Search

Examination of the holotype of Synodontis nigrita, the type specimens of both its (potential) junior synonyms, Synodontis fascipinna and Synodontis ornatus, and an additional 306 specimens, previously identified as S. nigrita, confirmed that the interorbital width is the most important diagnostic character to distinguish S. nigrita from its Nilo‐Sudanic (N‐S), and Upper and Lower Guinea ichthyofaunal province congeners. Results revealed that this species has a typical N‐S distribution. In addition, the occurrence of Synodontis violaceus in the Cross River is not corroborated. Therefore, it should be considered a typical West African species. [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 chubbyhead barb, Enteromius anoplus, as currently described, is the most widely distributed freshwater fish in South Africa. The species occurs in almost all the major river systems across the country, with the exception of the small coastal drainages on the south coast. The use of a comprehensive data set of mitochondrial (mtDNA) cytochrome b (cyt b) sequences uncovered the presence of four distinct lineages or operational taxonomic units (OTUs) within E. anoplus: (a) the Gouritz lineage endemic to the Gouritz River system, (b) the Olifants lineage endemic to the Olifants‐Doring River system, (c) the Orange lineage endemic to the Orange River system and (d) the Eastern Cape lineage which is distributed across six river systems from the Great Fish to the Buffalo rivers in the Eastern Cape Province of South Africa. The present study provides a new diagnosis for E. anoplus s.s. (the Gouritz lineage), revalidates Enteromius cernuus (the Olifants lineage) and Enteromius oraniensis (the Orange lineage) as distinct species. The study also provides a description for a new species, Enteromius mandelai sp. nov (the Eastern Cape lineage). E. cernuus and E. mandelai differ from both E. anoplus and E. oraniensis by having a complete lateral line (vs. an incomplete lateral line in the latter species). E. cernuus further differs from the other three species by having long maxillary barbels which reach or exceed the vertical through the middle of the eye and the lowest number of circumpendicular scales (10–12 vs. 12–16 for the other three species). E. oraniensis is distinctive from the other three species by having inconspicuous barbels. These findings add to the growing body of literature that shows that the freshwater fishes of the Cape Fold and adjacent freshwater ecoregions have narrow geographic ranges. This has ramifications for conservation planning and management, as well as the understanding of the evolutionary history of the stream fishes in these global endemic hotspots. [ABSTRACT FROM AUTHOR]

Aside from ornamental uses, there is growing interest in using killifishes for a multiplicity of purposes including baitfish and mosquito biocontrol. This experiment explored the spawning habits and embryonic development of the banded lampeye, Aplocheilichthys spilauchen in ex situ freshwater (0.04‰) and brackish water (5.01‰) to ascertain the captive breeding prospects for mosquito control in areas where they occur. Significantly higher number of eggs were laid in the brackish water than the freshwater (X2 = 1613.0, P < 0.05), and black mop was the most preferred spawning substrate, followed by green, blue and white mops. Microscopic monitoring of embryos revealed that cleavage occurred within the first 30 min after fertilization, organogenesis commenced on average in the 25th hour and hatching in approximately 230 h. Although freshwater eggs were relatively bigger than brackish water eggs and certain embryonic developmental stages occurred faster in the freshwater than brackish water, these differences were overall not significant and had no effects on the development and hatching. The observed outcome that A. spilauchen can be optimally propagated with black mops in brackish water offers a significant step in its use for the mosquito biocontrol programme, as well as other potential uses not yet explored. [ABSTRACT FROM AUTHOR]

Based on literature, museum collections and three recent expeditions, an annotated species list of the Lake Edward, East Africa, drainage system is presented, excluding the endemic haplochromines. A total of 34 non‐Haplochromis species belonging to 10 families and 21 genera are recorded from the system. Three of these are endemic and two others have been introduced in the region. Six species are new records for the Lake Edward system. A species accumulation curve indicates that we probably covered most of the non‐Haplochromis species in the area sampled during the recent expeditions, but undetected species might still be present in the Congolese part of the system, which is poorly sampled. A comparison of the species list with those of neighbouring basins confirmed the placement of the Lake Edward system within the east‐coast ichthyofaunal province. [ABSTRACT FROM AUTHOR]

Within a comparative morphological framework, Hippopotamyrus aelsbroecki, only known from the holotype originating from Lubumbashi, most probably the Lubumbashi River, a left bank subaffluent of the Luapula River, is reallocated to the genus Cyphomyrus. This transfer is motivated by the fact that H. aelsbroecki possesses a rounded or vaulted predorsal profile, an insertion of the dorsal fin far anterior to the level of the insertion of the anal fin, and a compact, laterally compressed and deep body. In addition, a new species of Cyphomyrus is described from the Lufira basin, Cyphomyrus lufirae. Cyphomyrus lufirae was collected in large parts of the Middle Lufira, upstream of the Kyubo Falls and just downstream of these falls in the lower Lufira and its nearby left bank affluent, the Luvilombo River. The new species is distinguished from all its congeners, that is, firstly, from C. aelsbroecki, C. cubangoensis and C. discorhynchus, by a low number of dorsal fin rays, 27‐32 (vs. higher, 36 (37), 34 (33‐41) an 38 (38‐40), respectively) and, secondly, from C. aelsbroecki, C. cubangoensis, and C. discorhynchus by a large prepelvic distance, 41.0–43.8% LS (vs. shorter, 39.7%, 38.9–39.1% and 37.0–41.0% LS, respectively). The description of yet another new species for the Upemba National Park and the Kundelungu National Park further highlights their importance for fish protection and conservation in the area. Hence, there is an urgent need for the full integration of fish into the management plans of these parks. [ABSTRACT FROM AUTHOR]

New collections from the Yangambi Biosphere Reserve (YBR) and Okapi Wildlife Reserve (OWR) revealed the presence of two groups of specimens similar to, but different from Marcusenius moorii. To study both these groups, an integrated morphological and genetic (mtDNA, cytb) approach was used. This study revealed that one of the two groups is conspecific with Marcusenius lambouri, a junior synonym of M. moorii, which is herein revalidated, with M. mooriilongulus as its junior synonym. Marcusenius lambouri differs from M. moorii by a higher number of lateral line scales (44–46 vs. 40–43), a shorter pectoral‐fin length (14.6–19.9 vs. 20.3–25.2% standard length; LS) and a more elongated body due to a usually shallower middle body depth (19.8–26.5 vs. 26.3–35.9% LS). The other group revealed to be a new species for science, Marcusenius verheyenorum, which can be distinguished from its congeners with eight circumpeduncular scales by the following unique combination of characters: a rounded head with a terminal mouth; a short and deep caudal peduncle (middle caudal‐peduncle depth, 44.9–54.6% caudal‐peduncle length; LCP), a deep body (middle body depth, 27.7–34.2% LS), 38–43 scales on the lateral line, 40–41 vertebrae, 20–21 dorsal‐fin rays and 26 anal‐fin rays. Some specimens previously attributed to M. moorii were examined and reassigned to M. lambouri or M. verheyenorum. As a result, M. moorii and M. lambouri occur in sympatry in the middle Congo Basin, with the distribution area of M. moorii still further extending into the lower Congo Basin. Instead, the distribution of M. verheyenorum is limited to some right bank tributaries of the upstream part of the middle Congo Basin. Two museum records from the Lilanda River (YBR), collected in the 1950s and previously identified as M. moorii, were re‐identified as belonging to the new species, M. verheyenorum. However, the species now seems locally extinct in that region, which reflects the significant anthropogenic effects even within this reserve. [ABSTRACT FROM AUTHOR]

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, Benin and Nigeria) and Thysochromis emili sp. nov. restricted to coastal regions of the Republic of Congo in the lower Guinean province. [ABSTRACT FROM AUTHOR]

The Kahuzi‐Biega National Park (KBNP), situated mainly in the Eastern Highlands Ecoregion of the Upper Congo basin, is drained by the Lowa and Ulindi rivers, and some western affluents of Lake Kivu. In this study, the first list of the fish diversity of these systems is provided based on museum collections and complemented, for the Lowa River system and the western Lake Kivu affluents, with recently collected specimens (2013–2017). A total of 118 species are reported from the Lowa basin, 22 from the Ulindi basin and seven from these Lake Kivu affluents. Within the Lowa and Ulindi, respectively, five and one species, all cichlids, have been introduced. Currently, 51 species are reported from within the park, only two of which have been reported from the highlands, i.e., Amphilius kivuensis from the Luha, the source of the Luka River, and Clarias liocephalus from the headwaters of the Lake Kivu' affluents. With a total of 30 species, Cyprinidae is by far the largest family, representing 25% of the total species diversity of the Lowa basin. It is followed by Mormyridae with 13 species (11%), Alestidae and Mochokidae with 10 species each (8%), Clariidae and Amphiliidae with eight species (7%), and Distichodontidae with six species (5%). Seven new species for science were discovered and 11 species were found to be endemic to the Lowa system. Although further exploration is needed, this underscores the importance of the KBNP in protecting the fish fauna of the Lowa basin but also highlights the park's limited coverage of the fish fauna of the Lowa basin. [ABSTRACT FROM AUTHOR]

The present study assessed the aerial and aquatic visual abilities of juvenile grey bichir Polypterus senegalus, fish capable of terrestrial locomotion, by measuring the optokinetic response to stimuli of varying speed and spatial frequency. In water, fish tracked slow‐moving (2° s−1) stimuli moderately well and fast‐moving stimuli very poorly. Spatial acuity was very low compared with many other species, with maximum response observed at 0.05–0.075 stimulus cycles per degree of visual arc; however, it should be noted that adult fish, with their larger eyes, are likely to have somewhat improved spatial acuity. Low spatial acuity and limited stimulus tracking ability might be expected in a nocturnal ambush predator such as P. senegalus, where gaze stabilization may be less crucial and other sensory inputs may have greater importance in perception of the environment. In air, spatial and temporal acuity were both poorer by every measure, but some visual ability persisted. As the eye shows no anatomical specialization for aerial vision, poor vision was expected; however, the large decrease in saccade velocity observed in air trials was unexpected. Stimulus parameters typically have little effect on the characteristics of the saccade, so this finding may suggest that the function of the reflex system itself could be compromised in the aerial vision of some fishes capable of terrestrial locomotion. [ABSTRACT FROM AUTHOR]

Two new species of Tometes from the Brazilian Shield rapids are described. Tometes kranponhah is endemic to the Xingu River basin, whereas Tometes ancylorhynchus occurs both in the Xingu and the Tocantins-Araguaia River basins. The two species are sympatric in the Xingu drainages and have many similarities in morphology and colouration. Major diagnostic differences are the dark pigmentation on the opercle of T. kranponhah and its distinct snout shape and arrangement of premaxillary teeth. In addition, T. kranponhah is a large fish that is abundant in the Xingu River, whereas T. ancylorhynchus is a medium-sized fish for which there are few records. [ABSTRACT FROM AUTHOR]

A new species of deep-living dragonet Callionymus omanensis from Oman is described on the basis of a single male specimen collected in a trawl from 500 m depth off the coast of Oman. The new species is characterized within the subgenus Bathycallionymus by having a small branchial opening; head short (3·9 in proportion to standard length); eye large (2·4 in proportion to head length); preopercular spine with a long, upcurved main tip, with a small antrorse barb and a larger antrorse spine, and with a strong antrorse spine laterally at the preopercular-spine base, ventral margin smooth; first dorsal fin slightly higher than second dorsal fin (male); second dorsal fin distally straight; 17 pectoral fin rays; distal end of caudal fin slightly pointed, with two median unbranched rays bearing short filaments; first dorsal fin with basal black spot reaching from first to fourth membranes, third membrane with an ocellated distal black blotch; second dorsal fin with vertical dark grey bars; distal three-fourths of anal fin black; upper half of caudal fin with oblique dark grey bars; pelvic fin dark grey, second ray basally with a black blotch. The new species is compared with similar species. Revised keys to callionymid species of the western Indian Ocean and the Red Sea, as well as species of the subgenus Bathycallionymus, are presented. [ABSTRACT FROM AUTHOR]