Centrorhynchus spp. (Acanthocephala) in South America: new anuran record and checklist of vertebrate hosts

The aim of this study was to record Centrorhynchus sp. associated with the exotic species Aquarana catesbeiana (bullfrog) in southern Brazil and to present a checklist of vertebrate hosts in South America. Twenty-nine adults and juveniles of A. catesbeiana were collected in Capão do Leão, state of Rio Grande do Sul, Brazil, between October 2019 and December 2020. We found 275 specimens of Centrorhynchus sp. cystacanths in the stomach musculature and coelomic cavity of 55.1% of hosts (16). There was no significant differences in the prevalence and mean intensity of infection with cystacanths when compared males and females of A. catesbeiana. The prevalence was significantly higher in adults than in juveniles. The checklist presents 106 species of vertebrate hosts and 14 taxa of Centrorhynchus recorded in nine South American countries. Avian were the main definitive hosts of Centrorhynchus spp. and snakes Dipsadidae, anurans Hylidae and Leptodactylidae the main paratenic hosts in South America. This is the first record of Centrorhynchus cystacanths in A. catesbeiana in the South America. The study provides tools to help understand the parasitic relationships between species of Centrorhynchus and A. catesbeiana and other hosts in areas where bullfrog have been introduced.

Helminthological studies in francolins (Galliformes: Phasianidae) of Sindh, Pakistan with two new species and epidemiological parameters

Francolins are among the very gregarious variety of game birds severely infected by various parasites that may cause an important source for infection transmission in humans by eating them very fondly in the country. During this study, two commonly found francolins species of the region; Francolinus francolinus (Black Francolin) and F. pondicerianus (Grey Francolin), were examined for helminthes fauna. The study deals with the primary survey of helminthic infection occur in the francolin birds (Phasianidae: Perdicinae) with reference to their forage in gut content. It is the first helminthological and epidemiological study in Sindh, Pakistan. At present, a total of 20 birds were examined, out of which 17 were found infected with cestode larvae of two species of genus Cotugnia and genus Raillietina, one species of trematode, Prosthogonimus potentially new species; one new species of acanthocephalan, Mediorhynchus francolinae sp. nov.; one species of nematode, Subulura brumpti (López-Neyra, 1922) were recovered, with new host records. The forage content and comparative incidence of helminth species were also observed and discussed in the current study, which revealed the high prevalence of infection in grey francolins than that of black francolin. The mean intensity of infection relative to the forage in guts of hosts was found significant (P < 0.05), observed 9.14 ± 1.65 in black francolins than in grey francolins (5.8 ± 0.51). The parasitic abundance was compared using Fisher's Exact Test, which showed no significant difference between cestodes and nematodes in the two hosts, however trematode and acanthocephalan was found only in grey francolin. The parasitic frequencies along with the confidence intervals were recorded higher in black francolins by cestodes and nematodes than the black francolins during the present study.

Morphological and genetic characterisation of Centrorhynchus clitorideus (Meyer, 1931) (Acanthocephala: Centrorhynchidae) from the little owl Athene noctua (Scopoli) (Strigiformes: Strigidae) in Pakistan

Centrorhynchus Lühe, 1911 is a large genus of acanthocephalans mainly parasitic in various strigiform and falconiform birds. Some species of Centrorhynchus have not been adequately described. Here, the detailed morphology of C. clitorideus (Meyer, 1931) was studied using light and, for the first time, scanning electron microscopy, based on newly collected specimens from the little owl Athene noctua (Scopoli) (Strigiformes: Strigidae) in Pakistan. Partial sequences of the 18S and 28S nuclear ribosomal RNA genes and the mitochondrial cytochrome c oxidase subunit 1 (cox1) of C. clitorideus were generated for the first time. No nucleotide variation was detected for the partial 18S and 28S regions, but 3.30% of intraspecific nucleotide divergence was found for the cox1 gene. Phylogenetic analyses based on 28S and 18S sequence data showed that C. clitorideus formed a sister relationship with Centrorhynchus sp. MGV-2005 or Centrorhynchus sp. MGV-2005 + C. microcephalus (Bravo-Hollis, 1947), respectively.

Characterization of the complete mitogenome of Centrorhynchus clitorideus (Meyer, 1931) (Palaeacanthocephala: Centrorhynchidae), the largest mitochondrial genome in Acanthocephala, and its phylogenetic implications

Species of Centrorhynchus (Polymorphida: Centrorhynchidae) commonly parasitize various falconiform and strigiform birds worldwide. In the present study, the complete mitochondrial (mt) genome sequences of Centrorhynchus clitorideus was sequenced and annotated for the first time based on specimens collected from the little owl Athene noctua (Scopoli) (Strigiformes: Strigidae) in Pakistan. The complete mt genome sequences of C. clitorideus is 15,884 bp in length, and contained 36 genes [two rRNA genes (rrnL and rrnS), 22 tRNA genes and 12 protein-coding genes (PCGs) (lacking atp8)] and two non-coding regions (NCR1 and NCR2), which represents the largest mt genome of acanthocephalan reported so far. In order to assess the systematic position of C. clitorideus and the interrelationship of the family Centrorhynchidae and the other families in order Polymorphida, the phylogenetic tree was constructed using Bayesian inference (BI) based on amino acid sequences of 12 PCGs. Phylogenetic results supported C. clitorideus formed a sister relationship to C. milvus in Centrorhynchidae, which has a sister relationship to the representatives of Polymorphidae + Plagiorhynchidae. Our results revealed the monophyly of Polymorphida and paraphyly of Echinorhynchida in the class Palaeacanthocephala. The validity of the genus Sphaerirostris (Polymorphida: Centrorhynchidae) was also challenged by our phylogenetic results, which seems to be a synonym of Centrorhynchus. Moreover, the present phylogenetic analysis indicated that the family Quadrigyridae and subfamily Pallisentinae (A. cheni and P. celatus) are polyphyletic.

Characterization of the complete mitochondrial genome of Centrorhynchus milvus (Acanthocephala: Polymorphida) and its phylogenetic implications

The phylum Acanthocephala is a small group of obligate parasites of animals. However, the current classifications of Acanthocephala are still under debate. Moreover, our present knowledge of the complete mitochondrial genome of this parasite group remains limited. To fill this knowledge gap, the complete mitochondrial (mt) genome of Centrorhynchus milvusWard, 1956 (Palaeacanthocephala: Polymorphida) was firstly sequenced and determined based on specimens collected from the red kite (Milvus milvus) in Pakistan. The mitochondrial genome of C. milvus is 14,314 bp in length and contains 36 genes, including 12 protein-coding (PCGs) genes, 22 transfer RNA (tRNA) genes and ribosomal RNA (rRNA) genes (rrnL and rrnS). To elucidate the phylogenetic relationships of the four classes of Acanthocephala and the systematic position of C. milvus, phylogenetic analysis based on concatenated amino acid sequences of 12 PCGs was performed using Bayesian inference (BI). The results supported the monophyly of Archiacanthocephala and Palaeacanthocephala with strong support (BPP = 1) and also indicated that Archiacanthocephala is the sister clade to the remaining classes of Acanthocephala (Palaeacanthocephala, Eoacanthocephala and Polyacanthocephala). However, Polyacanthocephala with only one representative species (P. caballeroi) is nested within Eoacanthocephala. Our phylogenetic analysis also confirmed C. milvus as the member of the family Centrorhynchidae with a sister relationship to C. aluconis. Our present mt genomic data are very useful for studying the molecular epidemiology, population genetics and systematics of acanthocephalans.

Checklist of acanthocephalan parasites of South Africa

Twenty-one species of acanthocephalans, representative of thirteen genera from ten families of seven orders and three classes, are included in this updated checklist of acanthocephalans in South Africa.

Although South Africa appears to have a less diverse acanthocephalan fauna compared to some other countries such as Iran in Asia, or Brazil in South America, this is probably an artefact of fewer parasitological surveys.