A comparative study of the ultrastructural characteristics of the mature spermatozoa of two fellodistomids Tergestia clonacantha and T. laticollis and contribution to the phylogenetic knowledge of the Gymnophalloidea.

The ultrastructure of the mature spermatozoa of Tergestia clonacantha and T. laticollis collected from the digestive tracts of fishes from New Caledonia is described using transmission electron microscopy and compared to that of related species. The spermatozoa of the two species exhibit the general pattern described in most digeneans, namely two axonemes with the 9 + "1" pattern of the Trepaxonemata, nucleus, mitochondrion, cortical microtubules, an external ornamentation of the plasma membrane, spine-like bodies and granules of glycogen. The spermatozoa of T. clonacantha and T. laticollis show the same ultrastructural model with some specificities in each case, particularly in the disposition of the structures in the posterior extremities of the spermatozoon. This study confirms that ultrastructural characters of the mature spermatozoon are useful tools for the phylogenetic analysis of the Digenea.

TITLE: Étude comparative des caractéristiques ultrastructurales des spermatozoïdes mûrs de deux Fellodistomidae, Tergestia clonacantha et T. laticollis, et contribution à la connaissance phylogénétique des Gymnophalloidea. ABSTRACT: L'ultrastructure des spermatozoïdes mûrs de Tergestia clonacantha et T. laticollis, prélevés dans le tube digestif de poissons de Nouvelle-Calédonie, est décrite par microscopie électronique à transmission et comparée à celle d'espèces apparentées. Les spermatozoïdes des deux espèces présentent la structure générale décrite chez la plupart des digènes, à savoir deux axonèmes du type 9 + « 1 ¼ des Trepaxonemata, un noyau, une mitochondrie, des microtubules corticaux, des ornementations externes de la membrane plasmique, des corps épineux et des granules de glycogène. Les spermatozoïdes de T. clonacantha et T. laticollis présentent le même modèle ultrastructural avec quelques spécificités dans chaque cas, notamment dans la disposition des structures aux extrémités postérieures du spermatozoïde. Cette étude confirme que les caractères ultrastructuraux du spermatozoïde mûrs sont des outils utiles pour l'analyse phylogénétique des Digenea.

Spermatological characteristics of Sclerodistomoides pacificus (Digenea, Sclerodistomoididae) a parasite of the flying fish Cheilopogon pinnatibarbatus (Teleostei, Exocoetidae).

Sclerodistomoides pacificus is the only species described now in Sclerodistomoididae. We present in this paper the first ultrastructural data of the mature spermatozoon of a species from the genus Sclerodistomoides. Adult specimens of S. pacificus (Digenea: Hemiuroidea: Sclerodistomoididae), were parasites of the gall-bladder of the teleost fish Cheilopogon pinnatibarbatus captured in the Atlantic Ocean, near Dakar (Senegal). The male gamete is a filiform cell which exhibits a similar ultrastructural organization to that reported in most species belonging to the Hemiuroidea with two axonemes of the 9 + '1' pattern of trepaxonematans, a nucleus, a mitochondrion, external ornamentation of the plasma membrane not associated with cortical microtubules and located in the anterior region of the spermatozoon, and parallel cortical microtubules disposed in one side of the spermatozoon. However, the present study allowed describing for the first time a moniliform mitochondrion in the Hemiuroidea. The presence of a moniliform mitochondrion and the absence of filamentous external ornamentation described in other Hemiuridae: Lecithochirium microstomum, L. musculus and Hemiurus appendiculatus are a good tool for phylogenetic purposes in the Hemiuroidea. Moreover, spermatological organisation and model are discussed in context with those of previous studies in the Hemiuroidea.

Ultrastructure of mature spermatozoa of three Bucephalidae (Prosorhynchus longisaccatus, Rhipidocotyle khalili and Bucephalus margaritae) and phylogenetic implications.

We describe here the mature spermatozoa of three species of bucephalids, namely Bucephalus margaritae, Rhipidocotyle khalili and Prosorhynchus longisaccatus. This study provides the first ultrastructural data on the genera Bucephalus and Rhipidocotyle and enabled us to confirm the model of the mature spermatozoon in the Bucephalinae. The spermatozoon exhibits two axonemes with the 9 + "1" pattern of the Trepaxonemata, one of which is very short, lateral expansion, external ornamentation of the plasma membrane located in the anterior extremity of the spermatozoon and associated with cortical microtubules, spine-like bodies, a mitochondrion, and a nucleus. The maximum number of cortical microtubules is located in the anterior part of the spermatozoon. However, more studies are needed to elucidate if spine-like bodies are present in all the Bucephalinae or not. In the Prosorhynchinae, the mature spermatozoon exhibits a similar ultrastructural pattern. Some differences are observed, particularly the axoneme lengths and the arrangement of the spine-like bodies. The posterior extremity of the spermatozoon in the Bucephalinae exhibits only the nucleus, but prosorhynchines have microtubules.

Genetic and morphological characterization of Thysaniezia tapeworms from cattle and sheep in Senegal.

Genetic and morphological diversity of Thysaniezia tapeworms from cattle and sheep in Senegal was investigated using light and scanning microscopic observations and molecular analysis based on mitochondrial cytochrome c oxidase subunit 1 (cox1) and nuclear small subunit ribosomal RNA gene (SSU rDNA). A total of 52 adult tapeworms were collected from sheep and cattle. Although the tapeworms of the two hosts were morphologically very close, phylogenetic analysis based on cox1 and SSU rDNA gene sequences showed that they were divided into two clades corresponding each to a host. The maximum pairwise divergence between the clades were 12.1% in cox1 and 2.9% in SSU rDNA, indicating they are distinct species. The tapeworms collected from sheep were morphologically identified as Thysaniezia ovilla, a cosmopolitan species in domestic ruminants. Detailed morphological observations revealed a consistent difference between the tapeworms obtained from sheep and those from cattle. The latter were identified as Thysaniezia connochaeti. The present study highlights presence of two species of Thysaniezia among domestic ruminants in Senegal: T. ovilla specific to sheep and T. connochaeti specific to cattle. Our work is the first report of T. connochaeti from domestic animals.

Ultrastructural characteristics of the mature spermatozoon of the digenean Sclerodistomum italicum (Stossich, 1893) (Hemiuroidea, Sclerodistomidae) intestinal parasite of Hypocanthus amia (Teleostei, Carangidae).

The mature spermatozoon of Sclerodistomum italicum is filiform, tapered at both ends and shows the following features: 2 axonemes of the 9+"1" pattern of the Trepaxonemata, mitochondrion, nucleus and parallel cortical microtubules. The specific features of the spermatozoon of S. italicum include the simultaneous presence of two types of extramembranous ornamentations, the presence of short cortical microtubules in the anterior part of the spermatozoon and the presence of only one bundle of cortical microtubules in the median part of the spermatozoon. Thus far these structures are known only in the Hemiuroidea. The presence of filamentous ornamentation in the anterior extremity of the spermatozoon has not previously been described in the Sclerodistomidae. Similar to spermatozoa of other hemiuroideans, S. italicum lack spine-like bodies described in spermatozoa of many digenean taxa. The posterior extremity of the spermatozoon exhibits the same ultrastructural characteristics typical of the Hemiuroidea.

Prevalence and Scanning Electron Microscopic Identification of Anoplocephalid Cestodes among Small Ruminants in Senegal.

This study was undertaken to determine the prevalence of anoplocephalid cestodes in sheep and goats in Senegal. Intestines of 462 sheep and 48 goats were examined; 47.4% of sheep and 6.2% of goats were infected. The species identified and their prevalence were, among sheep, Avitellina centripunctata 38.7%, Moniezia expansa 15.4%, Stilesia globipunctata 16.7%, and Thysaniezia ovilla 0.4%. Among goats, they were M. expansa 6.2% and T. ovilla 2.1%. The prevalence of all species was not statistically different between dry and rainy seasons. The infections were single or multiple. Indeed, 56.2% of sheep were infected by a single species, 37.4% by two species, and 6.4% by three species. For goats, 66.7% were infected by M. expansa and 33.3% by both M. expansa and T. ovilla. Scanning electron microscopic (SEM) observations of tapeworms show the general diagnosis characters of these species.

The host specificity of ape malaria parasites can be broken in confined environments.

Recent studies have revealed a large diversity of Plasmodium spp. among African great apes. Some of these species are related to Plasmodium falciparum, the most virulent agent of human malaria (subgenus Laverania), and others to Plasmodium ovale, Plasmodium malariae and Plasmodium vivax (subgenus Plasmodium), three other human malaria agents. Laverania parasites exhibit strict host specificity in their natural environment. Plasmodium reichenowi, Plasmodium billcollinsi, Plasmodium billbrayi and Plasmodium gaboni infect only chimpanzees, while Plasmodium praefalciparum, Plasmodium blacklocki and Plasmodium adleri are restricted to gorillas and Plasmodium falciparum is pandemic in humans. This host specificity may be due to genetic and/or environmental factors. Infrastructures hosting captive primates, such as sanctuaries and health centres, usually concentrate different primate species, thus favouring pathogen exchanges. Using molecular tools, we analysed blood samples from captive non-human primates living in Gabon to evaluate the risk of Plasmodium spp. transfers between host species. We also included blood samples from workers taking care of primates to assess whether primate-human parasite transfers occurred. We detected four transfers of Plasmodium from gorillas towards chimpanzees, one from chimpanzees to gorillas, three from humans towards chimpanzees and one from humans to mandrills. No simian Plasmodium was found in the blood samples from humans working with primates. These findings demonstrate that the genetic barrier that determines the apparent host specificity of Laverania is not completely impermeable and that parasite exchanges between gorillas and chimpanzees are possible in confined environments.

[Living the aging in Senegal Perceptions/representations and coping strategies of persons of age three: results of investigations retrospective]. / Vivre le vieillissement au Sénégal Perceptions/représentations et stratégies d'adaptation des personnes du troisième âge : résultats d'enquêtes rétrospectives.

In Senegal, due to the young age of the population (60%) the concerns of the old tend to be put in the background. And yet, problems related to old age are a reality. These problems come up not in terms of demography (the old represent only 4.7% of the population), but in terms of the breaking-up of the social fabric, urbanization and the dismantling of the solidarity and poverty networks. This work is based on a collection of qualitative data from three studies conducted between 2008 and 2011 with the elderly to assess their real- life experiences, their perception of aging, their challenges and coping strategies. The results showed a transformation in the role and status of the old; this transformation being caused by social and society-related mutations. As a result, the inter-generation solidarity links have much loosened in the urban areas making the old people more vulnerable (in economic, social, health terms), especially those in charge of a family. The situation has been made worse by the unemployment affecting their offspring. In addition, the old people, who are often suffering from chronic diseases, find it hard to take charge of their medical expenses, despite the institution of the National Sesame Health Plan for the old or free health care policy. This has made them even more vulnerable. Yet before this precarious situation, the elderly develop strategies to cope with difficulties. Some recommendations have been made with a view to improving their lives and socioeconomic condition.

Ultrastructural study of the spermatozoon of Hemiurus appendiculatus (Digenea, Hemiuroidea, Hemiuridae), a parasite of Boops boops (Pisces, Teleostei, Sparidae) off Senegal.

The mature spermatozoon of Hemiurus appendiculatus exhibits the general pattern described in most of the digenean namely, two axonemes of the 9 + "1" pattern of the Trepaxonemata, a nucleus, a filiform mitochondrion, external ornamentations of the plasma membrane and parallel cortical microtubules located on one side of the spermatozoon. In this study, we show for the second time in a digenean spermatozoon the presence of microtubules of the second axoneme associated each in a short length with an external ornamentation, seven cortical microtubules, a terminal bulge in the anterior spermatozoon extremity separate from the remainder of the spermatozoon by a transverse constriction and the simultaneous presence of the external ornamentation of the plasma membrane with a filamentous ornamentation. The external ornamentations have a differentiated distribution, cover almost the anterior region of the spermatozoon, are more abundant around the first axoneme and extend backwards over a short distance around the second axoneme. This study also allowed us to reveal for the first time the existence in the Hemiuroidea of an axoneme that begins to disrupt before reaching the front end of the mitochondrion.

Haemosporidian Parasites of Antelopes and Other Vertebrates from Gabon, Central Africa.

Re-examination, using molecular tools, of the diversity of haemosporidian parasites (among which the agents of human malaria are the best known) has generally led to rearrangements of traditional classifications. In this study, we explored the diversity of haemosporidian parasites infecting vertebrate species (particularly mammals, birds and reptiles) living in the forests of Gabon (Central Africa), by analyzing a collection of 492 bushmeat samples. We found that samples from five mammalian species (four duiker and one pangolin species), one bird and one turtle species were infected by haemosporidian parasites. In duikers (from which most of the infected specimens were obtained), we demonstrated the existence of at least two distinct parasite lineages related to Polychromophilus species (i.e., bat haemosporidian parasites) and to sauropsid Plasmodium (from birds and lizards). Molecular screening of sylvatic mosquitoes captured during a longitudinal survey revealed the presence of these haemosporidian parasite lineages also in several Anopheles species, suggesting a potential role in their transmission. Our results show that, differently from what was previously thought, several independent clades of haemosporidian parasites (family Plasmodiidae) infect mammals and are transmitted by anopheline mosquitoes.

Study of the snail intermediate hosts of urogenital schistosomiasis in Niakhar, region of Fatick, West central Senegal.

BACKGROUND: Schistosoma haematobium is the most widespread schistosome species in Senegal and occurs in several regions of the country especially in the Sudan-Sahelian zone. The aims of the study were i) to determine the freshwater species ii) to ascertain the role of the identified snail species in the transmission of S. haematobium and iii) to study the impact of drought on the snails. METHODS: Snails were sampled each year in 17 sites from July to November-December 2012 and 2013. At each snail survey, snails were grouped by village, counted, identified according to shell morphology and the rates of schistosome cercarial shedding recorded. The shell height of the snails collected in July was measured and classified into four groups according to their size in order to determine those that are open to aestivation. RESULTS: B. senegalensis and B. umbilicatus were the only snails intermediate hosts collected in the Niakhar study area. B. senegalensis is found in all the 17 sampling sites while B. umbilicatus was only found in one site out of the many surveyed. The total number of B. senegalensis collected in 2012 and 2013 was 1032 and 8261 respectively. A total of 901 and 6432 B. senegalensis were tested for Schistosoma spp. infestation in 2012 and 2013 respectively. For B. umbilicatus, 58 snails were collected and tested in 2012. In 2013, 290 were collected and 281 tested. The overall rates of schistosome cercarial shedding were 0% in 2012 and 0.12% in 2013 for B. senegalensis and 13.79 and 4.98% in 2012 and 2013 respectively for B. umbilicatus. For both species collected in July, size group 3 individuals (7-9.9 mm) were the most numerous, 63.6 and 57.8% for B. senegalensis and B. umbilicatus respectively. B. umbilicatus was reported for the first time in the region of Fatick located in the old ecological zone of Sine-Saloum, is able to maintain Schistosoma spp. larvae during 7 months of drought and may transmit the disease in early July, increasing the period and the risk of transmission. CONCLUSION: This study recommends an adaptation of snail control strategies at pond cycles and ecology of the snails in these seasonal foci. Malacological control strategies must take into account these phenomena of drought resistance and the capacity of some snails to maintain parasite during aestivation. The treatment of ponds with Bayluscide at the end of the rainy season in November and upon onset of rains in July would be more advantageous to the control of snails thereby reducing transmission of urogenital schistosomiasis in the Niakhar area.

Ultrastructural characters of the spermatozoa in Digeneans of the genus Bianium Stunkard, 1930 (Digenea, Lepocreadiidae) parasites of fishes: a comparative study of Bianium plicitum and Bianium arabicum.

We present in this paper the first ultrastructural study of the spermatozoon of species of the genus Bianium Stunkard, 1930, namely Bianium plicitum and Bianium arabicum belonging to the family Lepocreadiidae. Specimens are parasites of the tetraodontid teleosts Lagocephalus laevigatus caught in the Atlantic Ocean and Lagocephalus sceleratus caught in Pacific Ocean, respectively. Live worms were fixed and processed for transmission electron microscopy. Observations of numerous cross and longitudinal sections of the spermatozoa of B. plicitum and B. arabicum demonstrated the general pattern described in all previously studied Lepocreadioidea, namely two axonemes with 9+ "1" pattern of Trepaxonemata, two mitochondria, a nucleus, parallel cortical microtubules, and an external ornamentation of the plasma membrane associated with spine-like bodies. The maximum number of cortical microtubules and the external ornamentation were not located at the anterior extremity of the spermatozoon but at a more posterior level, as in all the species of Lepocreadioidea studied to date. Differences observed between spermatozoa of B. plicitum and B. arabicum were observed in: (1) the location of the first mitochondrion, (2) size of cortical microtubules which were longer in B. arabicum than in B. plicitum, and (3) the order of the disappearance of the axonemes, mitochondrion, and cortical microtubules toward the posterior region of the spermatozoon. Only the nucleus reaches into the posterior extremity of the spermatozoon in these two species. The general pattern of the spermatozoon described in these two species exhibit the general model in the genus Bianium.

Efficacy of praziquantel against urinary schistosomiasis and reinfection in Senegalese school children where there is a single well-defined transmission period.

BACKGROUND: Human schistosomiasis is a significant health problem in Sub-Saharan Africa. In Niakhar, West central Senegal, the transmission of S. haematobium occurs seasonally between July and November. No control measures have been implemented despite high prevalence reported in previous studies. This aim of this study was to i) determine the current prevalence of S. haematobium in children at Niakhar, ii) assess the efficacy of one dose of PZQ (40 mg/kg) against S. haematobium and iii) monitor reinfection. METHODS: The current study was carried out in a cohort of 329 children aged five to 15 years enrolled from six villages in Niakhar to determine the efficacy of one dose of PZQ, as well as reinfection. Parasitological screening was performed in June 2011 to determine the baseline prevalence of S. haematobium, and then a single dose of PZQ was administered to all selected subjects in the transmission season in August 2011. The efficacy of PZQ treatment and reinfection were monitored respectively five weeks after in September 2011 and from February to March 2012. RESULTS: At baseline, the overall prevalence and the heavy intensity of infection were 73.2% and 356.1 eggs/10 ml of urine. Significant differences in the prevalence and intensity of S. haematobium infection were noted between villages. A single dose of PZQ significantly reduced the prevalence of S. haematobium infection from 73.2% to 4.6% and the geometric mean intensity of infection from 356.1 to 43.3 eggs/10 ml of urine. The cure rates ranged from 89.4% to 100%. The egg reduction rates also ranged from 77.6% to 100%. Two to three months after the period of transmission, the overall rate of reinfection was 12.6% and was significantly higher in male children than in female children. The overall prevalence at this period was 13.8%, which was significantly lower than the prevalence at baseline (73.2%). CONCLUSION: The Niakhar study area remains a hot spot of urinary schistosomiasis in Senegal with differences in transmission between villages. This study suggests that when transmission is strictly seasonal, Praziquantel shows the expected efficacy in reducing the prevalence and intensity of infection, but also a significant effect on the occurrence of reinfection.

Malaria-like symptoms associated with a natural Plasmodium reichenowi infection in a chimpanzee.

Although Plasmodium infections have never been clearly associated with symptoms in non-human primates, the question of the pathogenicity of Plasmodium parasites in non-human primates still remains unanswered. A young chimpanzee, followed before and after release to a sanctuary, in a semi-free ranging enclosure located in an equatorial forest, showed fever and strong anaemia associated with a high Plasmodium reichenowi infection, shortly after release. The animal recovered from anaemia after several months despite recurrent infection with other Plasmodium species. This may be the first description of malaria-like symptoms in a chimpanzee infected with Plasmodium.

Diversity of malaria parasites in great apes in Gabon.

BACKGROUND: Until 2009, the Laverania subgenus counted only two representatives: Plasmodium falciparum and Plasmodium reichenowi. The recent development of non-invasive methods allowed re-exploration of plasmodial diversity in African apes. Although a large number of great ape populations have now been studied regarding Plasmodium infections in Africa, there are still vast areas of their distribution that remained unexplored. Gabon constitutes an important part of the range of western central African great ape subspecies (Pan troglodytes troglodytes and Gorilla gorilla gorilla), but has not been studied so far. In the present study, the diversity of Plasmodium species circulating in great apes in Gabon was analysed. METHODS: The analysis of 1,261 faecal samples from 791 chimpanzees and 470 gorillas collected from 24 sites all over Gabon was performed. Plasmodium infections were characterized by amplification and sequencing of a portion of the Plasmodium cytochrome b gene. RESULTS: The analysis of the 1,261 samples revealed that at least six Plasmodium species circulate in great apes in Gabon (Plasmodium praefalciparum, Plasmodium gorA (syn Plasmodium adleri), Plasmodium gorB (syn Plasmodium blacklocki) in gorillas and Plasmodium gaboni, P. reichenowi and Plasmodium billcollinsi in chimpanzees). No new phylogenetic lineages were discovered. The average infection rate was 21.3% for gorillas and 15.4% for chimpanzees. A logistic regression showed that the probability of infection was significantly dependent on the freshness of the droppings but not of the host species or of the average pluviometry of the months of collection.

Genetic characterization of Moniezia species in Senegal and Ethiopia.

Genetic diversity of Moniezia spp. from domestic ruminants in Senegal and Ethiopia was investigated based on the nucleotide sequences of mitochondrial cytochrome c oxidase subunit 1 (cox1) and nuclear small subunit ribosomal RNA gene (SSU rDNA). A total of 64 adult tapeworms were collected from sheep, goat and cattle, and the tapeworms from cattle were all morphologically identified as Moniezia benedeni. On the other hand, the tapeworms obtained from sheep and goat were identified as Moniezia expansa or could not be identified because of the lack of diagnostic morphologic character, i.e. interproglottidal glands (IPGs). Phylogenetic analysis based on cox1 gene sequences revealed that the worms from sheep/goat and cattle formed distinct clades, and three mitochondrial lineages were confirmed within the sheep/goat tapeworms. The maximum pairwise divergences among the three mitochondrial linages were about 3% in cox1 and 0.1% in SSU rDNA, while that between the worms from sheep/goat and cattle reached 13% in cox1 and 2.7% in SSU rDNA. All of the three mitochondrial lineages contained tapeworms morphologically identified as M. expansa, and the tapeworms without IPGs were confirmed in one of the three lineages, indicating the tapeworms without IPGs were also M. expansa.

Collyricloides massanae (Digenea, Collyriclidae): spermatozoon ultrastructure and phylogenetic importance.

The spermatological characteristics of Collyricloides massanae (Digenea: Collyriclidae), a parasite of Apodemus sylvaticus caught in France, were studied by means of transmission electron microscopy. The mature sperm of C. massanae presents two axonemes of different lengths with the 9 + "1" pattern of the Trepaxonemata, two bundles of parallel cortical microtubules, external ornamentation of the plasma membrane, spine-like bodies, one mitochondrion, a nucleus and granules of glycogen. An analysis of spermatological organisation emphasised some differences between the mature spermatozoon of C. massanae and those reported in the Gorgoderoidea species studied to date, specially belonging to the families Dicrocoeliidae, Paragonimidae and Troglotrematidae. The ultrastructural criteria described in C. massanae such as the morphology of both anterior and posterior spermatozoon extremities, the association "external ornamentation+cortical microtubules", the type 2 of external ornamentation and the spine-like bodies would allow us to bring closer the Collyriclidae to Microphalloidea. However, further ultrastructural and molecular studies are needed particularly in the unexplored taxa in order to fully resolve the phylogenetic position of the Collyriclidae.

Ultrastructural characters of the spermatozoa in Digeneans of the genus Lecithochirium Lühe, 1901 (Digenea, Hemiuridae), parasites of fishes: comparative study of L. microstomum and L. musculus.

This study provides the first ultrastructural data of spermatozoa in the genus Lecithochirium. The spermatozoa of L. microstomum (from Trichiurus lepturus in Senegal) and L. musculus (from Anguilla anguilla in Corsica) exhibit the general pattern described in the great majority of the Digenea, namely two axonemes with the 9 + "1" pattern typical of the Trepaxonemata, one mitochondrion, a nucleus, parallel cortical microtubules and external ornamentation of the plasma membrane. Spermatozoa of L. microstomum and L. musculus have some specific features such as the presence of a reduced number of cortical microtubules arranged on only one side of the spermatozoon, the lack of spine-like bodies and expansion of the plasma membrane. The external ornamentation of the plasma membrane entirely covers the anterior extremity of the spermatozoa. The ultrastructure of the posterior extremity of the spermatozoa corresponds to the pattern previously described in the Hemiuridae, characterized by only singlets of the second axoneme. A particularity of these spermatozoa is the organization of the microtubule doublets of the second axoneme around the nucleus in the posterior part of the spermatozoon.

Pterygodermatites (Mesopectines) quentini (Nematoda, Rictulariidae), a parasite of Praomys rostratus (Rodentia, Muridae) in Mali: scanning electron and light microscopy.

Pterygodermatites (Mesopectines) quentini n. sp. (Nematoda, Rictulariidae) is described from the murine host Praomys rostratus in the south of the Republic of Mali. It differs from other species of the subgenus by the morphology of the head, which bears four simple cephalic papillae and a nearly axial oral opening, the number of caudal papillae, the number of precloacal cuticular formations, unequal spicules and the ratio of spicule lengths/body length. The use of scanning electron microscopy in combination with conventional light microscopy enabled us to give a detailed description of the morphological characters of this new species.

A new species of Spirura Blanchard, 1849 (Nematoda: Spiruridae) parasite of Heliosciurus gambianus and Xerus erythropus (Rodentia: Sciuridae) in Senegal.

A new species of Spirura is described from the stomach of Heliosciurus gambianus and Xerus erythropus (Sciuridae). Considering the number of preanal papillae of males, Babero (1973 ) and Giannetto and Canestri Trotti (1995) proposed the subdivision of the genus into 2 groups; those with 4 pairs of preanal papillae (25 species) and with more than 4 pairs of preanal papillae (4 species). Spirura mounporti n. sp. belongs to the second, with 5 pairs of preanal papillae, and differs from Spirura infundibuliformis (McLeod, 1933) Anderson et al., 1993 , Spirura zapi ( Erickson, 1938 ) Chabaud et al., 1965 , Spirura leiperi Gupta and Trivedi, 1985, and Spirura michiganensis Sandground, 1935 in the number of pairs of pre-cloacal papillae. The new species further differs from other species of the genus in having 21 caudal papillae, in the ratio of spicules:body length, and in its morpho-anatomical characters.