Iva Přikrylová

Parasite hybridization in African Macrogyrodactylus spp. (Monogenea, Platyhelminthes) signals historical host distribution

Macrogyrodactylus spp. from the gills of Clarias gariepinus in Zimbabwe and Kenya, and C. anguillaris in Senegal were identified using haptoral sclerite morphology and by sequencing the nuclear ribosomal DNA internal transcribed spacers (ITS) 1 and 2, partial 18S and the complete 5.8S rRNA gene. A molecular phylogeny was constructed using all sequenced Macrogyrodactylus species to date. Based on morphology, Macrogyrodactylus congolensis, M. heterobranchii, M. clarii, and M. karibae were identified, with one specimen from Zimbabwe displaying morphological features that were intermediate between M. heterobranchii and M. clarii. In the intermediate form, the partial 18S and ITS1 sequence was identical to that of M. clarii while the remaining ITS1 and complete ITS2 region was almost identical to M. heterobranchii as was the partial cox1 fragment, thus strongly suggesting a hybrid origin. At present, the catfish host of M. heterobranchii and M. clarii do not co-occur in southern Zimbabwe; this hybridization event is therefore proof of historical sympatry of both fish species.

Gyrodactylus species (Monogenea: Gyrodactylidae) on the cichlid fishes of Senegal, with the description of Gyrodactylus ergensi n. sp. from Mango tilapia, Sarotherodon galilaeus L. (Teleostei: Cichilidae)

The first record of Gyrodactylus species Nordmann, 1832 on the cichlid fish from Senegal is reported. Gyrodactylus parasites were found on four host species studied, Hemichromis fasciatus, Hemichromis letournaeuxi, Oreochromis niloticus, and Sarotherodon galilaeus. Gyrodactylus cichlidarum Paperna (Bamidgeh 13:14–29, 1968) were collected from H. fasciatus, and its identity was confirmed based on the morphometrical comparison with the holotype specimens of G. cichlidarum. Only one specimen of Gyrodactylus sp. was noted on H. letournaeuxi. The gyrodactylid specimens on O. niloticus and S. galilaeus were described as Gyrodactylus ergensi n. sp. based on the detailed morphometrical analysis supported by sequencing. The haptoral sclerites of G. ergensi n. sp., which closely resemble those of Gyrodactylus nyanzae Paperna, 1973, are compared with the type material and discussed. A partial sequence of the internal transcribed spacer recombinant DNA (ITS rDNA) was obtained from two specimens of G. ergensi, and a close relationship between G. ergensi n. sp. and G. cichlidarum is suggested based on 92% similarity in ITS rDNA region.

A new gyrodactylid (Monogenea) genus on gray bichir, Polypterus senegalus (Polypteridae) from Senegal (West Africa).

Abstract Diplogyrodactylus martini n. g. et sp., a viviparous monogenean, is described from the gills of gray bichir Polypterus senegalus Cuvier, 1829, in Senegal. This new genus can be readily distinguished from the other described viviparous genera based on the morphology of the attachment apparatus. The haptor is equipped with a pair of centrally positioned hamuli, a simple ventral bar without membrane and 8 pairs of marginal hooks of 2 types, 5 pairs of hooks with well-defined large falculate sickles, and 3 pairs of smaller hooks with well-articulated sickles. The new genus is unique in having a teardrop-shaped muscular tubular male copulatory organ which lacks spines. A partial sequence of the internal transcribed spacer (ITS rDNA) was obtained from 4 specimens of D. martini. The relationship among D. martini and other genera of the Gyrodactylidae is discussed based on the similarities of the attachment apparatus.

An overview of the Gyrodactylus (Monogenea: Gyrodactylidae) species parasitizing African catfishes, and their morphological and molecular diversity.

An overview of Gyrodactylus infecting catfishes from the African continent is provided, including new data from Sudan, Senegal, Kenya and Mozambique. Haptoral sclerite morphometry and nuclear ribosomal DNA sequences revealed the presence of eight Gyrodactylus species. On Senegalese Synodontis nigrita, Gyrodactylus synodonti n. sp. and Gyrodactylus nigritae n. sp. are described. These are the first reports of gyrodactylid parasites from mochokid hosts. From the fins of North African catfish Clarias gariepinus collected in Mozambique, Gyrodactylus alekosi n. sp. and Gyrodactylus rysavyi were identified. G. rysavyi was also reported from Kenyan C. gariepinus and Senegalese Clarias anguillaris. From the fins of C. anguillaris studied in Senegal, two more species, Gyrodactylus transvaalensis and Gyrodactylus gelnari n. sp. were recognised. In addition, Gyrodactylus turkanaensis n. sp. from the gills of Kenyan C. gariepinus was described and an undescribed Gyrodactylus sp. was recorded from Sudanese representatives of the same host. Detailed morphometrical and molecular comparisons of the species are presented and discussed. The study highlights the hitherto understudied diversity of viviparous monogenean parasites throughout Africa.

Monogenean parasites of introduced pumpkinseed Lepomis gibbosus(Centrarchidae) in the Danube River Basin

The pumpkinseed, Lepomis gibbosus, a centrarchid fish native to eastern North America, was introduced into Europe at the end of the 19th century. Lepomis gibbosus now represents one of the most successful of introduced fish species, having spread widely throughout many European countries. In this study, we collected monogenean parasites of L. gibbosus from four sites in the Danube River Basin. We recorded four monogenean species: Gyrodactylus sp., probably acquired in the area of introduction, and Onchocleidus similis, O. dispar and Actinocleidus recurvatus, species introduced together with their host. Onchocleidus similis dominated the parasite community at all sampling sites. Actinocleidus recurvatus has only been reported from southern Europe to date and, therefore, this is the first report of A. recurvatus from Central Europe and the Danube River Basin. We observed high morphological variability in both anchor pairs of A. recurvatus. Only in O. similis was there a positive correlation observed between haptor metric traits and fish host length. Differences in metric traits between native and introduced O. similis populations may reflect a difference in fish host size, the introduced fish host achieving a smaller size than fish from native populations. A detailed analysis of microhabitat distribution indicated a preference for the second gill arch for both dominant species O. similis and A. recurvatus, with dissimilar site segregation.

Morphometric comparison of three members of the Gyrodactylus nemachili-like species group (Monogenea: Gyrodactylidae) on Barbatula barbatula L. in the Czech Republic, with a reinstatement of G. papernai Ergens & Bychowsky, 1967

The Gyrodactylus nemachili-like species complex, parasitising stone loach Barbatula barbatula L. in the Czech Republic, was investigated based on the detailed morphometric analysis of its haptoral hard parts. The existence of two species, G. jiroveci Ergens & Bychowsky, 1967 and G. pseudonemachili Ergens & Bychowsky, 1967 was confirmed. A standard discriminant analysis of the morphometric data showed a clear separation between specimens of G. jiroveci and another species or variant. Based on the morphology of the haptoral hard parts, this third species was more similar to G. jiroveci than to G. pseudonemachili. The differences between G. jiroveci and the third species were mainly in the morphology of the marginal hook sickle, but included the total length of the marginal hook, the length of the hamulus point, the length of the marginal hook sickle, the width of the ventral bar, and the width of the dorsal bar. Based on comparison with the original material, the third species was identified as G. papernai Ergens & Bychowsky, 1967, which has recently been considered a synonym of G. jiroveci. These analyses provided sufficient evidence for the restoration of G. papernai as a valid taxon. Partial sequences of the internal transcribed spacer rRNA genes (ITS rDNA) verified the validity of all three Gyrodactylus species studied.

Tiny worms from a mighty continent: high diversity and new phylogenetic lineages of African monogeneans.

The family Gyrodactylidae contains one of the most significant radiations of platyhelminth fish parasites. The so-called hyperviviparity is very rare in the animal kingdom, and the rapid generation time can lead to an explosive population growth, which can cause massive losses in farmed fish. Here we present the first molecular phylogeny including all-but-one African genera, inferred from ITS and 18S rDNA sequences. The validity of nominal genera is discussed in relation to the systematic value of morphological characters traditionally used for generic identification. New complete 18S rDNA sequences of 18 gyrodactylid species of eight genera together with ITS rDNA gene sequences of eight species representing seven genera were generated and complemented with GenBank sequences. The maximum likelihood and Bayesian analyses pointed to a paraphyletic nature of African Gyrodactylus species. They formed well-supported clades possibly indicating speciation within host taxa: (1) parasites of cichlids (Cichlidae); (2) parasites of catfishes (Siluriformes), consisting of a lineage infecting mochokids and one infecting clariids. Macrogyrodactylus spp. firmly clustered into a monophyletic group. We found that Swingleus and Fundulotrema are very closely related and clearly cluster within Gyrodactylus. This supports earlier claims as to the paraphyly of the nominal genus Gyrodactylus as it is currently defined, and necessitates a revision of Swingleus and Fundulotrema. Molecular dating estimates confirmed a relatively young, certainly post-Gondwanan, origin of gyrodactylid lineages. Building on the previously suggested South-American origin of viviparous gyrodactylids, the dataset suggests subsequent intercontinental dispersal to Africa and from there repeated colonisation of the Holarctic. Even though the African continent has been heavily under sampled, the present diversity is far greater than in the intensively studied European fauna, probably because of the high endemicity of sub-Saharan Africa.

Gyrodactylus malalai sp. nov. (Monogenea, Gyrodactylidae) from Nile tilapia, Oreochromis niloticus (L.) and Redbelly tilapia, Tilapia zillii (Gervais) (Teleostei, Cichlidae) in the Lake Turkana, Kenya

Gyrodactylus malalai sp. nov. is described from the fin surface of cichlid fishes Oreochromis niloticus (L.) and Tilapia zillii (Gervais) caught in Lake Turkana (Kenya). The new species morphologically resembles Gyrodactylus nyanzae Paperna, 1973, but can be readily distinguished by the shape of the marginal hook sickles and the size of its hamuli. The sequence data of rDNA spanning partial 18S, internal transcribe spacer 1 and 2 and the 5.8S gene is unique within GenBank. Genetically, as most similar Gyrodactylus ergensi Přikrylová, Matějusová, Musilová et Gelnar, 2009 was found (97.5%). Moreover, a specimen of G. cichlidarum from O. niloticus, and a specimen G. ergensi from Sarotherodon galilaeus (L.) were collected during sampling in Kenya. Likewise, additional sampling of O. niloticus from the Blue Nile in Sudan revealed the presence of the newly described species. These findings represent the first records of gyrodactylids in both African countries.

The first record of Macrogyrodactylus species (Monogenea, Gyrodactylidae) on freshwater fishes in Senegal with the description of Macrogyrodactylus simentiensis sp. nov., a parasite of Polypterus senegalus Cuvier

The first record of monogenean parasites of the genus Macrogyrodactylus Malmberg, 1957 on freshwater fish in Senegal is presented. Macrogyrodactylus congolensis Prudhoe, 1957 from the skin and Macrogyrodactylus heterobranchii N’Douba et Lambert, 1999 from the gills of Clarias anguillaris L. were found, representing new host records for these parasites. On Polypterus senegalus Cuvier, three Macrogyrodactylus species were identified, Macrogyrodactylus polypteri Malmberg, 1957, Macrogyrodactylus simentiensis sp. nov. and Macrogyrodactylus sp. M. simentiensis sp. nov. can be readily distinguished from the other Macrogyrodactylus species by the size of its hamuli and the shape of its marginal hook sickles. The marginal hooks on the anterolateral lobes of M. simentiensis differ in size and shape from those on the posterior margin of the haptor. Measurements and drawings of the haptoral sclerites of all five identified species are provided.

European distribution for metacercariae of the North American digenean Posthodiplostomum cf. minimum centrarchi (Strigeiformes: Diplostomidae)

Metacercariae of a North American digenean Posthodiplostomum cf. minimum centrarchi (Strigeiformes: Diplostomidae), have been reported from seven localities in Europe, with cysts recorded in the mesentery and internal organs of two invasive non-indigenous fishes (Lepomis gibbosus and Micropterus salmoides) from sites in Bulgaria, the Czech Republic and Portugal. Analysis of rDNA locus ITS1-ITS2-28S confirmed a closer relationship to the American Posthodiplostomum species than the common European species P. cuticola or P. brevicaudatum. Our data indicate limited potential of this parasite for switch to local fish fauna and confirm the occurrence at distant sites across Europe, suggesting that birds as definitive parasite hosts may play an important role for parasite dispersal. Further detailed studies are needed to confirm the actual means of introduction to Europe.