Life history strategies of Cotylurus spp. Szidat, 1928 (Trematoda, Strigeidae) in the molecular era - Evolutionary consequences and implications for taxonomy.

Species of Cotylurus Szidat, 1928 (Diplostomoidea: Strigeidae) are highly specialized digeneans that parasitize the gastrointestinal tract and bursa of Fabricius of water and wading birds. They have a three-host life cycle; the role of first intermediate host is played by pulmonate snails, while a wide range of water snails (both pulmonate and prosobranch) and leeches are reported as second intermediate hosts. Unfortunately, species richness, molecular diversity and phylogeny of metacercariae of Cotylurus spp. (tetracotyle) occurring in snails remain poorly understood. Thus, we have performed the parasitological and taxonomical examination of tetracotyles form freshwater snails from Poland, supplemented with adult Strigeidae specimens sampled from water birds. In this study we report our use of recently obtained sequences of two molecular markers (28S nuclear large ribosomal subunit gene (28S rDNA) and the cytochrome c oxidase subunit 1 (CO1) fragment), supplemented by results of a method of species delimitation (GMYC) and haplotype analysis to analyse some aspects of the ecology, taxonomy, and phylogeny of members of the genus Cotylurus. The provided phylogenetic reconstructions discovered unexpectedly high molecular diversity within Cotylurus occurring in snails, with clearly expressed evidence of cryptic diversity and the existence of several novel-species lineages. The obtained results revealed the polyphyletic character of C. syrius Dubois, 1934 (with three separate molecular species-level lineages) and C. cornutus (Rudolphi, 1809) Szidat, 1928 (with four separate molecular species-level lineages). Moreover, we demonstrated the existence of two divergent phylogenetical and ecological lineages within Cotylurus (one using leeches and other snails as second intermediate hosts), differing significantly in their life history strategies.

Leeches as the intermediate host for strigeid trematodes: genetic diversity and taxonomy of the genera Australapatemon Sudarikov, 1959 and Cotylurus Szidat, 1928.

BACKGROUND: Leeches (Hirudinida) play a significant role as intermediate hosts in the circulation of trematodes in the aquatic environment. However, species richness and the molecular diversity and phylogeny of larval stages of strigeid trematodes (tetracotyle) occurring in this group of aquatic invertebrates remain poorly understood. Here, we report our use of recently obtained sequences of several molecular markers to analyse some aspects of the ecology, taxonomy and phylogeny of the genera Australapatemon and Cotylurus, which utilise leeches as intermediate hosts. METHODS: From April 2017 to September 2018, 153 leeches were collected from several sampling stations in small rivers with slow-flowing waters and related drainage canals located in three regions of Poland. The distinctive forms of tetracotyle metacercariae collected from leeches supplemented with adult Strigeidae specimens sampled from a wide range of water birds were analysed using the 28S rDNA partial gene, the second internal transcribed spacer region (ITS2) region and the cytochrome c oxidase (COI) fragment. RESULTS: Among investigated leeches, metacercariae of the tetracotyle type were detected in the parenchyma and musculature of 62 specimens (prevalence 40.5%) with a mean intensity reaching 19.9 individuals. The taxonomic generic affiliation of metacercariae derived from the leeches revealed the occurrence of two strigeid genera: Australapatemon Sudarikov, 1959 and Cotylurus Szidat, 1928. Phylogenetic reconstructions based on the partial 28S rRNA gene, ITS2 region and partial COI gene confirmed the separation of the Australapatemon and Cotylurus clades. Taking currently available molecular data and our results into consideration, recently sequenced tetracotyle of Australapatemon represents most probably Au. minor; however, unclear phylogenetic relationships between Au. burti and Au. minor reduce the reliability of this conclusion. On the other hand, on the basis of the obtained sequences, supplemented with previously published data, the metacercariae of Cotylurus detected in leeches were identified as two species: C. strigeoides Dubois, 1958 and C. syrius Dubois, 1934. This is the first record of C. syrius from the intermediate host. CONCLUSIONS: The results of this study suggest the separation of ecological niches and life cycles between C. cornutus (Rudolphi, 1808) and C. strigeoides/C. syrius, with potential serious evolutionary consequences for a wide range of host-parasite relationships. Moreover, phylogenetic analyses corroborated the polyphyletic character of C. syrius, the unclear status of C. cornutus and the separate position of Cotylurus raabei Bezubik, 1958 within Cotylurus. The data demonstrate the inconsistent taxonomic status of the sequenced tetracotyle of Australapatemon, resulting, in our opinion, from the limited availability of fully reliable, comparative sequences of related taxa in GenBank.

Causes of Fatal Cyathostomiasis in Brown Booby (Sula leucogaster) from Brazil: Identification of Pathogen and Implications for Management.

Fatal infection by Cyathostoma (Cyathostoma) phenisci (Nematoda: Syngamidae), was identified in 2 of 52 brown boobies (Sula leucogaster) collected on beaches in the state of Rio de Janeiro, Brazil, and admitted to the veterinary clinic for rehabilitation. Both infected birds were in poor physical condition, with atrophied pectoral muscles, and died soon after starting treatment. The parasitological and pathological examination of the carcasses revealed the presence of C. (C.) phenisci in the trachea, resulting in tracheitis, as well as severe parasitic granulomatous bronchopneumonia caused by eggs deposited in the lungs. In our opinion, these serious pathological changes were the primary cause of chronic respiratory illness. This is the first description of fatal cyathostomiasis in a fish-eating avian host caused by infection by a member of the subgenus Cyathostoma (Cyathostoma). Therefore, it is reasonable to consider C. (C.) phenisci to be a real threat to a wide range of their definitive hosts, and cyathostomiasis should be considered in the differential diagnosis for fish-eating marine birds, even in cases without respiratory signs. This is also the first record of the genus Cyathostoma in Brazil.

On the systematic position of Collyricloides massanae Vaucher, 1969 (Platyhelminthes: Digenea) with notes on distribution of this trematode species.

The systematic position of the Collyricloides massanae, a rare cyst-dwelling parasite, located on intestinal wall of European birds and rodents, have always been controversial. Based on newly obtained sequences of the 28 sDNA of C. massanae from avian and rodent host from Central Europe, and on the previously published sequences of several genera and families among Microphalloidea, we evaluate its taxonomic position and the phylogenetic relationships within the genera Collyriclum Kossack, 1911 and Collyricloides Vaucher, 1969 which form the family Collyriclidae Ward, 1917. In the cladogram, C. massanae appears among the Pleurogenidae, forming a clade with Gyrabascus amphoraeformis (Modlinger, 1930) and Cortrema magnicaudata (Bykhovskaya-Pavlovskaya, 1950). We reject the commonly accepted placement of Collyricloides as the sister genus to Collyriclum within the Collyriclidae. Besides, we present and discuss the unusual records of C. massanae in the bank vole Myodes glareolus from northeastern Poland.