Centrorhynchus nahuelhuapensis n. sp. (Acanthocephala: Centrorhynchidae) from rufous-legged owl (Strix rufipes King) in Patagonia

Helminth Parasites of the Crane Hawk Geranospiza caerulescens (Vieillot) (Aves: Accipitridae) from Argentina, with the Description of a New Species of Parastrigea (Digenea: Strigeidae)

PURPOSE

The goal of this work was to increase the knowledge of the parasitic helminths of the Crane hawk, Geranospiza caerulescens.

METHODS

Two specimens of the Crane hawk were captured in Formosa province, Argentina, their viscera were preserved in 10% formalin and examined in the laboratory.

RESULTS

Helminthological analysis revealed the presence of six helminth taxa (one Trematoda, four Nematoda, and one Acanthocephala). The morphometric study of these helminths and its comparison with previous reports, allowed us to describe a new species of Parastrigea (Digenea: Strigeidae) and report new host-parasite associations and geographical records. Parastrigea labiata n. sp. is mainly characterized by having forebody not divided and two long trumpet-shaped projections of dorsal lip, which emerge through the opening. Five taxa, previously known, Synhimantus (Dispharynx) resticula, Synhimantus (Synhimantus) rectus, Microtetrameres sp., Porrocaecum sp. and Centrorhynchus sp. are briefly described.

CONCLUSIONS

Previous parasitological studies on G. caerulescens were carried out on material collected between 1817 and 1955, and seven species of helminths were reported. In this study, the six taxa of helminths found constitute new host records, which shows the importance of contemporary studies about this host. All helminths found have heteroxenous life cycles and birds are infected by trophic transmission. Crane hawk's diet includes small vertebrates and to a lesser extent large arthropods. The finding of five helminth species that use invertebrates as intermediate hosts could indicate an important consumption of invertebrates. This research expands the helminthological inventory of Argentinean birds and the knowledge of the helminths of G. caerulescens.

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.

Morphological and molecular data reveal a new species of Lueheia (Acanthocephala: Plagiorhynchidae) from Turdus migratorius (Turdidae) in central Mexico and its phylogenetic implications within the family

Members of the genus Lueheia Travassos, 1919, are endoparasites of birds, particularly passerines, throughout the Americas. Adults of Lueheia sp., (Plagiorhynchidae Golvan, 1960; Porrorchinae Golvan, 1956) were recovered from the intestine of the American robin (Turdus migratorius phillipsi Bangs) in Mexico City, and two other species of acanthocephalans identified as Porrorchis nickoli, (Plagiorhynchidae: Porrorchinae) Salgado-Maldonado and Cruz-Reyes, 2002 and Centrorhynchus microcephalus (Bravo-Hollis, 1947) Golvan, 1956 (Centrorhynchidae Van Cleave, 1916), were recovered from the Virginia opossum (Didelphis virginiana Allen) and groove-billed ani (Crotophaga sulcirostris Swainson), respectively in southeastern Mexico. Specimens of three species were sequenced at two molecular markers, the small subunit (SSU) and large subunit (LSU) of the nuclear rDNA and compared with other sequences available in GenBank. Maximum likelihood and Bayesian inference analyses of the combined (LSU + SSU) dataset and each individual dataset revealed that the specimens of Lueheia sp. formed an independent lineage, which is recognized herein as a new species, Lueheia aztecae n. sp., representing the fifth species of the genus in the Americas, and the second in the Nearctic region. The new species can be morphologically distinguished from the other five species in the genus by having a cylindrical proboscis, armed with 24-26 longitudinal rows with 9-10 hooks each. Phylogenetic inference performed with the combined dataset consisting of two genes (LSU + SSU) revealed that Lueheia aztecae n. sp. and P. nickoli belonging to subfamily Porrorchinae, formed two independent lineages, indicating that the subfamily is paraphyletic. Porrorchis nickoli and C. microcephalus formed a clade with other species of the genus Centrorhynchus, suggesting that P. nickoli should be transferred to genus Centrorhynchus, to form C. nickoli n. comb. In addition, we briefly discuss the ecological associations between the members of the families Plagiorhynchidae and Centrorhynchidae.

Molecular characterisation of acanthocephalans from Australian marine teleosts: proposal of a new family, synonymy of another and transfer of taxa between orders

We provide molecular data (cox1, 18S rDNA and 28S rDNA) for 17 acanthocephalan species and 20 host-parasite combinations from Australian marine teleosts collected from off Queensland, Australia. Fourteen of these acanthocephalans are characterised with molecular data for the first time and we provide the first molecular data for a species of each of the genera Heterosentis Van Cleave, 1931, Pyriproboscis Amin, Abdullah & Mhaisen, 2003 and Sclerocollum Schmidt & Paperna, 1978. Using 18S and 28S rDNA sequences, the phylogenetic position of each newly sequenced species is assessed with both single-gene and concatenated 18S+28S maximum likelihood and Bayesian inference analyses. Additional phylogenetic analyses focusing on the genus Rhadinorhynchus Lühe, 1912 and related lineages are included. Our phylogenetic results are broadly consistent with previous analyses, recovering previously identified inconsistencies but also providing new insights and necessitating taxonomic action. We do not find sufficient evidence to recognise the Gymnorhadinorhynchidae Braicovich, Lanfranchi, Farber, Marvaldi, Luque & Timi, 2014 as distinct from the Rhadinorhynchidae Lühe, 1912. The family Gymnorhadinorhynchidae and its sole genus, Gymnorhadinorhynchus Braicovich, Lanfranchi, Farber, Marvaldi, Luque & Timi, 2014, are here recognised as junior synonyms of Rhadinorhynchidae and Rhadinorhynchus, respectively. The two species currently assigned to Gymnorhadinorhynchus are recombined as Rhadinorhynchus decapteri (Braicovich, Lanfranchi, Farber, Marvaldi, Luque & Timi, 2014) n. comb. and Rhadinorhynchus mariserpentis (Steinauer, Garcia-Vedrenne, Weinstein & Kuris, 2019) n. comb. In all of our analyses, Rhadinorhynchus biformis Smales, 2014 is found basal to the Rhadinorhynchidae + Transvenidae Pichelin & Cribb, 2001, thus resulting in a paraphyletic Rhadinorhynchidae. It appears that R. biformis may require a new genus and family; however, morphological data for this species are currently insufficient to adequately distinguish it from related lineages, thus we defer the proposal of any new higher-rank names for this species. Species of the genus Sclerocollum, currently assigned to the Cavisomidae Meyer, 1932, are found nested within the family Transvenidae. We transfer the genus Sclerocollum to the Transvenidae and amend the diagnosis of the family accordingly. The genera Gorgorhynchoides Cable & Linderoth, 1963 and Serrasentis Van Cleave, 1923, currently assigned to the Rhadinorhynchidae, are supported as sister taxa and form a clade in the Polymorphida. We transfer these genera and Golvanorhynchus Noronha, Fabio & Pinto, 1978 to an emended concept of the Isthomosacanthidae Smales, 2012 and transfer this family to the Polymorphida. Lastly, Pyriproboscis heronensis (Pichelin, 1997) Amin, Abdullah & Mhaisen, 2003, currently assigned to the Pomphorhynchidae Yamaguti, 1939, falls under the Polymorphida in our analyses with some support for a sister relationship with the Centrorhynchidae Van Cleave, 1916. As this species clearly does not belong in the Pomphorhynchidae and is morphologically and molecularly distinct from the lineages of the Polymorphida, we propose the Pyriprobosicidae n. fam. to accommodate it.