Influence of physicochemical parameters on the spatial distribution of snail species that are intermediate hosts of human schistosomes in the Senegal River Delta.

The objective of this work was to identify possible correlations between physicochemical parameters (water temperature, water flow velocity, electrical conductivity, dissolved oxygen, salinity, pH, nitrates, and phosphates) and the spatial distribution in the Senegal River delta of snail species that are intermediate hosts of human schistosomes. Eight water points (ME1 to ME4, NE1 and NE2, TA1 and TA2) were selected in the villages of Menguègne Boye, Ndellé Boye, and Thilla for biweekly monitoring of these snails and the physicochemical parameters of the water. The results show that the spatial distribution of the snail populations is related to pH, dissolved oxygen (mg/l), conductivity, temperature (̊C), and water flow velocity (m/s).

Role of environmental parameters on the density of intermediate host snails of human schistosoma during the year in the commune of Richard-Toll, Senegal.

The implementation and expansion of development projects (dams and irrigation schemes) in the Senegal River valley have led to a significant proliferation of snails. We conducted a one-year (2014) study project, monitoring their density in the commune of Richard Toll, to assess the role of environmental parameters on mollusc population dynamics. Four species involved in the transmission of human schistosomiasis were found: Bulinus globosus, B. truncatus, B. senegalensis, and Biomphalaria pfeifferi. Among the intermediate hosts, B. truncatus is the most abundant species, followed by B. globosus. Snail density depends on the nature of the water point but also on environmental parameters such as vegetation. This study showed that vegetation, water level (flood), and flow velocity influence the dynamics of the snail populations that are intermediate hosts of human schistosomes.

Savanna chimpanzee (Pan troglodytes verus) nesting ecology at Bagnomba (Kedougou, Senegal).

We studied the nesting behavior of the critically endangered West African chimpanzee (Pan troglodytes verus). We assumed that the nesting data stemmed from a single, unhabituated community at the Bagnomba hill site in the savanna-woodlands of southeastern Senegal. The aim of this study was to examine chimpanzees' nesting habits in terms of the tree species utilized and sleeping nest heights. We recorded a total of 550 chimpanzee nests at Bagnomba between January 2015 and December 2015. The chimpanzees here made nests in particular tree species more often than others. The majority of nests (63%) were in two tree species: Diospyros mespiliformis and Pterocarpus erinaceus. The average height of nesting trees was 10.54 m (SD 3.91, range, 0.0-29.0 m) and average nest height was 7.90 m (SD 3.62, range, 0.0-25.0 m). The result of a linear regression analysis (r = 0.7874; n = 550; p < 0.05) is consistent with a preference for nesting at a particular height. Bagnomba chimpanzees rarely made ground nests (0.36% of nests), but the presence of any ground nesting was unexpected, given that at least one leopard (Panthera pardus) also occupied the hill. This knowledge will enable stakeholders involved in the protection of chimpanzees specifically and of biodiversity in general to better understand chimpanzee ecology and inform a conservation action plan in Senegal where the survival of this species is threatened.

Ultrastructure of the spermatozoon of Helicometroides atlanticus (Digenea, Monorchiidae), an intestinal parasite of Parapristipoma octolineatum (Pisces, Teleostei) in Senegal.

The mature Helicometroides atlanticus spermatozoon exhibits an anterior electron-dense material, two axonemes of the 9+"1" pattern, a nucleus, two mitochondria, extramembranous ornamentations located at the level of the first mitochondrion and cortical microtubules arranged into two fields: a ventral field corresponding to the mitochondrial side and a dorsal field corresponding to the nuclear side. It lacks of spine-like body and a cytoplasmic expansion as in Monorchis parvus the only species of Monorchioidea which spermatozoon has been described until now. Nevertheless, it is distinguished from M. parvus by the presence of an anterior electron-dense material and two axonemes which appear one after the other.

Spermatological characteristics of Elstia stossichianum (Digenea, Mesometridae) from the intestine of the cow bream (Sarpa salpa) off Dakar, Senegal.

The current study was designed to increase the spermatological ultrastructural database on Digenea, thus contributing to the future establishment of phylogenetic relationships within this group based on ultrastructural characteristics of both spermiogenesis and spermatozoa. Spermiogenesis in Elstia stossichianum begins with the formation of a differentiation zone containing two centrioles, two striated rootlets, a nucleus, several mitochondria and an intercentriolar body constituted by seven electron-dense layers. Each centriole develops into a free flagellum growing orthogonally to the median cytoplasmic process. Proximo-distal fusion of the flagella with the median cytoplasmic process occurs after flagellar rotation. Both nucleus and mitochondria migrate before the complete proximo-distal fusion of both flagella with the median cytoplasmic process. Finally, the constriction of the ring of arched membranes gives rise to the young spermatozoon. The mature spermatozoon of E. stossichianum exhibits two axonemes of different length of the 9+'1' trepaxonematan pattern, a nucleus, a mitochondrion, two bundles of parallel cortical microtubules, external ornamentation of the plasma membrane, a lateral expansion, spine-like bodies, cytoplasmic ornamented buttons and granules of glycogen. The formation of cytoplasmic ornamented buttons during the final stages of spermiogenesis is reported here for the first time.

Ultrastructural study of the male gamete of Glossobothrium sp. (Cestoda: Bothriocephalidea: Triaenophoridae) a parasite of Schedophilus velaini (Perciformes: Centrolophidae) in Senegal.

This paper describes the ultrastructure of the male gamete of Glossobothrium sp. (Bothriocephalidea: Triaenophoridae). The mature spermatozoon of Glossobothrium sp. is filiform and possesses two axonemes, a single helicoidal crested body, a parallel nucleus, parallel cortical microtubules and granules of glycogen. In Glossobothrium sp. we describe for first time a 200-250 nm thick crest-like body in the Bothriocephalidean. The anterior part of the spermatozoon exhibits a ring of 27 electron-dense cortical microtubules encircling the first axoneme. This structure persists until the appearance of the second axoneme. When the ring of electron-dense cortical microtubules disappears, the spermatozoon exhibits two bundles of thin cortical microtubules. The posterior part of the spermatozoon contains the posterior extremity of the second axoneme, the posterior extremity of the nucleus and few cortical microtubules. Soon nucleus disappears and the axoneme is disorganized. Thus the posterior extremity of the spermatozoon of Glossobothrium sp. exhibits only singlets produced by the disorganization of the doublets of the second axoneme and few cortical microtubules. This type of posterior extremity of the mature spermatozoon has never been described previously in the Triaenophoridae.

Spermiogenesis and spermatozoon ultrastructure of Diplodiscus subclavatus (Pallas, 1760) (Paramphistomoidea, Diplodiscidae), an intestinal fluke of the pool frog Rana lessonae (Amphibia, Anura).

Spermiogenesis in Diplodiscus subclavatus begins with the formation of the zone of differentiation presenting two centrioles associated with striated roots and an intercentriolar body. The latter presents seven electron-dense layers with a fine central plate and three plates on both sides. The external pair of these electron-dense layers is formed by a granular row. Each centriole develops into a free flagellum, both of them growing orthogonally in relation to the median cytoplasmic process. After the flagellar rotation and before the proximodistal fusion of both flagella with the median cytoplasmic process four attachment zones were already observed in several cross-sections indicating the area of fusion. Spinelike bodies are also observed in the differentiation zone before the fusion of flagella. Finally, the constriction of the ring of arched membranes gives rise to the young spermatozoon that detaches from the residual cytoplasm. The mature spermatozoon of D. subclavatus shows all the classical characters observed in Digenea spermatozoa such as two axonemes of different length of the 9+"1" trepaxonematan pattern, nucleus, mitochondrion, two bundles of parallel cortical microtubules and granules of glycogen. However, some peculiarities such as a well-developed lateral expansion associated with external ornamentation of the plasma membrane and spinelike bodies combined with their area of appearance distinguish the ultrastructural organization of the sperm cells of D. subclavatus from those of other digeneans.

Variation in cestode assemblages of Mastomys and Arvicanthis species (rodents: Muridae) from Lake Retba in Western Senegal.

We studied patterns of variation in cestode communities of 3 abundant rodent species that live in sympatry in the Niayes of the Retba Lake, Western Senegal. We evaluated whether the host species have the same parasites and, within host species, whether the variability in parasite community is related to intrinsic (sex, age of the host individual) or extrinsic (habitat, season) factors. Arvicanthis niloticus was parasitized by 2 cestode species, namely Inermicapsifer madagascariensis and the highly dominant Raillietina trapezoïdes . Raillietina baeri was the only cestode species found in Mastomys erythroleucus , and there was no cestode in M. huberti . Prevalence and abundance levels of cestodes were very high in A. niloticus , especially in adults. Seasonal and habitat effects were found in both cestode communities of M. erythroleucus and A. niloticus . Local host specificity and abundance/prevalence levels suggested variations in the interaction between rodents and cestode intermediate host species among habitats and seasons.

[Carmyerius marchandi, a new species of trematode (Gastrothylacidae), a parasite of cattle in Senegal]. / Carmyerius marchandi, nouvelle espèce de trématode (Gastrothylacidae), parasite des bovins au Sénégal.

Carmyerius marchandi n. sp., a new species of trematode (Paramphistomoidea, Gastrothylacidae), has been described in Senegal. It has an average length of 13 +/- 1 mm and an average diameter of 3 +/- 0.4 mm. The brood pouch, bearing muscular invaginations and a ventrolateral swelling, makes up two thirds of the body length. There is a Carmyerius-type acetabulum. The ratio between the diameter of the acetabulum and body length is 1:7.4. The trematode has a Gastrothylax-type pharynx. The ratio between pharynx length and body length is 1:13.3. The ratio between pharynx length and acetabulum diameter is 1:1.8. The caeca extend beyond the mid section of the parasite. The lobed testicles are in a lateroposterior position. The ovary is situated between the two testicles and the uterus is in a mediodorsal position. The vitelline glands take up a large area in the ventrolateral swelling of the brood pouch. The small genital atrium is of the elongatus type. Using scanning electron microscopy, the parasite's body shows transverse ridging and tegumentary papillae around the oral aperture, genital pore and acetabulum. All of these characteristics indicate that this Gastrothylacidae belongs to the Carmyerius genus. To judge by the other species in the genus previously described, this appears to be a new species. We suggest that it should be named C. marchandi n. sp., as a token of gratitude to Professor Bernard Marchand.

Ultrastructure of spermiogenesis and the spermatozoon of Sudarikovina taterae (Cestoda, Cyclophyllidea, Anoplocephalidae) intestinal parasite of Tatera gambiana (Rodentia, Gerbillidae).

The young spermatid of Sudarikovina taterae exhibits a nucleus with a partially condensed chromatin and a differentiation zone, bordered by cortical microtubules, delimited at the front by arched membranes and containing two centrioles. The latter are parallel to one another and linked together at their bases by electron-dense material. During spermiogenesis, one of the centrioles gives rise to a flagellum whereas the other disappears. Crested-like bodies lie outside the cortical microtubules and the nucleus migrates in the spermatid along the axoneme. At the end of spermiogenesis, the ring of arched membranes constricts and the old spermatid becomes detached from the residual cytoplasm. The S. taterae mature spermatozoon is filiform and tapered at both extremities. It exhibits an apical cone of electron-dense material and seven crested-like bodies 50 to 100 nm thick. The cortical microtubules run along the whole length of the spermatozoon. They are spiralized at their anterior extremities and straight over the rest of their length. The nucleus is a fine compact cord interposed between the axoneme and the cortical microtubules. The cytoplasm is slightly electron-dense in regions I and II of the gamete. In regions III, IV and V, it contains fine electron-dense granulations and patches of electron-lucent material. An electron-dense material located both between and under centrioles has not been observed before in a platyhelminth. Similarly, distinctive ultrastructural characters between centrioles and seven crested-like bodies have not been previously described in a cestode. Moreover, we report for the first time the existence of cortical microtubules spiralized only at their anterior extremities in a cestode from a mammal.

Pterygodermatites (Mesopectines) senegalensis n. sp. (Nematoda, Rictulariidae), a parasite of Mastomys huberti (Rodentia, Muridae) in Senegal.

Pterygodermatites (Mesopectines) senegalensis n. sp. (Nematoda: Rictulariidae) is described from Mastomys huberti in Senegal. It differs from other species of the subgenus by the morphology of the head, which exhibits 4 simple cephalic papillae and a nearly axial buccal opening, the length of the spicules, the number of precloacal cuticular formations, and the absence of cephalic apophyses.

Ultrastructure of spermiogenesis and the spermatozoon of Vampirolepis microstoma (Cestoda, Hymenolepididae), intestinal parasite of Rattus rattus.

Spermiogenesis in Vampirolepis microstoma begins with the formation of a nuclear cone and a differentiation zone. This is delimited at the front by arched membranes, bordered by cortical microtubules, and contains two parallel centrioles linked together at their bases by electron-dense, amorphous material. The nuclear cone elongates, becomes filiform, and migrates into the spermatid body. Later, one of the centrioles gives rise to a flagellum that grows at the same pace as the cortical microtubules. Subsequently, 6 crested bodies form and the old spermatid separates from the residual cytoplasm. The mature V. microstoma spermatozoon is filiform and lacks mitochondria. Its anterior end exhibits six crested bodies 100 to 200 nm thick of unequal lengths. The axoneme is of the 9+"1" pattern. The cortical microtubules are spiralized and make an angle of about 20 to 30 degrees to the spermatozoon axis, except at their posterior extremity where they become parallel to this axis. The nucleus is an electron-dense cord coiled in a spiral around the axoneme. The cytoplasm is slightly dense but contains many electron-dense granules in regions III, IV, and V of the spermatozoon. The presence of centrioles linked together at their bases by electron-dense material has never, to our knowledge, been reported in a Platyhelminth. Likewise, a nuclear migration, right from the beginning to the end of spermiogenesis, has never been described in a cestode. In addition, we observe for the first time the existence of six crested bodies in a cestode from a Mammal.

Ultrastructure of spermiogenesis of Dipylidium caninum (Cestoda, Cyclophyllidea, Dipylidiidae), an intestinal parasite of Canis familiaris.

We describe for the first time the ultrastructure of spermiogenesis of a representative of the family Dipylidiidae, Dipylidium caninum. Spermiogenesis begins with the formation of a differentiation zone. This conical area presents two centrioles with associated striated roots. One of the centrioles develops a flagellum and posteriorly a proximodistal fusion is produced between the axoneme and a median cytoplasmic process. In a final stage of spermiogenesis a condensation of electron-dense material between cortical microtubules is observed in the anterior part of the differentiation zone. This is the origin of the crest-like body that appears at the end of spermiogenesis. The presence of striated roots associated with centrioles constitutes the first report of these structures in the spermiogenesis of a cyclophyllidean cestode.

Subulura saloumensis n. sp. (Nematoda, Subuluroidea) from four species of rodents in Senegal.

A new species of the genus Subulura is described from 4 new rodent hosts: Arvicanthis niloticus, Mastomys erythroleucus, Mastomys huberti, and Tatera gambiana. Subulura saloumensis n. sp. differs from the congeneric species by the morphology of its head. the absence of buccal lobes, the length of right and left spicules, the absence of caudal alae, and the existence of a caudal papillae with a sensorial bristle. The latter, which we observe for the first time in specimens gathered from M. huberti, has never previously been described in a species of the genus Subulura.

Gongylonema madeleinensis N. sp. (Nematoda:Spiruroidea), from Mastomys erythroleucus (Rodentia) from a Senegalese island.

A new species of gongylonematid parasites of the rodent Mastomys erythroleucus is described. Gongylonema madeleinensis n. sp. differs from the other species of the genus by the size of its eggs and spicules-gubernaculum complex, the form and distribution of its cuticular scutella, and the absence of a pore on its cephalic plate. After examination of the esophageal content of 270 continental and 29 insular rodents, G. madeleinensis n. sp. seems to be endemic to the island "des Madeleines" near Dakar, Senegal.

Ultrastructure of spermiogenesis and the spermatozoon of Nomimoscolex sp. (Cestoda, Proteocephalidea) intestinal parasite of Clarotes laticeps (Fish, Teleost) in Senegal.

Spermiogenesis in Nomimoscolex sp. begins with the formation of a differentiation zone delimited at the front by arched membranes. It is bordered by cortical microtubules and contains two centrioles surmounted each by striated roots. The latter are linked together at their bases by a thin layer of electron-dense material. The two centrioles give each a flagellum that rotates and fuses with the median cytoplasmic extension. The nucleus elongates, becomes filiform and migrates between the axonemes in the cytoplasmic extension. During the nuclear migration, crested-like bodies form. After the migration of the nucleus, the old spermatid separates from the residual cytoplasm by strangulation of the ring of arched membranes. The mature spermatozoon of Nomimoscolex sp. lacks mitochondria, is filiform and tapered at both its extremities. Its anterior end exhibits an apical cone of electron-dense material and three crested-like bodies of unequal length coiled in a spiral on its periphery. The axoneme is of the 9 + 1' pattern. The cortical microtubules are parallel to the spermatozoon axis. The nucleus is a fibrous cord of partly condensed chromatin. The cytoplasm is slightly dense but contains many electron-dense granules in regions II and III of the spermatozoon. Crested-like bodies and striated roots linked together by an electron-dense material have never been reported during the spermiogenesis in a proteocephalidean. In addition we describe for the first time the existence of three crested-like bodies in the Proteocephalidea.

Scanning electron microscope examination of scale-like spines on the rostellumm of five Davaineinae (Cestoda, Cyclophyllidea).

The study by scanning electron microscope of the scolex of Cotugnia polyacantha, Raillietina (R.) echinobothrida, R (R.) tetragona, R. (R.) tunetensis and R. (Skrjabinia) cesticillus allowed us to demonstrate the presence, on the rostellum of each individual, of scale-like spines. We believe that these scale-like spines represent a new character of diagnosis for the whole of the Davaineidae.

Ultrastructure of spermiogenesis and the spermatozoon of Aporina delafondi (Cyclophyllidea, Anoplocephalidae), intestinal parasite of turtle doves in Senegal.

Spermiogenesis in Aporina delafondi begins with the formation of a differentiation zone bordered by cortical microtubules and containing from the beginning a portion of nucleus and two parallel centrioles. One of the centrioles aborts, the other gives rise to a flagellum. The cortical microtubules elongate and spiralize while the nucleus migrates along the axoneme and crest-like bodies form at the level of the differentiation zone. The old spermatid separates from the residual cytoplasm by strangulation of the ring of arched membranes. The mature spermatozoon lacks mitochondria, is filiform and tapered at both its extremities. Its anterior extremity is capped by an apical cone of electron-dense material and exhibits five crest-like bodies of unequal lengths on its periphery. Its cortical microtubules are regularly spiralized except at their posterior extremity where they become parallel to the spermatozoon axis. The cytoplasm is slightly dense in the anterior regions (I and II) and exhibits many protein granules and patches of electron-lucent material in the middle (III) and posterior zones (IV and V). The nucleus is an electron-dense cord coiled in a spiral around the middle region (III) of the axoneme. This is of the 9+ "1" pattern and ends before the posterior extremity of the gamete. Spermiogenesis in Aporina delafonidi differs from that of the other Cyclophyllidea by the very early movement of the nucleus into the differentiation zone, the formation of a ring of arched membranes in the distal part of the differentiation zone, the appearance of crest-like bodies during migration of the nucleus and the formation of a cytoplasmic bud which contains the abortive centriole and develops to temporarily form a large lateral extension. The mature spermatozoon differs from that of the other Cyclophyllidea in the presence of lucent patches in its cytoplasm and of five helicoidal crest-like bodies. The systematic position of the genus Aporina is also debated.

Ultrastructure of spermiogenesis and the spermatozoon of Raillietina (Raillietina) tunetensis (Cyclophyllidea, Davaineidae), intestinal parasite of turtle doves in Senegal.

Spermiogenesis in Raillietina (Raillietina) tunetensis begins with the formation of a differentiation zone equipped with cortical microtubules and containing two centrioles. One of the centrioles very rapidly gives rise to a flagellum which fuses with a median cytoplasmic extension, the cortical microtubules elongate and arched membranes appear. After the migration of the nucleus two crest-like bodies form and the old spermatid becomes detached from the residual cytoplasm. The mature spermatozoon of R. (R.) tunetensis exhibits an apical cone of electron-dense material and two helicoidal crest-like bodies 100 to 200 nm thick. The cortical microtubules are spiralized and make an angle of about 60 degrees to the spermatozoon axis. The axoneme is of the 9 + "1" pattern and does not reach the posterior extremity of the gamete. The nucleus is a fine, compact cord wound in a spiral which may make as much as two complete coils round the axoneme. The cytoplasm is electron-dense in region V of the spermatozoon. Over the rest of the gamete it is made up of lucent material divided into irregular compartments by electron-dense material. The latter consists of a fine, discontinuous peri-axonemal sheath, a fine granular sub-microtubular layer situated in regions I and II, and irregularly spaced partitions localized in regions III and IV. A nucleus with an annular cross section has never been described in a cestode spermatozoon; nor have two crest-like bodies of different length and thickness. In addition we report for the first time the existence of crest-like bodies in the Davaineidae.

[Ultrastructural similarity of spermatozoa of some Cyclophyllidea]. / Similitude ultrastructurale des spermatozoïdes de quelques Cyclophyllidea.

The mature spermatozoa of Cotugnia polyacantha, Raillietina (R) tunetensis, Inermicapsifer madagascariensis and Avitellina centripunctata have an almost identical ultrastructural organization. They are tapered at both extremities. Their anterior extremity exhibits an apical cone of electron dense material and one or two helicoidal crested-like bodies. Their cortical microtubules are spiralized and are seen, in longitudinal and cross sections, as continuous, dense, submembranous material. Their nucleus is a cord of dense chromatin, coiled in a spiral around the 9 + "1" pattern axoneme. The cytoplasm is moderately dense to electron lucent and exhibits irregularly spaced walls of proteinaceous material and a fine periaxonemal sheath of dense material. In this work we show that the Anoplocephalidae are close to the Davaineidae by the characters of the spermatozoon and that Inermicapsifer should be put back among the Davaineidae, according to the opinion of Joyeux & Baer (1961) and come into conflict with other works more particularly Schmidt (1986).