Species of Annulotrema (Monopisthocotylea, Dactylogyridae) parasitising African tetras (Characiformes, Alestidae) in the Phongolo River, South Africa with the description of four new species

Species of Alestidae are known to be parasitised by dactylogyrid monogeneans representing three genera, Afrocleidodiscus Paperna, 1969, Annulotrema Paperna & Thurston, 1969, and Characidotrema Paperna & Thurston, 1968. The objective of the present study was to investigate the species diversity of Monopisthocotylea of African tetras from the Lower Phongolo River and floodplain in South Africa. Four new and two previously described species of Annulotrema were identified from the gills of three species of African tetras, Brycinus imberi, Hydrocynus vittatus, and Micralestes acutidens. The collected parasites were studied using two complementary approaches: morphology of hard sclerotised structures, and molecular markers using rDNA sequence data (28S rDNA, 18S rDNA, and ITS1). Three new species, Annulotrema arcum n. sp., Annulotrema caputfemoris n. sp., and Annulotrema strepsiceros n. sp., were described from B. imberi and one species, Annulotrema retortum n. sp., from M. acuditens. Two previously described species, Annulotrema pikoides Guégan, Lambert and Birgi, 1988 and A. pseudonili Kičinjaová and Řehulková, 2017, were newly recorded from H. vittatus in South Africa. Annulotrema arcum n. sp. and A. caputfemoris n. sp. share similar male copulatory organ morphologies, suggesting a close phylogenetic relationship as sister taxa. Despite weak nodal support, A. strepsiceros n. sp. shows morphological congruence with the former two species, reinforcing their molecular linkage. The present study shows a critical need for the exploration of monopisthocotylean diversity and the paucity of available molecular data of representatives from this group.

Oncoceratium amphidactylum n. gen. n. sp. (Monogenoidea: Gyrodactylidae) from Hoplosternum littorale (Hancock) (Siluriformes, Callichthyidae) from southeastern Brazil

Oncoceratium n. gen. is proposed to accommodate Oncoceratium amphidactylum n. gen. n. sp. (Monogenoidea, Gyrodactylidae). Although the proposed genus is monotypic, the differences presented in the diagnosis clearly establish it as distinct from species from other genera, such as Gyrodactylus von Nordmann, 1832 and especially those that occur exclusively in the Neotropical region. The new genus is diagnosed by the presence of a bulbous male copulatory organ, with one row of spinelets of similar sizes and shapes, while the only spine usually found in the gyrodactylids is absent or not differentiated; a haptor with anchors presenting points folded outwards, and superficial and deep roots continuous and indistinguishable; the absence of a deep bar; and hooks in two bilateral clusters of eight hooks. Oncoceratium amphidactylum n. gen. n. sp. is described from the tamboatá fish, Hoplosternum littorale (Hancock) (Callichthyidae), and is characterized by the presence of a pair of horn-shaped anchors with the point turned outwards, a superficial bar shield and absent deep bar, hooks disposed in bilateral lobes, and a MCO with no spine or with a row with large spinelets visible in place of the spine. In addition to the morphological features, distance analysis and Bayesian inference, based on 5.8s and partial ITS2, support placing the new species in a new genus, and not including it in a cluster of species of Gyrodactylus and near to Gyrodactyloides bychowskii Albova, 1948, Ieredactylus rivuli Schelkle et al., 2011 and Laminiscus gussevi (Bychowsky & Polyansky, 1953) Pálsson & Beverely-Burton, 1983.

Review of the metazoan parasites of the economically and ecologically important African sharptooth catfish Clarias gariepinus in Africa: Current status and novel records

One of the most widely distributed African freshwater fish is the African sharptooth catfish Clarias gariepinus (Burchell) that is naturally distributed in 8 of the 10 ichthyofaunal regions of this continent. Clarias gariepinus is a highly valued and cheap staple to local communities and an ideal aquaculture species. Consequently, interest in the parasitic communities of C. gariepinus has increased as parasites may accidentally be ingested by humans when eating uncooked fish or can be introduced into culture systems through fish stocks supplied from local rivers which affect yield, growth, and marketability. This review provides an overview of the ∼107 metazoan parasite species known to parasitise C. gariepinus in Africa and their general life cycles, morphology, paratenic and post-cyclic infections, and the biogeography and validity of records are discussed. A brief overview is included on the application of some of these parasites in environmental studies and their link to human health.

Description of Tresuncinidactylus wilmienae gen. et sp. n. (Monogenea: Gyrodactylidae), from the gills of the bulldog, Marcusenius macrolepidotus (Peters) from Lake Kariba, Zimbabwe

The African continent has a rich diversity of fish and amphibians in its inland water systems that serve as hosts for monogeneans of seven genera of the Gyrodactylidae van Beneden et Hesse, 1832. In August 2011, eight gyrodactylid parasites were collected from the gills of two specimens of bulldog, Marcusenius macrolepidotus (Peters), from Lake Kariba, Zimbabwe. Morphometric evaluation and sequencing of 18S rDNA confirmed that the specimens represented a species of a new viviparous genus, Tresuncinidactylus wilmienae gen. et sp. n. The attachment apparatus consists of a single pair of large slender hamuli with prominently flattened roots that are connected by a simple, narrow dorsal bar. The ventral bar is small and possesses a thin lingulate membrane but no evident anterolateral processes. There are 16 marginal hooks of one morphological type, but of three different sizes, with large falculate sickles that are proportionaly equal in length to the length of their handles. The two largest pairs of marginal hooks are positioned closest to the opisthaptoral peduncle, the neighbouring two pairs of medium-sized marginal hook sickles are situated along the lateral margins of the opisthaptor. Four pairs of smallest marginal hooks are positioned along the posterior margin of the opisthaptor. The male copulatory organ consists of a muscular pouch armed with approximately 30 gracile spines. Phylogenetic analyses of partial sequences of the 18S rDNA using Maximum Likelihood and Bayesian Inference placed the new genus within the lineage of solely African genera and suggests Afrogyrodactylus Paperna, 1968, Citharodactylus Přikrylová, Shinn et Paladini, 2017 and Mormyrogyrodactylus Luus-Powell, Mashego et Khalil, 2003 as genera most closely related to the new genus.

Dactylogyrids (Platyhelminthes: Monogenea) from Sudanese Labeo Spp., with a Description of Dogielius Sennarensis n. Sp. and a Redescription of Dogielius Flosculus Guégan, Lambert & Euzet, 1989

Dactylogyrid monogeneans of Labeo horie Heckel, 1847 and L. niloticus (Linnaeus, 1758) (Cyprinidae) were surveyed at two sites on the River Nile in Sudan. The present study reports the presence of ten species of Dactylogyrus Diesing, 1850 and three species of Dogielius Bychowsky, 1936 based on a morphometric evaluation of the sclerotised structures. The species found include: Dactylogyrus nathaliaeGuégan, Lambert & Euzet, 1988; D. rastellusGuégan, Lambert & Euzet, 1988; D. retroversusGuégan, Lambert & Euzet, 1988; D. senegalensisPaperna, 1969, D. yassensisMusilová, Řehulková & Gelnar, 2009 and five other undescribed species of Dactylogyrus. The genus Dogielius was represented by Dogielius flosculusGuégan, Lambert & Euzet, 1989; the newly identified D. sennarensis n. sp., and one undescribed Dogielius species. While D. sennarensis n. sp. resembles D. intorquens, it differs from this species and other congeners by having a longer ventral bar and anchor points and nosclerotised vagina. In addition, this study redescribes D. flosculus based on the morphology of specimens collected from L. horie. All specimens studied had a single large vagina, in contrast to the original description which reported a vagina composed of two unconnected parts. All dactylogyrid species in this study represent new host and geographical records.

Description of Citharodactylus gagei n. gen. et n. sp. (Monogenea: Gyrodactylidae) from the moon fish, Citharinus citharus (Geoffroy Saint-Hilaire), from Lake Turkana

A new genus and species of monogenean belonging to the Gyrodactylidae, Citharodactylus gagei n. gen. et n. sp. (Plathyhelminthes, Monogenea), is described from the gills of the moon fish, Citharinus citharus (Geoffroy Saint-Hilaire), a characiform fish collected from Lake Turkana in northern Kenya. The new viviparous genus can be readily distinguished from the six other gyrodactylid genera recorded from Africa and from the other viviparous genera within the Gyrodactylidae based on the morphology of the male copulatory organ (MCO), which consists of a muscular ovate organ with an opening onto the tegument through which the narrow tapered end of a sclerotised curved cone-shaped structure protrudes. The tegumental opening of the MCO is surrounded by a collar of short spines. Sequencing of the nuclear ribosomal DNA internal transcribed spacers 1 and 2, the 5.8S and the 18S rDNA genes and a comparison with the gyrodactylid species listed in GenBank confirmed the specimens are unique and do not match with any existing entry. When phylogenies for each genomic region were conducted (i.e. 0.064 gamma-corrected pairwise genetic distance based on a alignment of 1750 bp of the 1857 bp long 18S rDNA gene), the most similar match was that of Afrogyrodactylus sp. [= A. girgifae (Folia Parasitol 61:529-536, 2014)] from Brycinus nurse (Rüppell). The proposed name of the new parasite is Citharodactylus n. gen. which represents the seventh gyrodactylid genus to be found in Africa and the 25th viviparous genus and the 32nd genus to be added to the Gyrodactylidae.