficial resemblance to Clarias buthupogon, from which it differs in character...

African cichlids (subfamily: Pseudocrenilabrinae) are among the most diverse vertebrates, and their propensity for repeated rapid radiation has made them a celebrated model system in evolutionary research. Nonetheless, despite numerous studies, phylogenetic uncertainty persists, and riverine lineages remain comparatively underrepresented in higher-...

Labeo is the third most diverse genus of African cyprinids and is widely distributed across the continent. Labeo parvus, a small species originally described from the Congo basin, has been considered the only species of the L. forskalii group distributed across five African ichthyofaunal provinces (Nilo‐Sudan, Congo, Cuanza, and Upper and Lower Gui...

Freshwater fishes are notably diverse, given that freshwater habitat represents a tiny fraction of the earth’s surface, but the mechanisms generating this diversity remain poorly understood. Rivers provide excellent models to understand how freshwater diversity is generated and maintained across heterogeneous habitats. In particular, the lower Cong...

Despite the cultural and economic importance of fisheries to communities in the region, the Mfimi is one of the least well-documented river systems in the central Congo basin. Here we present a preliminary listing of species collected during two surveys sampling 35 sites along the main channel, in major tributaries, and in some marginal habitats. A...

Rivers provide excellent models to understand how species diversity is generated and maintained across heterogeneous habitats. The lower Congo River (LCR) consists of a dynamic hydroscape exhibiting extraordinary aquatic biodiversity, endemicity, and ecological specialization. Previous studies have suggested that the numerous high-energy rapids thr...

Two new Phenacogrammus are described from the Ndzaa River, a small left-bank tributary of the Mfimi-Lukenie River in the central Congo basin. They share with P. deheyni, a congener endemic to the Cuvette Centrale to the north, a prominent anterior expansion of the first pleural rib; a feature interpreted here as a synapomorphy diagnostic for this s...

More than 40 years ago in their compendium of fish diversity in the lower Congo River (LCR), T. R. Roberts and D. J. Stewart posed the question, “Why does the LCR harbor so many cichlids?” Here we seek an answer through a synthesis of the last 40+ years of research on cichlid diversity, ecology, and speciation. Our review suggests a key role for th...

The ichthyofauna of the Lulua River, a large right bank tributary of the Kasai River in central Africa, is among the most poorly documented in the Kasai ecoregion. To remedy this lack of knowledge, sampling was carried out between 2007 and 2014 along the main channel and in many tributaries. A total of 201 species distributed in 81 genera, 24 famil...

Labeo sorex is a carp species endemic to the Congo River (CR) where it mainly occurs in rapids habitats. The species has been described from the Wagenia Falls at Kisangani, Oriental Provence, Democratic Republic of the Congo and from the lower Congo River (~1800 km downstream). The species is characterized as highly adapted to rapid habitats (rheop...

The Neotropics harbor the most species-rich freshwater fish fauna on the planet, but the timing of that exceptional diversification remains unclear. Did the Neotropics accumulate species steadily throughout their long history, or attain their remarkable diversity recently? Biologists have long debated the relative support for these museum and cradl...

Available ecological information, an extensive distributional range, conflicting osteological data, and a proposed early Miocene origin provide the impetus for the present study which investigates genetic structuring, biogeographic, and phylogenetic relationships within the Aplocheilichthys spilauchen lineage. Through the analysis of the mitochondr...

Background: Distichodus is a clade of tropical freshwater fishes currently comprising 25 named species distributed continent-wide throughout the Nilo-Sudan and most Sub-Saharan drainages. This study investigates the phylogenetic relationships, timing of diversification, and biogeographic history of the genus from a taxonomically comprehensive muti...

Trait loss represents an intriguing evolutionary problem, particularly when it occurs across independent lineages. Fishes in light-poor environments often evolve "troglomorphic" traits, including reduction or loss of both pigment and eyes. Here we investigate the genomic basis of trait loss in a blind and depigmented African cichlid, Lamprologus le...

Background: Distichodus is a clade of tropical freshwater fishes currently comprising 25 named species distributed continent-wide throughout the Nilo-Sudan and most Sub-Saharan drainages. This study investigates the phylogenetic relationships, timing of diversification, and biogeographic history of the genus from a taxonomically comprehensive mutil...

Background: Distichodus, the type genus of the endemic African characiform family Distichodontidae, is a clade of tropical freshwater fishes currently comprising 25 named species distributed continent-wide throughout the Nilo-Sudan and most Sub-Saharan drainages. This study investigates the phylogenetic relationships, timing of diversification, and...

Background : Distichodus is a clade of tropical freshwater fishes currently comprising 25 named species distributed continent-wide throughout the Nilo-Sudan and most Sub-Saharan drainages. This study investigates the phylogenetic relationships, timing of diversification, and biogeographic history of the genus from a taxonomically comprehensive muti...

Background : Distichodus is a clade of tropical freshwater fishes currently comprising 25 named species distributed continent-wide throughout the Nilo-Sudan and most Sub-Saharan drainages. This study investigates the phylogenetic relationships, timing of diversification, and biogeographic history of the genus from a taxonomically comprehensive muti...

A new species of the chromidotilapiine genus Thysochromis, is described from the Noumbi and Kouilou River drainages in the Republic of Congo. Based on the current investigation, Thysochromis is resolved as containing two geographically disjunct species, T. ansorgii from localities in the upper Guinean ichthyofaunal province (Ivory Coast, Ghana, Ben...

A new procatopodid, assigned to the genus Poropanchax, is described from a wetland habitat located adjacent to the Inga Falls in Lower Congo. Poropanchax pepo, new species, is distinguished from all congeners by a combination of characters including a higher D/A ratio, rounded anal and dorsal fins, a humeral blotch in males, and the absence of a sh...

A new procatopodid, assigned to the genus Poropanchax, is described from a wetland habitat located adjacent to the Inga Falls in Lower Congo. Poropanchax pepo, new species, is distinguished from all congeners by a combination of characters including a higher D/A ratio, rounded anal and dorsal fins, a humeral blotch in males, and the absence of a sh...

To investigate the presence of cryptic diversity in the African longfin‐tetra Bryconalestes longipinnis, we employed DNA barcoding in a phylogeographic context, as well as geometric morphometrics, documenting for the first time genetic and body shape variation in the species. Analysis of cytochrome oxidase I gene (coI) sequence variation exposed ex...

Although the majority of cichlid diversity occurs in the African Great Lakes, these fish have also diversified across the African continent. Such continental radiations, occurring in both rivers and lakes have received far less attention than lacustrine radiations despite some members, such as the oreochromine cichlids (commonly referred to as ‘til...

A new species of smiliogastrin cyprinid is described from the Louesse, Lekoumou (upper Niari basin), and Djoulou (upper Ogowe basin) rivers in the Republic of Congo, west-central Africa. The new species is readily distinguished from congeners by the presence of a flexible, weakly ossified and smooth bordered last unbranched dorsal-fin ray, well-dev...

The historical focus of research on temperate freshwater systems has resulted in a large data gap in the tropics, particularly in Afrotropical regions. As most conceptual models have been developed in temperate systems, their applicability to Afrotropical waters is uncertain. The aim of this study is to use trait and diversity information from fres...

The Danakil Depression of northeastern Africa is among the harshest environments on Earth. Yet, despite extreme aridity, this desert region hosts the endemic cichlid genus Danakilia. As currently recognized, the genus includes at least two populations of Danakilia franchettii from groundwater springs feeding Lake Afrera (Ethiopia), one population o...

The Danakil Depression in northeastern Africa represents one of the harshest arid environments on Earth, yet two genera of fishes, Danakilia (Cichlidae) and Aphanius (Cyprinodontidae), share its sparse aquatic habitats. The evolutionary history of these fishes is investigated here in the context of genetic, geological and paleoenvironmental informa...

Table S1. Principal physical and chemical parameters of water sampled at different locations in the Danakil Depression. Table S2. Summary of evolutionary models applied to Danakilia and Aphanius for phylogenetic inference.

Morphological asymmetry is described in the heterenchelyid mud eel Pythonichthys cf. macrurus from inshore coastal waters of Guinea, West Africa. The intensity of asymmetry differs between two examined specimens, with the more extreme case exhibiting strong asymmetry in both external and internal features, including unilateral depigmentation, reduc...

Aim There has been recent interest in the origin and assembly of continental biotas based on densely sampled species‐level clades, however, studies from African freshwaters are few so that the commonality of macroevolutionary patterns and processes among continental clades remain to be tested. Within the Afrotropics, the Congo Basin contains the hi...

Ostariophysi is a superorder of bony fishes including more than 10,300 species in 1100 genera and 70 families. This superorder is traditionally divided into five major groups (orders): Gonorynchiformes (milkfishes and sandfishes), Cypriniformes (carps and minnows), Characiformes (tetras and their allies), Siluriformes (catfishes), and Gymnotiformes...

Much progress has been achieved in disentangling evolutionary relationships among species in the tree of life, but some taxonomic groups remain difficult to resolve despite increasing availability of genome-scale data sets. Here we present a practical approach to studying ancient divergences in the face of high levels of conflict, based on explicit...

The lower Congo River (LCR) is a freshwater biodiversity hotspot in Africa characterized by some of the world's largest rapids. However, little is known about the evolutionary forces shaping this diversity, which include numerous endemic fishes. We investigated phylogeographic relationships in Teleogramma, a small clade of rheophilic cichlids, in t...

Xenocharax crassus Pellegrin, 1900, originally described from the Alima River (Congo basin, Republic of Congo) but synonymised with X. spilurus by Daget in 1960, is rehabilitated. Xenocharax crassus, a Congo basin endemic, is distinguished from X. spilurus, the latter found exclusively in basins of the Lower Guinean ichthyofaunal province, by the p...

The question whether taxonomic descriptions naming new animal species without type specimen(s) deposited in collections should be accepted for publication by scientific journals and allowed by the Code has already been discussed in Zootaxa (Dubois & Nemésio 2007; Donegan 2008, 2009; Nemésio 2009a–b; Dubois 2009; Gentile & Snell 2009; Minelli 2009;...

This plot is not part of the published stance but derives from it. The plot shows the number of authors by geographic region (courtesy of Dr. Diego Astua).

The Congo River is the second only to the Amazon in terms of size and freshwater species diversity. The basin covers 4 million km2. The basin has over 1200 fish species, 400 mammal species, 1,000 bird species and over 10,000 vascular plant species. It provides about 30 % of Africa’s freshwater resources, and about 77 million people living in the Co...

The Congo River is the second only to the Amazon in terms of size and freshwater species diversity. The basin covers 4 million km2. The basin has over 1200 fish species, 400 mammal species, 1,000 bird species and over 10,000 vascular plant species. It provides about 30 % of Africa’s freshwater resources, and about 77 million people living in the Co...

A survey of the ichthyofauna of the Geebo-Dugbe watershed in Sinoe County, Liberia was undertaken in anticipation of future economic developments. The watershed lies between Sapo National Park and the Grand Kru-River Gee National Forest and is believed to serve as a wildlife corridor between the two preserves. Small first or second order streams pr...

A new species of smiliogastrin cyprinid is described from tributaries of the middle Congo River in the Democratic Republic of Congo. Restriction of the genus name, Barbus, to certain large-bodied, (polyploid) barbins, and current uncertainty regarding phylogenetic relationships among the numerous small-bodied African (diploid) barbs, renders generi...

A revised diagnosis for the smiliogastrin genus Clypeobarbus is provided and a new species, Clypeobarbus breviclipeus, from the Kwilu River (Kasai Basin) of central Africa, is described. Another species co-occurring in the Kwilu system, 'Barbus' matthesi, shares all diagnostic morphological synapomorphies of Clypeobarbus and its generic reassignmen...

Basin-scale planning is needed to minimize impacts in mega-diverse rivers

Xenocharax crassus Pellegrin, 1900, originally described from the Alima River (Congo basin, Republic of Congo) but synonymised with X. spilurus by Daget in 1960, is rehabilitated. Xenocharax crassus, a Congo basin endemic, is distinguished from X. spilurus, the latter found exclusively in basins of the Lower Guinean ichthyofaunal province, by the p...

Background The lower Congo River (LCR) is a region of exceptional species diversity and endemism in the Congo basin, including numerous species of spiny eels (genus Mastacembelus ). Four of these exhibit distinctive phenotypes characterized by greatly reduced optic globes deeply embedded into the head (cryptophthalmia) and reduced (or absent) melan...

The dwarf seahorse (Hippocampus zosterae) is widely distributed throughout near-shore habitats of the Gulf of Mexico and is of commercial significance in Florida, where it is harvested for the aquarium and curio trades. Despite its regional importance, the genetic structure of dwarf seahorse populations remains largely unknown. As an aid to ongoing...

Rosemary Helen Lowe-McConnell was born in Liverpool on 24 June 1921 and died peacefully on 22 December 2014 at St. George’s Park, Ditchling, England. Despite declining health “Ro”, as friends and colleagues around the globe knew her, retained her fabulous sense of humor and famously generous good spirits, graciously entertaining a steady stream of...

The lower Congo River and nearby habitats harbor numerous endemic lineages of cichlid fishes, including some with highly specialized morphologies. based on morphological and molecular data, we herein describe a new species of Teleogramma, a member of the chromi-dotilapiine clade found on rocky outcrops in the lower reaches of the middle Congo River...

DNA barcoding was used to investigate dietary habits and prey selection in members of the African-endemic family Distichodontidae noteworthy for displaying highly specialized ectoparasitic fin-eating behaviors (pterygophagy). Fin fragments recovered from the stomachs of representatives of three putatively pterygophagous distichodontid genera (Phago...

A new Lamprologus is described from the lower Congo River (LCR) in the Democratic Republic of Congo. Lamprologus markerti, new species, is readily distinguished from L. tigripictilis and L. werneri, the LCR endemic lamprologines with which it was once taxonomically conflated, in the possession of a reduced number of gill rakers on the first arch (9...

Fishes of the order Characiformes are a diverse and economically important teleost clade whose extant members are found exclusively in African and Neotropical freshwaters. Although their transatlantic distribution has been primarily attributed to the Early Cretaceous fragmentation of western Gondwana, vicariance has not been tested with temporal in...

A list of fishes collected in the N’sele River, a large affluent tributary of Pool Malebo, in the Democratic Republic of Congo is provided. Sites along the main channel and its affluent tributaries were sampled and 148 species distributed in 27 families are reported. Despite close proximity to the megacity of Kinshasa, the ichthyofauna of the N’sel...

Lake Tanganyika is known for the endemicity of its fishes and species flocks of cichlids, Lates, mochokid catfishes and mastacembelid spiny eels. While the term “species flock” is sometimes applied to Tanganyika’s claroteine catfishes, the number of lineages represented among them and their extra-lacustrine affinities was unknown. Tanganyikan claro...

A new species of ectoparasitic distichodontid, Eugnathichthys virgatus, is described from localities in the central and western Congo basin. The new species is a fin-eater even at small sizes and, in common with congeners, is capable of biting off sections of heavily ossified fin-rays of large prey species. Prior to the present study, two species w...

A list of fishes collected in and around the periphery of the Salonga National Park in Equateur Province of the Democratic Republic of Congo is provided. While noteworthy for a wide array of rare and endangered terrestrial vertebrates, the fish fauna of the Salonga National Park, the largest protected area in Africa, is very poorly known. One hundr...

A list of fishes collected in rivers of the Du Chaillu Massif, Niari Depression, and Mayombe Massif in the Republic of Congo is provided. Few previous collections have been made and the region is poorly known ichthyologically, however several large mining projects are under development while logging and artisanal gold mining is already underway. On...

Objective: Troglomorphic fishes provide excellent comparative models for studying eye evolution. We describe the gross and microscopic anatomy of ocular structures of the depigmented, blind cichlid, Lamprologus lethops, and its putative sister species, Lamprologus tigripictilis collected from the lower Congo River in the Democratic Republic of Con...