Quadriacanthus species (Monogenea: Dactylogyridae) from catfishes (Teleostei: Siluriformes) in eastern Africa: new species, new records and first insights into interspecific genetic relationships

Abstract

BackgroundAfrican catfishes of the families Bagridae and Clariidae are known to be parasitized with monogeneans of Quadriacanthus Paperna, 1961 (Dactylogyridae). The genus remains taxonomically challenging due to its speciose nature and relatively wide host range representing two fish orders, i.e. Siluriformes and Osteoglossiformes, in Africa and Asia. Here, we investigated diversity of Quadriacanthus spp. parasitizing Clarias gariepinus (Burchell), Heterobranchus bidorsalis Geoffroy Saint-Hilaire, and Bagrus docmak (Forsskål) collected in the Lake Turkana (Kenya) and Nile River Basin (Sudan). The interspecific relationships among Quadriacanthus spp. parasitizing catfishes inferred from ribosomal DNA sequences were investigated for the first time.MethodsA combined morphological and molecular approach was used for description of the new species and for a critical review of the previously described Quadriacanthus spp., by means of phase contrast microscopic examination of sclerotized structures, and assessing the genetic divergence among the species found using rDNA sequences.ResultsSeven species (including four new) of Quadriacanthus were identified. These were as follows: Quadriacanthus aegypticus El-Naggar & Serag, 1986, Quadriacanthus clariadis Paperna, 1961, Quadriacanthus fornicatus n. sp., Quadriacanthus pravus n. sp., and Quadriacanthus zuheiri n. sp. from Clarias gariepinus (Clariidae); Quadriacanthus mandibulatus n. sp. from Heterobranchus bidorsalis (Clariidae); and Quadriacanthus bagrae Paperna, 1979 from Bagrus docmak (Bagridae). For both 18S-ITS1 and 28S rDNA regions, Q. clariadis from a clariid fish was found to be most closely related to Q. bagrae from a bagrid host. Quadriacanthus mandibulatus n. sp. was observed to be the most distant species from the others. The separation of Q. mandibulatus n. sp. from the other species corresponds with the different morphology of its copulatory tube. The copulatory tube is terminally enlarged in Q. mandibulatus n. sp., while the tube in all other congeners studied is comparatively small and with an oblique tapering termination.ConclusionsThis study contributes to a better understanding of African dactylogyrid diversity and provides the first molecular characterization of Quadriacanthus spp. The observed interspecific genetic relationships among Quadriacanthus spp. from clariids and Q. bagrae from a bagrid host suggest a possible host-switching event in the evolutionary history of the genus. Our records extend the currently known geographical range for Quadriacanthus spp. to Kenya and Sudan.

Species of Characidotrema Paperna & Thurston, 1968 (Monogenea: Dactylogyridae) from fishes of the Alestidae (Characiformes) in Africa: new species, host-parasite associations and first insights into the phylogeny of the genus

“…Thus, the basic structure of the MCO (along with host preferences) appears to be the best morphological tool for resolving relationships among species of Characidotrema . This result supports the MCO type concept [30] suggesting that the morphology of the MCO carries much information of systematic/phylogenetic importance and that species with a particular MCO type often parasitize a particular major host taxon [13, 31, 32]. However, C. ruahae (Paperna, 1979) from B. imberi is morphologically more similar to C. brevipenis and C. nursei from B. nurse [3] than to the two new species from B. imberi .…”

“…Monogeneans were collected from the gills of freshly killed fishes using fine needles and processed as in Francová et al [13]. Parasite specimens used for morphological study of the sclerotized structures (the haptoral and reproductive hard parts) were completely flattened using coverslip pressure and fixed with a mixture of glycerine and ammonium picrate (GAP).…”

Morphological and Morphometric Characterization of Four Monogenean Parasites from Fishes of the River Nile, Qena Governorate, Egypt

“…gariepinus Lake Galilee, Israel (Paperna, 1960 and1961), Q. kobiensis, Ha Ky, 1968from Cl. fuscus Linnaeus, 1758in Vietnam (Tripathi et al, 2007, and Quadriacanthus species from catfishes (Teleostei: Siluriformes) in eastern Africa (Francová et al, 2017). Intraspecific variations between the measurements of Q. bagrae in the present work and those registered previously were shown in Table (3).…”

The phylogenetic position ofAnacanthorus(Monogenea, Dactylogyridae) parasitizing Brazilian serrasalmids (Characiformes)

“…Using complete 18S rDNA sequences, Müller et al [45] showed that M. viatorum clustered with A. penilabiatus . Both ribosomal markers (28S and 18S rDNA) have been widely used to reconstruct the phylogenies of monogeneans, and in many cases they have produced similar topologies (e.g., Plaisance et al [51], Francová et al [15], Verma et al [66]); thus, the finding of Müller et al [45] is due to the lack of sequences of species closely related to Anacanthorus species (i.e., the absence of the representatives of freshwater Ancyrocephalinae).…”