A new genus and species of proteocephalidean (Cestoda) from Clarias catfishes (Siluriformes: Clariidae) in Africa

A new proteocephalidean cestode is described from 2 catfishes, Clarias gariepinus (type host) and C. cf. anguillaris (Siluriformes: Clariidae), from Ethiopia (type locality), Sudan, Tanzania, and Zimbabwe, and a new genus, Barsonella, is proposed to accommodate it. The genus belongs to the Proteocephalinae because its genital organs (testes, ovary, vitellarium, and uterus) are situated in the medulla. Barsonella lafoni, the type and only species of the new genus, is characterized mainly by the possession of an additional opening of each sucker; circular musculature on the anterior margin of suckers, serving as a sphincter; a small thin-walled glandular apical organ; absence of well-developed osmoregulatory canals in mature, pregravid, and gravid proglottids; and a large strobila, up to 173 mm long and 3.2 mm wide. Species of Marsypocephalus Wedl, 1861 (Marsypocephalinae), other large-sized proteocephalidean tapeworms occurring sympatrically in African catfishes (Clarias and Heterobranchus) and also possessing a sphincter-like, circular musculature on the anterior part of suckers, differ from B. lafoni in the absence of an additional sucker opening and glandular apical organ, the cortical position of the testes, well-developed osmoregulatory canals throughout the strobila, and a large cirrus sac. Proteocephalus glanduligerus (Janicki, 1928), another cestode parasitic in Clarias spp. in Africa, is much smaller than B. lafoni (maximum length 15 mm), has suckers without additional opening and circular musculature on the suckers, a large-sized glandular organ, much larger than suckers, and well-developed osmoregulatory canals. Comparison of partial sequences of the 28S rRNA gene for 7 samples of B. lafoni from 2 different hosts and 4 localities in Ethiopia, Sudan, and Tanzania has shown a very low genetic variability. In a limited phylogenetic analysis, B. lafoni formed a clade with Corallobothrium solidum Fritsch, 1886 (Proteocephalidae: Corallobothriinae), an African electric catfish parasite. This clade was the sister group of almost all Neotropical taxa from pimelodid and other catfishes.     

Redescriptions of the type specimens of six clarid species (Pisces) from Western Africa

Six species of genus Clarias (Clariidae) - Clarias angolensis Steindachner, Clarias liberiensis Steindachner, Clarias submarginatus Peters, Clarias laeviceps Gill, Clarias walkeri Günther and Clarias longior Boulenger — are redescribed from type specimens. It is shown that C. submarginatus and C. laeviceps should be properly ascribed to the subgenus Clarioides David and not to subgenus Allabenchelys (Boulenger), and that conversely C. walkeri belongs to subgenus Allabenchelys rather than subgenus Clarioides . It is further shown that C. longior has commonly been mistaken for C. laeviceps and that C. walkeri has often been mistaken for C. submarginatus . A general revision of the genus Clarias in Africa based on reference to type material is strongly recommended.     

The phylogenetic structure of habitat shift and morphological convergence in Asian Clarias (Teleostei, Siluriformes: Clariidae)

Catfishes of the genus Clarias are an important component of the ichthyofauna in Asia and in Africa. Previous studies demonstrated a high diversity in number of species, morphology and habitat, but little was known on the evolutionary processes underlying this diversity. We analysed an original data set of molecular sequences (cytochrome b and 16S genes), habitat and geographic distributions, as well as 29 morphometric measurements taken on 454 specimens of Asian Clarias . Maximum likelihood phylogeny estimation showed an unexpected cryptic diversity due to strong morphological convergence. The patterns of intra- and interspecific phylogenetic divergence are overall explained by geographic isolation. The analysis of habitat transitions with Markovian models showed that Asian Clarias evolved from an ancestor probably living in clear waters. The most frequent transitions occurred between clear and white waters, whereas transitions towards black waters occurred only from clear waters and were rare events. The morphometric analysis suggests a complex pattern of morphological evolution with repeated convergence towards an elongated form in black waters. The phylogeographic patterns of diversification of Asian Clarias agree with previous studies on other groups and the hypothesis that changes in sea level during the Pleistocene had little influence on shaping biodiversity on the Sunda Shelf.     

Isozyme variation among four species of the catfish genus Clarias

Native Thai species of Clarias catfishes and one species introduced from Africa can be easily distinguished by horizontal starch gel electrophoresis of allozymes. An undescribed species of Clarias was collected from Thailand and found to possess several fixed allelic differences from the Clarias previously studied.     

NEW DISTRIBUTION RECORDS FOR CLARIAS THEODORAE WEBER 1897, BARBUS EUTAENIA BOULENGER 1904, BARBUS POLYLEPIS BOULENGER 1907 AND OPSARIDIUM ZAMBEZENSE (PETERS 1852) FROM THE WATERBERG,TRANSVAAL, SOUTH AFRICA.

Summary

New distribution records for four fish species in the Waterberg mountains of the Transvaal were established during surveys since 1987–92. Clarias theodorae was previously reported from one locality each in the Waterberg and Soutpansberg. The current survey disclosed its presence at an additional 11 localities. In the Transvaal Opsaridium zambezense was previously only known from the eastern parts of the Province. The current survey revealed its presence at one locality in the Waterberg. Clarias theodorae and Opsaridium zambezense are regarded as threatened in South Africa. Barbus eutaenia (two populations in the Waterberg) and B. polylepis (one population in the Waterberg) have relatively wide distributions in the Transvaal but their presence in the Waterberg represent comparatively unique, isolated populations. All four species were only found in relatively small numbers. Droughts during the nineteen eighties, and a concurrent increase in farm weir construction and water abstraction, jeopardise the survival of these small fish populations. Extreme drought conditions during 1991/92 have exacerbated adverse conditions for fish survival even further due to a general cessation of stream flow.     

Genetically distinct Dutch-domesticated Clarias gariepinus used in aquaculture in southern Africa

Clarias gariepinus, a catfish species widely distributed in Africa including South Africa, is naturally absent from the Western Cape and the coastal Eastern Cape provinces. Because of its potential as an aquaculture species it has been widely used in aquaculture ventures in South Africa, specifically a stock known as Dutch catfish, a domesticated strain developed in the Netherlands. Mitochondrial DNA markers indicate that this stock is genetically distinct from the natural populations of C. gariepinus in South Africa. It could potentially pose a threat to South Africa's natural biodiversity if these fish were to escape from aquaculture farms, or was deliberately introduced into inland waters.     

Mitochondrial DNA variation of the common hippopotamus: evidence for a recent population expansion

Mitochondrial DNA control region sequence variation was obtained and the population history of the common hippopotamus was inferred from 109 individuals from 13 localities covering six populations in sub-Saharan Africa. In all, 100 haplotypes were defined, of which 98 were locality specific. A relatively low overall nucleotide diversity was observed (pi = 1.9%), as compared to other large mammals so far studied from the same region. Within populations, nucleotide diversity varied from 1.52% in Zambia to 1.92% in Queen Elizabeth and Masai Mara. Overall, low but significant genetic differentiation was observed in the total data set (F(ST) = 0.138; P = 0.001), and at the population level, patterns of differentiation support previously suggested hippopotamus subspecies designations (F(CT) = 0.103; P = 0.015). Evidence that the common hippopotamus recently expanded were revealed by: (i) lack of clear geographical structure among haplotypes, (ii) mismatch distributions of pairwise differences (r = 0.0053; P = 0.012) and site-frequency spectra, (iii) Fu's neutrality statistics (F(S) = -155.409; P < 0.00001) and (iv) Fu and Li's statistical tests (D* = -3.191; P < 0.01, F* = -2.668; P = 0.01). Mismatch distributions, site-frequency spectra and neutrality statistics performed at subspecies level also supported expansion of Hippopotamus amphibius across Africa. We interpret observed common hippopotamus population history in terms of Pleistocene drainage overflow and suggest recognising the three subspecies that were sampled in this study as separate management units in future conservation planning.     

Diet and feeding habits of the small catfish,Clarias liocephalus in wetlands of Western Uganda

Clarias liocephalus is an air‐breathing catfish inhabiting wetland and river systems in East Africa. This catfish is in high demand for sale as live bait in the Nile perch fishery of Lake Victoria and equally important in the diet of local communities in the lake basin. Wetland loss and increasing fishing pressure potentially threaten the persistence of C. liocephalus; however, little information exists on the ecology of this species to permit evaluation of current threats. This study quantified dietary characteristics of C. liocephalus from heavy and lightly fished wetlands in Western Uganda using numeric, gravimetric and volumetric indices on 492 stomach samples collected over one year. Clarias liocephalus was significantly smaller in three heavily fished sites, relative to the one in‐park site, likely a reflection of a size‐selective fishery. Across sites, C. liocephalus was a generalist feeder whose diet was dominated by aquatic dipteran larvae and plant material. The broad niche gives C. liocephalus an ecological advantage to forage effectively on a wide selection of prey. The significant presence of plant material shows that the species may utilize plant protein, an important consideration of diet requirements should the species be selected for aquaculture.     

A new species of the holothurian genus Pkyllophorus from South Africa with a key to subgenus Phyllophorella

Fourteen specimens of a shallow-water, sand-inhabiting, polytentaculate holothuroid, dredged from Durban, South Africa, are new and described as Phyllophorus (Phyllophorella) rosetta sp. nov. The new species is distinct in possessing an abundance of rosettes in all parts of the body wall, often in combination with tables typical of those of the Phyllophorus subgenus Phyllophorella Heding & Panning, 1954. In the form of its tables and rosettes the new species appears to be closely related to P. (P) contractura Cherbonnier, 1988 from Madagascar but differs from it in the form of its calcareous ring, the number of polian vesicles and the presence of rosettes throughout the body wall, instead of their restriction to the anal region. The presence of rosettes makes the new species, together with P. (P) contractura , a good intermediate between Phyllophorus and Lipotrapeza. The new species increases to nine the number of species now classified in the subgenus Phyllophorella. All nine species are keyed.     

Studies on Phytoremediation of Copper Using Pteridium Aquilinum (Bracken Fern) In the Presence of Biostimulants and Bioassay Using Clarias Gariepinus Juveniles

A study was carried out to evaluate the uptake of copper from water containing 10 mg/L copper by Pteridium aquilinum (bracken fern) and Clarias gariepinus in the presence of five plant growth stimulants: Nitrogen: phosphorus: potassium (15-15-15: an inorganic fertilizer), pig, cattle, poultry, and a mixture of pig/cattle manures. A plant growth stimulant differentiated each treatment. A 96-hour bioassay using C. gariepinus was carried out at the end of the experiment to test the efficacy of the clean up by P. aquilinum. The control experiment contained no copper or plant growth stimulant. Fish survival, uptake of copper by P. aquilinum, C. gariepinus, concentration of copper in water, hematology and histopathology of the fish were assessed. Higher concentrations of copper were reported in P. aquilinum than in water or C. gariepinus. Low fish mortality was reported with the highest being 20% in the cattle manure–containing treatment.     

Palatine torus in the pre-conquest inhabitants of the Canary Islands.

An unusually high frequency of palatine torus in prehistoric Canary Islands skeletal remains is investigated in terms of population origins, evolutionary forces (gene flow and genetic drift) and environmental effects. Palatine torus frequencies (percent presence) are compared between the Canary Islands sample and skeletal samples from proposed ancestral regions, including northwest Africa, northeast Africa, sub-Saharan Africa, southern Europe, northern Europe and western Asia. The frequency of palatine torus is much higher in the Canary Islands sample (23.8%) than in samples from Northern and sub-Saharan Africa (1.8-6.1%), southern Europe (7.5%) and western Asia (2.1%), but is much lower than in the sample from northern Europe (57.4%). Because biological and archaeological evidence provide strong support for a northwest African origin for indigenous Canary Islands populations, the relatively high occurrence of palatine torus in the Canary Islands populace cannot be explained by an alternative ancestry; rather, it may be best explained by either evolutionary forces such as genetic drift or gene flow, or by environmental forces, such as hard chewing or a heavy dependence on marine foods. Genetic drift and gene flow seem less likely, since frequencies of other dental traits known to be under strong genetic control do not differ greatly between the prehistoric Canary Islands and northwest African samples. Environmental factors such as diet seem the most likely explanation and may include heavy consumption of marine foods, which has been implicated in torus formation.     

Patterns of spatial genetic structuring in the endangered limpet Patella ferruginea: implications for the conservation of a Mediterranean endemic

Patella ferruginea Gmelin, 1791 is an endangered marine gastropod endemic to the Western Mediterranean. Its range is restricted to the Sardinian-Corsican region (SCR), North Africa, a few scattered sites in Southern Spain, and Sicily. Inter-simple sequence repeat (ISSR) markers and three different mitochondrial DNA (mtDNA) regions, Cytochrome c Oxidase subunit I, 12S (small-subunit ribosomal RNA gene) and 16S (large-subunit ribosomal RNA gene), were used to investigate the presence of genetic population structuring. The mtDNA sequences showed very low levels of genetic differentiation. Conversely, ISSRs showed the presence of two main genetic groups, corresponding to Spain, North Africa and Sicily and the SCR. The SCR was further split into two subgroups. The ISSR results suggest that, on a regional scale, the genetic structure of P. ferruginea is mainly determined by the restriction of gene flow by dispersal barriers. On a more local scale human harvesting may play a crucial role in population structuring by increasing the effect of genetic drift.     

Health assessment of freshwater fish species from Albasini Dam,outside a DDT-sprayed area in Limpopo province,South Africa: a preliminary study

During 2006 to 2008, the water, sediment and fish in Albasini Dam, used as a reference site outside a DDT-sprayed area, had been found to be as affected as those in the nearby DDT-sprayed area were. Accordingly, the aim of the current study, conducted in 2014, was to determine the health status of fish from Albasini Dam by means of a histology-based fish health assessment protocol. High levels of nitrates, as well as the organochlorine pesticides aldrin, dieldrin, chlordane and methoxychlor, were found in the water. Fish muscle tissue contained pesticides, including methoxychlor. A semi-quantitative histological assessment on Clarias gariepinus, Coptodon rendalli and Oreochromis mossambicus showed diverse histopathology in selected target organs, with the gills being most affected. Notably, the testis tissue of one C. rendalli was filled with eosinophilic liquid, characteristic of necrosis. Microscopic intersex was found in two of the nine O. mossambicus sampled. This is the second time that intersex as microscopic testicular oocytes has been reported in O. mossambicus in South Africa. This finding perhaps indicates that reproduction may be compromised and this will be investigated further. The presence of intersex and other histopathology in organs could be early warning signs of the declining water quality in this dam.     

Temporal patterning of electric organ discharges in the African electric catfish, Malapterurus electricus (Gmelin)

This paper is the first detailed analysis of situation-specific temporal patterning of electric organ discharges (EODs) in a strong electric fish. Using a resident-intruder paradigm EODs were recorded during interactions between dyads composed of Malapterurus electricus (Gmelin) and four different types of fish: (1) conspecifics; (2) large prey-type mid-water fish, goldfish ( Carassius auratus , Linnaeus 1758) and tilapia ( Oreochromis melanotheron , Rüppel, 1852); (3) a sympatric competitor, Polypterus palmas (Ayres 1850) and (4) a larger, threatening catfish, Clarias sp.
An analysis of the EODs emitted showed that in the presence of conspecifics the average EOD volley consisted of a single long-duration, low frequency train of EODs. The presence of the midwater fish (goldfish and Tilapia) elicited volleys consisting of two short trains, and P. palmas elicited long duration volleys with two trains and long inter-train intervals. Finally, an attacking Clarias resulted on average in volleys consisting of two high-frequency trains of EODs. With nonconspecific partner species resident electric catfish emitted volleys with more pulses, more trains that were longer in duration and higher in frequency than the EODs in volleys emitted by intruder electric catfish with the same species stimulus fish.     

The growth and feeding habits of Clarias anguillaris during their first season in the floodplain pools of the Sokoto-Rima river basin, Nigeria

The growth and feeding habits of juvenile Clarias anguillaris (Linné 1762) during their 5-month residence in the floodplain pools of the Sokoto-Rima river basin are described. A mean growth increment of 202 mm and 69.7 g attained in the October to March season compares favourably with first-year growth recorded for other Clarias species. The diet of C. anguillaris is relatively unspecialized and includes a wide variety of items ranging from algae, higher plant material and detritus through larval dipterans, rotifers and copepods, to fish. There is variation in the diet according to month of capture and capture location, and a reduction in diet diversity with fish size. The findings are discussed in the context of work carried out on other Clarias species. It is proposed that C. anguillaris is suitable for locally operated fish culture programmes.     

Crayfish,catfish and snails: the perils of uncontrolled biological control

A recent proposal that the Australian redclaw crayfish Cherax quadricarinatus and hybrid catfish could potentially control the snail hosts of schistosomiasis has been criticised on the grounds that crayfish pose a severe threat to aquatic ecosystems into which it might be introduced. This note examines the issue further, pointing out that both lack the host-specificity requirement to be a successful biological control agent. The catfish Clarias gariepinus is an omnivore and snails form only a small proportion of its diet; there is no evidence to suggest that it controls snail populations anywhere in Africa. The same applies to other species that have been proposed as biological control agents. Simple laboratory experiments are not an adequate guide to the efficiency of an animal as a biological control agent and detailed ecological investigations would usually demonstrate that few African fish species have this capability.     

Effect of Pinealectomy on Re-entrainment of Air-gulping Activity in Indian Walking Catfish,Clarias batrachus

The present study was aimed to examine the effect of pinealectomy on re-entrainment of air-gulping activity in Indian walking catfish Clarias batrachus under various LD phases. Live Clarias batrachus of mixed sex (40-50g body weight) were procured from the local market and kept in the stock aquaria under the laboratory conditions for proper acclimation. Following 7 days of acclimation, animals were randomly selected from the stock aquaria and divided into 2 groups. The pineal was surgically removed from one group (P_xG) and the other group was treated as intact control group (IG). Both groups were exposed under LD 12:12 cycle inside the chronocubicles. In every 7 days LD schedule was delayed by 4 hours by lengthening of the light-on time. Both intact and pinealectomized animals are exhibited 24h rhythm in air-gulping behaviour and its entrainability irrespective of phase shifts of LD cycle. However, the phase angle of peak with reference to light on hour gradually decreased from phase 1 to phase 4, irrespective of treatment (intact/pinealectomized). Further, it has been noticed that the occurrence of multifrequency rhythm (24h, 12h and 6h) is being decreased from phase 1 to phase 4. It could be concluded that daily light-dark cycle plays an important role in modulating the rhythmic characteristics of air-breathing activity in Clarias batrachus and that pinealectomy does not modulate the effects of LD cycles on such activity.     

Divergent haplotypes and human history as revealed in a worldwide survey of X-linked DNA sequence variation

The population genetic history of a 10.1-kbp noncoding region of the human X chromosome was studied using the males of the HGDP-CEPH Human Genome Diversity Panel (672 individuals from 52 populations). The geographic distribution of patterns of variation was roughly consistent with previous studies, with the major exception that 1 highly divergent haplotype (haplotype X, hX) was observed at low frequency in widely scattered non-African populations and not at all observed in sub-Saharan African populations. Microsatellite (short tandem repeat) variation within the sequenced region was low among copies of hX, even though the estimated time of ancestry of hX and other sequences was 1.44 Myr. The estimated age of the common ancestor of all hX copies was 5,230 years (95% consistency index: 2,000-75,480 years). To further address the presence of hX in Africa, additional samples from Chad and Tanzania were screened. Five additional copies of hX were observed, consistent with a history in which hX was present in Africa prior to the migration of modern humans out of Africa and with eastern Africa being the source of non-African modern human populations. Taken together, these features of hX-that it is much older than other haplotypes and uncommon and patchily distributed throughout Africa, Europe, and Asia-present a cautionary tale for interpretations of human history.     

Effect of administration of prostaglandin F2alpha or presence of an estrous teaser bitch on characteristics of the canine ejaculate

Semen was collected from eight dogs after SC administration of 0.1mg/kg PGF2alpha or 0.6 mL 0.9% NaCl solution 15 min prior to collection in the presence or absence of an estrous teaser bitch (switchback design; all dogs given all four treatments in random sequence). There were more spermatozoa (P=0.02) in ejaculates collected after administration of PGF2alpha in the presence of an estrous teaser bitch ((852+/-736)x10(6), mean+/-S.D.) than in ejaculates collected in saline-treated dogs in the absence of a teaser bitch ((371+/-620)x10(6)). However, the number of spermatozoa in the ejaculate of dogs given PGF2alpha in the absence of a teaser bitch and in dogs given saline in the presence of a teaser bitch ((556+/-494 and 600+/-622)x10(6), respectively) were not significantly different from each other or from the other two groups. The percentage of morphologically normal spermatozoa did not vary by treatment (P=0.51). In conclusion, treatment with PGF2alpha and presence of a teaser bitch had an additive effect on the number of spermatozoa. This, coupled with relatively minor side-effects, suggests this is a useful technique to increase number of spermatozoa in a single canine ejaculate.     

Male pheromone polymorphism and reproductive isolation in populations of Drosophila simulans

The dominant cuticular hydrocarbons (HC) in Drosophila simulans are 7‐tricosene (7‐T) and 7‐pentacosene (7‐P). The 7‐T is the major HC in East Africa and in other continents. In West Africa, D. simulans is very rare and displays 7‐P as the major compound. We studied three D. simulans strains from Egypt (Eg), Sao‐Tome (ST), and Cameroon (Cam), with 7‐T, intermediary or 7‐P phenotypes. HC profiles of ST and Cam female differed slightly from corresponding male profiles; females had more 7‐T and less 7‐P. Varying temperature affected all HCs (even those with 27 and 29 carbons)‐not just 7‐T and 7‐P; there was no clear relationship between HC phenotype and resistance to desiccation. We report reproductive isolation between Eg and ST and Eg and Cam (but not between ST and Cam), which is due to Eg and Cam female preferences for their own males. In conclusion, our findings do support divergence of D. simulans populations from West Africa for both pheromonal profile and mating preference.