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Principal component analysis for anatomy of Petrocephalus okavangensis sp. nov. (red triangles) from (A, B) Guma Lagoon (n = 45) and (C, D) Popa Rapids (n = 36), compared with (A, C) P. longicapitis sp. nov. from Upper Zambezi River (blue squares) and (B, D) P. magnoculis sp. nov. (blue squares). Upper panels, analyses on 13 characters (see Table 3), lower panels, analyses on 17 characters (see Table 1, with HL/Na and LSc/HL excluded). Prin1-Prin3, for Principal Components 1-3.
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We morphologically and genetically studied the southern African electric fish Petrocephalus catostoma, or churchill, and its six nominal species, five of which by synonymization (three valid subspecies). We reinstate the synonymized species, and recognize Petrocephalus tanensis (Whitehead and Greenwood, 195982.
Whitehead , PJ and
Greenwood , PH....
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Context 1
... of the latter two were differentiated from the two samples of the Okavango River proper: Guma and Popa. This is shown by non-overlapping ranges in PC1-PC3 coordinates, inde- pendent of whether the Okavango River was represented by the Guma Lagoon sample ( Figure 5A, B) or the Popa Rapids sample ( Figure 5C, D). ...
Context 2
... of the latter two were differentiated from the two samples of the Okavango River proper: Guma and Popa. This is shown by non-overlapping ranges in PC1-PC3 coordinates, inde- pendent of whether the Okavango River was represented by the Guma Lagoon sample ( Figure 5A, B) or the Popa Rapids sample ( Figure 5C, D). ...
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Citations
... In addition, original descriptions and associated systematic literature (i. e., generic revisions) were consulted for identification of diagnostic characteristics to identify specimens of hard to determine species: e.g., for Amphilius Günther 1864(Thomson, 2013Thomson et al., 2015), Chiloglanis Peters 1868 (Ng and Bailey, 2006), Enteromius paludinosus (Peters, 1852) species complex (Englmaier et al., 2020), various alestid genera (Paugy, 1986), Nannocharax Günther, 1867(Bragança et al., 2020a, Hepsetus Swainson, 1838, Petrocephalus Marcusen, 1854(Kramer et al., 2012Lavoué, 2012), African lampeyes (Bragança et al., 2020b), Zaireichthys Roberts, 1968(Eccles et al., 2011. In some cases, specimens could not be assigned to any described species and hence are here referred to as candidate species, following the terminology of potentially undescribed species (Padial et al., 2010;Vieites et al., 2009). ...
In contrast to the fish diversity of the African Great Lakes, in particular cichlid fishes, the ichthyofauna of most river systems in Africa is poorly documented and remains critically understudied. Here we focus on the fish fauna of Northern Zambia, a region that is located between two African Great Lakes and covers the contact zones between three major drainage systems: the Zambezi drainage system, the Congo drainage system, including the Lake Tanganyika catchment and the Lake Rukwa drainage system. Our study contributes to the taxonomic knowledge of this region by providing DNA barcodes (COI) of 315 newly acquired museum voucher specimens representing approximately 125 species, together with distribution details of these species as well as those for which no barcodes have been obtained during this study. The barcoding efforts focused mainly on the fish fauna of the Luangwa River and its tributaries, the Lufubu River, the Upper Chambeshi, the Saisi River and included some Lake Malawi affluents as well. In total, 147 fish species, distributed over 16 families and 46 genera, were recorded from 38 sampling locations. A large proportion of these species appear to be undescribed. This is best exemplified by the fish fauna of the Lufubu River, where of the 37 species recorded, 25 represent candidate species putatively endemic to the system. This first step to establish a DNA barcode library for the freshwater fish diversity of Northern Zambia will serve as valuable tool for the taxonomic inventory of this region as well as for future conservation actions.
... Petrocephalus degeni is a small mormyrid (standard length of 8.1 cm, Kramer et al. 2012) reported from sites within the Lake Victoria basin of East Africa (Ogutu-Ohwayo 1993;Chapman et al. 1996;Kramer et al. 2012). Weakly electric mormyrid fish generate an electric field around their body by discharging their electric organ (Lissmann 1951), which they use to navigate and forage without relying on their visual sense (Lissmann 1958;Lissmann and Machin 1958) and to communicate with conspecifics (Moller 1970;Moller and Bauer 1973). ...
... Petrocephalus degeni is a small mormyrid (standard length of 8.1 cm, Kramer et al. 2012) reported from sites within the Lake Victoria basin of East Africa (Ogutu-Ohwayo 1993;Chapman et al. 1996;Kramer et al. 2012). Weakly electric mormyrid fish generate an electric field around their body by discharging their electric organ (Lissmann 1951), which they use to navigate and forage without relying on their visual sense (Lissmann 1958;Lissmann and Machin 1958) and to communicate with conspecifics (Moller 1970;Moller and Bauer 1973). ...
Hypoxia is a widespread environmental stressor that shapes fish physiology and morphology. Plasticity in traits that improve oxygen uptake and delivery or reduce oxygen requirements may be critical for fish to cope with fluctuating dissolved oxygen (DO) conditions in their natural habitat or adapt to new environments. In this study, we characterized a suite of morpho-physiological respiratory traits of a naturally hypoxia-acclimated weakly electric mormyrid fish, Petrocephalus degeni, and quantified their plasticity in response to long-term normoxia exposure. We captured P. degeni from a hypoxic swamp habitat (PO2 = 2.43 ± 1.85 kPa) surrounding Lake Nabugabo, Uganda, and acclimated them to normoxia (PO2 > 16 kPa) for up to 75 days. At various time points throughout normoxia exposure, we measured blood hemoglobin and lactate concentration, gill size, routine metabolic rate (RMR), regulation index (RI), and critical oxygen tension (Pcrit). We found that 62–75 days of normoxia exposure significantly reduced blood hemoglobin concentration (− 17%), gill filament length (− 14%), and hemibranch area (− 18%), whereas RMR, RI, Pcrit, and blood lactate showed no significant change. Our results support earlier findings that swamp-dwelling P. degeni are well adapted to life in chronic and severe hypoxia and indicate that they possess a limited capacity for phenotypic plasticity in response to a change in their DO environment.
... 2022). However, recent studies have shown that this species is native to the Zambezi ichthyofaunal province (Kramer et al., 2012). Being a riverine species, this new evidence suggests that presence of this species in Uganda is unlikely. ...
Freshwater fishes are the second most threatened group of vertebrates after amphibians. In most developing countries, the conservation of freshwater fishes is largely hampered by limited information and data. The Red List assessments by the International Union for Conservation of Nature (IUCN) provide a benchmark for monitoring and mitigating species extinction risk, but these assessments require, inter alia, quantitative information on the species range in the wild. This information is largely missing for many species that face extinction threats. Here, we combine species occurrence data, expert knowledge, and literature to (i) review and update the distribution of non-Haplochromis fish species native to Uganda and (ii) determine the national geographical range of these fish species relative to their global range. For the latter, we use the IUCN’s standard protocol for mapping distribution of freshwater species from which we derive both the national and global extent of occurrence (EOO) and area of occupancy (AOO). We show that at least 110 non-Haplochromis species occur in Uganda, with the majority species having a wide distribution outside the national boundaries. However, substantial gaps exist in data on presence of the species in their native range, where more than 60% of the species are designated as “possibly extant.” We elaborate on fish species previously believed to occur in Uganda, e.g., Amphilius kivuensis Pellegrin, 1933; Bagrus degeni Boulenger, 1906; Marcusenius macrolepidotus (Peters, 1852); Petrocephalus catostoma (Günther, 1866); and Lacustricola pumilus (Boulenger, 1906), but where recent studies suggest they lack a native distribution within the country. In addition, we highlight fishes with occurrence records that site them in areas beyond their previously known range, requiring further investigations to ascertain their present status. This work has potential to (i) trigger evidence-driven policies aimed at site-based conservation and rethinking of extent of protected areas, (ii) stimulate data collection, especially in areas where fishes are designated as “possibly extant” and “presence uncertain,” and (iii) aid the IUCN Red List assessments, for which conservation status of the majority non-Haplochromis species is outdated and many others remain unevaluated due to lack of quantitative information on their range.
... Marcusenius victoriae and P. degeni occupy habitats with greatly differing environmental conditions within the Lake Victoria basin of East Africa, including Lake Victoria, Katonga River, and Lake Nabugabo (Chapman et al., 1996b ;Chapman and Chapman, 1998 ;Chapman and Hulen, 2001 ;Chapman et al., 2002 ;Clarke et al., 2020 ;Kramer et al., 2012 ;Moulton et al., 2020 ;Ogutu-Ohwayo, 1993). They belong to different subfamilies of the Mormyridae, Mormyrinae and Petrocephalinae, respectively, and differ in their electrosensory anatomy, overall morphology, and social behavior (Figure 2; Carlson, 2016). ...
In dieser Arbeit wurden die Morpho-Physiologie und das Verhalten zweier Arten Afrikanischer schwach elektrischer Fische, Marcusenius victoriae und Petrocephalus degeni, im Labor und in einem ihrer natürlichen Habitate im Lwamunda Sumpf in Uganda untersucht. Die zwei Hauptziele dieser Arbeit waren (i) tageszeitabhängige Verhaltensrhythmen (Aktivität, Habitatnutzung) im Labor und im Freiland zu untersuchen und (ii) die Ausprägung und Plastizität der morpho-physiologischen Merkmale von P. degeni zu untersuchen, die ihnen erlauben bei natürlich vorkommender, geringer Sauerstoffverfügbarkeit (Hypoxie) zu überleben. Tageszeitabhängige Verhaltensrhythmen beider Arten wurden im Labor über 42 Stunden und im natürlichen Habitat dieser Fische für sechs Tage erfasst. In den Laborversuchen verbrachten beide Arten tagsüber annähernd 100% der Zeit in einem bereitgestellten Versteck und schwammen nachts heraus um aktiv ihre Umwelt zu erkunden. Im Habitat wurden die meisten Fische in strukturell komplexen Habitaten unter schwimmenden Pflanzen detektiert. Nachts schwammen die Fische aktiv in die offenen und ungeschützten Bereiche der Lagune, vermutlich um nach Futter zu suchen und zu interagieren. Die Begleitende in-situ Messung der Sauerstoffverfügbarkeit zeigte, dass beide Arten präsent und vermutlich sogar am aktivsten waren während Phasen extremer nächtlicher Hypoxie. Zur Untersuchung der respiratorischen Merkmale von P. degeni wurden Respirometrieversuche mit hypoxie-akklimatisierten Tieren durchgeführt, Hämoglobin- und Laktatkonzentration im Blut gemessen, und morphologische Parameter an den ersten beiden Kiemenbögen erfasst. Die Fische zeigten niedrige Sauerstoffverbrauchsraten, welche sie bis zu einem sehr niedrigem äußeren Sauerstoffpartialdruck aufrechterhielten. Zusätzlich zeigten sie hohe Hämoglobin- und Laktatkonzentrationen im Blut. Bis zu 75 Tage Normoxie-Akklimatisierung führte zu reduzierter Hämoglobinkonzentration und kürzeren Kiemenfilamenten.
... It is listed by Greenwood (1966) to occur in Lake Victoria and Nabugabo and the Victoria Nile (East Coast Ichthyofaunal province), while other occurrence records from GBIF extend the distribution to Lakes Albert, Kyoga, George, Nabugabo, Kagera, and Nyaguo, which span two Ichthyofaunal provinces (Fig. 1). Such a distribution is not likely for lacustrine species, and therefore, the records in Uganda can be considered Petrocephalus degeni (Kramer et al., 2012). ...
Freshwater fishes are the second most threatened group of vertebrates after amphibians. In most developing countries, the conservation of freshwater fishes is largely hampered by limited information and data. The Red List assessments by the International Union for Conservation of Nature (IUCN) provide a benchmark for conservation and planning, but these assessments require, inter alia , quantitative information on the species range in the wild. This information is largely missing for many species that face extinction threats. In this paper, we combined species occurrence data, expert knowledge, and literature to review and update the distribution of non- Haplochromis fish species native to Uganda and determine their geographical extent relative to the global range. Results showed that (i) at least 110 non- Haplochromis species occur in Uganda, (ii) the current status in the entire native range for more than 60% of these species is unknown; (iii) five species previously known to occur in Uganda: Amphilius kivuensis, Bagrus degeni, Marcusenius macrolepidotus, Petrocephalus catostoma , and Lacustricola pumilus lack a native locus and hence not Ugandan fishes, (iv) 17 species occur in areas beyond their previously known range, and therefore, their presence needs further investigations, preferably by examining specimen collections, and (v) majority of the non- Haplochromis species native to Uganda have a wide distribution outside the national boundaries. We anticipate this information to be relevant both for the national and global IUCN Red List assessments for the non- Haplochromis fishes in Uganda. Furthermore, the identified data gaps will be relevant in prioritizing limited resources during surveys and collections.
... studies in the region have shown that most mormyrid genera contain a number of species that were previously unknown to science (Kramer, 2013;Kramer et al., 2003;Kramer et al., 2004;Kramer et al., 2007;Kramer et al., 2012;Kramer et al., 2016;Kramer & Swartz, 2010;Kramer & van der Bank, 2000;Kramer & van der Bank, 2011;Kramer & Wink, 2013;Maake et al., 2014). These studies have led to the description of 17 new species and the resurrection of 1 species, indicating that mormyrid diversity in southern Africa remains underestimated. ...
... Findings from the present study support a growing body of literature which shows that many of the species that were previously considered to have broad geographic ranges across multiple isolated river systems in southern Africa are complexes comprising several historically isolated lineages, with some of them representing novel species (Chakona et al., 2018;Eccles et al., 2011;Kramer et al., 2012;Maake et al., 2014;Riddin et al., 2016). There are at least seven lineages within the H. ansorgii complex that need to be formally described following generation of additional data and detailed examination of a comprehensive number of voucher specimens. ...
The present study used molecular and morphological approaches to investigate hidden diversity within the Hippopotamyrus ansorgii species complex in southern Africa. Phylogenetic reconstructions and three species delimitation methods based on two mitochondrial markers (cytochrome b and cytochrome oxidase I) and one nuclear marker (S7) revealed 12 Molecular Operational Taxonomic Units (MOTUs), with two of them representing two recently described species, Hippopotamyrus longilateralis and Hippopotamyrus szaboi. The highest diversity occurred in the Kwanza River system, which contained five MOTUs, and the Upper Zambezi River system that had two MOTUs. Five other river systems contained a single MOTU each. A major impediment to the review of this complex has been the uncertainty surrounding the type locality of the specimens that were used for the description of H. ansorgii. The present study has, through a careful examination of published literature and synthesis of information on the travel activities of Dr. William Ansorge who collected the specimens, identified the Kwanza River system as the most plausible source of the syntypes. The resolution of the type locality of H. ansorgii facilitates future work on the review of this complex which is critical for providing reliable biodiversity estimates, identifying effective conservation management strategies and understanding the evolutionary history and biogeographic patterns of the fishes of this region.
... OVA using data from 168 individuals pooled from 13 species. Given the morphological, physiological and behavioural differences between weakly electric fishes and other teleosts (Albert et al., 1997;Chapman et al., 2002;Chapman & Chapman, 1998;Chapman & Hulen, 2001;Sukhum et al., 2016), a common curve may not be appropriate (Lapointe et al., 2018). B. Kramer et al., 2012). Although consistent with previous studies of M. victoriae and other mormyrids, this extremely low critical oxygen tension in mormyrids is, nonetheless, remarkable given the previously estimated high metabolic cost of the EOD and T A B L E 2 Routine metabolic rates (RMR; adjusted to a common body mass of 17.10 g), routine electric organ ...
Environmental hypoxia has effected numerous and well‐documented anatomical, physiological and behavioural adaptations in fishes. Comparatively little is known about hypoxia's impacts on sensing because it is difficult to quantify sensory acquisition in vivo. Weakly electric fishes, however, rely heavily on an easily‐measurable sensory modality—active electric sensing—whereby individuals emit and detect electric organ discharges (EODs). In this study, hypoxia tolerance of a mormyrid weakly electric fish, Marcusenius victoriae, was assessed by examining both its metabolic and EOD rates using a critical threshold (pcrit) paradigm. The routine metabolic rate was 1.42 mg O2 h⁻¹, and the associated critical oxygen tension was 14.34 mmHg. Routine EOD rate was 5.68 Hz with an associated critical tension of 15.14 mmHg. These metabolic indicators of hypoxia tolerance measured in this study were consistent with those in previous studies on M. victoriae and other weakly electric fishes. Furthermore, our results suggest that some aerobic processes may be reduced in favour of maintaining the EOD rate under extreme hypoxia. These findings underscore the importance of the active electrosensory modality to these hypoxia‐tolerant fish.
... (Arnegard et al., , 2006(Arnegard et al., , 2010aArnegard & Hopkins, 2003;Gallant et al., 2011;Rich et al., 2017;Sullivan et al., 2002), Petrocephalus(Kramer et al., 2012;Lavoué et al., 2008Lavoué et al., , 2010Lavoué & Sullivan, 2014;Moritz et al., 2009), PollimyrusMarkowski et al., 2008) and Stomatorhinus Boulenger 1898.Carlson et al. (2011) and Carlson (2016) made a distinction between general patterns of EOD diversity in clade A mormyrids (this clade comprises most genera in the subfamily Mormyrinae, e.g. Paramormyrops, Marcusenius and Stomatorhinus) v. non-clade A taxa outside this clade (the subfamily Petrocephalinae, which comprises only Petrocephalus and the mormyrin genus Myomyrus). ...
Electroreception, the capacity to detect external underwater electric fields with specialised receptors, is a phylogenetically widespread sensory modality in fishes and amphibians. In passive electroreception, a capacity possessed by c. 16% of fish species, an animal uses low‐frequency‐tuned ampullary electroreceptors to detect microvolt‐range bioelectric fields from prey, without the need to generate its own electric field. In active electroreception (electrolocation), which occurs only in the teleost lineages Mormyroidea and Gymnotiformes, an animal senses its surroundings by generating a weak (< 1 V) electric‐organ discharge (EOD) and detecting distortions in the EOD‐associated field using high‐frequency‐tuned tuberous electroreceptors. Tuberous electroreceptors also detect the EODs of neighbouring fishes, facilitating electrocommunication. Several other groups of elasmobranchs and teleosts generate weak (< 10 V) or strong (> 50 V) EODs that facilitate communication or predation, but not electrolocation. Approximately 1.5% of fish species possess electric organs. This review has two aims. First, to synthesise our knowledge of the functional biology and phylogenetic distribution of electroreception and electrogenesis in fishes, with a focus on freshwater taxa and with emphasis on the proximate (morphological, physiological and genetic) bases of EOD and electroreceptor diversity. Second, to describe the diversity, biogeography, ecology and electric signal diversity of the mormyroids and gymnotiforms and to explore the ultimate (evolutionary) bases of signal and receptor diversity in their convergent electrogenic–electrosensory systems. Four sets of potential drivers or moderators of signal diversity are discussed. First, selective forces of an abiotic (environmental) nature for optimal electrolocation and communication performance of the EOD. Second, selective forces of a biotic nature targeting the communication function of the EOD, including sexual selection, reproductive interference from syntopic heterospecifics and selection from eavesdropping predators. Third, non‐adaptive drift and, finally, phylogenetic inertia, which may arise from stabilising selection for optimal signal‐receptor matching.
... Growing evidence from previous and ongoing DNA-based studies shows that many species of freshwater fishes that were previously considered to have wide geographic ranges are instead complexes comprising several genetically divergent lineages (e.g., Goodier et al. 2011;Kramer et al. 2004;Kramer and Wink 2013;Linder et al. 2010;Swartz et al. 2007Swartz et al. , 2009). These studies have stimulated renewed interest in the systematics of freshwater fishes in the region as evidenced by the recent revalidation of some junior synonyms as well as the identification and description of several new species (e.g., Chakona et al. 2014;Chakona and Skelton 2017;Kramer et al. 2003Kramer et al. , 2007Kramer et al. , 2012Kramer et al. , 2013Kramer et al. , 2014Kramer and Swartz 2010;Kramer and van der Bank 2011;Maake et al. 2014). There is thus need for expanding the application of molecular approaches as these may lead to the identification of presently unrecognised diversity and provide insights on the patterns of endemism of stream fishes from other understudied regions in southern Africa such as the EZH freshwater ecoregion. ...
Stream fishes of the Eastern Afromontane region are among the least studied vertebrates in this region, despite the potential for harbouring cryptic diversity. The present study examined mitochondrial cytochrome oxidase subunit I (COI) sequence divergence in 153 specimens of stream fishes belonging to four genera and three families, [( Amphilius and Zaireichthys (Amphiliidae); Chiloglanis (Mochokidae); and Hippopotamyrus (Mormyridae)], in the Eastern Zimbabwe Highlands (EZH) freshwater ecoregion to explore the extent to which the current taxonomy conceals the ichthyofaunal diversity in the region. The General Mixed Yule Coalescent (GMYC) species delineation method identified 14 clusters within five currently recognised ‘species’ from the EZH ecoregion. Only one of these clusters represents a named species, while 13 of them represent candidate or undescribed species. Our results revealed that effective conservation of this region’s unique biota is limited by the incomplete knowledge of taxonomic diversity and inaccurate mapping of species distribution ranges.
... with additions and modifications byKramer, Bills, Skelton, and Wink (2012) for measurements of the caudal peduncle depth, pectoral-pelvic distance, and snout length; caudal peduncle length was measuredfrom the ends of both dorsal and anal fins. Eleven meristic counts were taken in each specimen including numbers of rays in the dorsal, anal, pectoral and pelvic fins, numbers of scales in the lateral line and around the caudal peduncle, number of scale rows between the lateral line and origins of the dorsal and pelvic fins, numbers of teeth in upper and lower jaws, and total number of vertebrae. ...
Based on morphological data and analysis of mitochondrial cytochrome b gene and nuclear (S7 intron 1) DNA sequences, the phylogenetic relationships of all Pollimyrus species known from the Omo-Turkana enclosed basin and Nile system below the Murchison Falls were solved. A mormyrid “Pollimyrus” petherici is distantly related to all other studied Pollimyrus species and clusters together with Cyphomyrus species forming with the later a monophyletic group. Moreover, the West African (but not the Congo River) populations of Cyphomyrus psittacus, the type species of the genus, seem to be conspecific to C. petherici. That is, the range of the genus Cyphomyrus is extended toward the Nile and Omo-Turkana basins. This genus belongs to the large clade widely distributed in sub-Saharian Africa and characterized by the presence of a chin appendage. Significance of this character for mormyrid phylogeny is discussed. Two distinct lineages of Pollimyrus occurring sympatrically in the White Nile tributaries and previously reported as the light and dark forms of Pollimyrus isidori together with five other congeneric species studied form a monophyletic group. The light form apparently represents P. isidori distributed in the Nile system downstream of the Murchison Falls and West Africa; the dark-colored form (designated as Pollimyrus “D”) represents a distinct phylogenetic lineage inhabiting both the Omo-Turkana and the White Nile basin. Morphological and ecological data suggest that this form may be conspecific to East African Pollimyrus nigricans or most probably represents a new species.
