Revision of the cichlid fish genus Gnathochromis (Teleostei: Cichlidae) from Lake Tanganyika with the description of a new genus Jabarichromis gen. nov.

The cichlid species flock from Lake Tanganyika is a well-studied system for evolutionary biology research because its species assemblage shows a high degree of endemism and is a product of adaptive radiation. While our understanding of the evolutionary history of Lake Tanganyika cichlids has advanced tremendously over the past decades, their taxonomy received considerably less attention, despite numerous taxonomic misplacements (e.g., polyphyletic genera and species) that have been revealed by phylogenetic studies. One prominent example of a polyphyletic genus is Gnathochromis, which includes two distantly related species, belonging to two different tribes. To resolve this issue, here we present a taxonomic revision based on an extensive morphological dataset obtained from a comprehensive taxon sampling including 587 specimens from 63 taxa. We introduce a new monotypic genus, Jabarichromis gen. nov. for Gnathochromis pfefferi, a member of the tribe Tropheini, thereby separating it from the type species of Gnathochromis, G. permaxillaris. As a result, the genus Gnathochromis, which belongs to the tribe Limnochromini, is rendered monophyletic. Further, we provide an additional character to distinguish the recently described genus Shuja, which also belongs to the Tropheini, from its former mostly riverine congeners.

Cryptic persistence and loss of local endemism in Lake Constance charr subject to anthropogenic disturbance.

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.

A new Parakneria Poll 1965 (Gonorhynchiformes: Kneriidae), 'Mikinkidi' from the Upper Lufira Basin (Upper Congo: DRC): Evidence from a morphologic and DNA barcoding integrative approach.

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.

Towards the phylogenetic placement of the enigmatic African genus Prolabeops Schultz, 1941.

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.

Congochromis rotundiceps sp. nov., a new cichlid species (Actinopterygii: Cichlidae) from the Congo Drainage.

A new dwarf cichlid, Congochromis rotundiceps sp. nov., (Cichliformes: Cichlidae) is described from the central Congo basin. It is a species of Congochromis based on the following characters: (1) four pores in the dentary laterosensory canal; (2) absence of a laterosensory canal in the angulo-articular, (3) six pores in the preopercle laterosensory canal; (4) a single tubular infraorbital bone behind the lachrymal; (5) 12 circumpeduncular scales; (6) jaw teeth comparatively robust, unicuspids, not closely spaced; and (7) presence of a small, supraneural bone. Congochromis rotundiceps sp. nov. is distinguished from all other Congochromis species by the combination of the following characters: (1) a larger eye diameter (31.435.1% HL), (2) a shorter snout length (29.832.7% HL), (3) a shorter upper lip length (29.232.0% HL), (4) a shorter lower lip length (26.233.6% HL), (5) a shorter lower lip width (27.731.2% HL), and (6) a shorter anal-fin length (15.316.97% SL). Diagnostic characters were extracted mainly from meristic counts and distance measurements from 326 chromidotilapiine cichlid specimens representing all chromidotilapiine genera and 40 described or undescribed species. The analysis of the complete meristic and distance measurements database allowed the diagnosis of C. rotundiceps sp. nov., but not for diagnostic separation of many other chromidotilapiine genera, species, and lineages. This result highlights the necessity to explore additional characters to elucidate chromidotilapiine cichlid taxonomy further.

New phylogenetic insights into the African catfish families Mochokidae and Austroglanididae.

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.

Palaeoplex gen. nov. and Lufubuchromis gen. non, two new monotypic cichlid genera (Teleostei: Cichlidae) from northern Zambia.

Two monotypic haplochromine cichlid genera (Teleostei: Cichlidae) of the Pseudocrenilabrus group are described from northern Zambia. One new genus is Palaeoplex gen. nov., with Pa. palimpsest sp. nov. as the type species, from the Luongo and Kalungwishi Rivers (Upper Congo drainage, Luapula subdrainage). It is diagnosed by a unique combination of morphological characters: (1) a fully developed infraorbital series without a distinct gap between the lachrymal and second infraorbital bone, (2) fused hypuralia 1+2 and hypuralia 3+4, (3) molariform teeth on the sagittal series of the lower pharyngeal jaw, and (4) a large maximum size. The second new genus, Lufubuchromis gen. nov., with L. relictus sp. nov. as the type species, is restricted to the upper Lufubu River catchment (Upper Congo drainage, Lake Tanganyika subdrainage). It is diagnosed by a unique combination of morphological characters: (1) a fully developed infraorbital series without a distinct gap between the lachrymal and second infraorbital bone, (2) fused hypuralia 1+2 (rarely with a visible suture) and fused hypuralia 3+4, (3) a unique male coloration pattern, i.e. deep crimson red colored areas on the anterior ventral flank parts, chest and belly and on the lower head; remaining parts of flanks and caudal peduncle bluish), and (4) a Pseudocrenilabrus blotch present in both sexes. Both new genera are compared with all remaining taxa of the Pseudocrenilabrus group and with all representatives of all other major haplotilapiine lineages.