Summary1. Because host-parasite interactions are so ubiquitous, it is of primary interest for ecologists to understand the factors that generate, maintain and constrain these associations. Phylogenetic comparative studies have found abundant evidence for host-switching to relatively unrelated hosts, sometimes related to diversification events, in a variety of host-parasite systems. For Monogenoidea (Platyhelminthes) parasites, it has been suggested that the co-speciation model alone cannot explain host occurrences, hence host-switching and/or non-vicariant modes of speciation should be associated with the origins and diversification of several monogenoid taxa. 2. The factors that shape broad patterns of parasite sharing were investigated using path analysis as a way to generate hypotheses about the origins of host-parasite interactions between monogenoid gill parasites and Neotropical freshwater fishes. 3. Parasite sharing was assessed from an interaction matrix, and explanatory variables included phylogenetic relationships, environmental preferences, biological traits and geographic distribution for each host species. 4. Although geographic distribution of hosts and host ecology are important factors to understand host-parasite interactions, especially within host lineages that share a relatively recent evolutionary history, phylogeny had the strongest overall direct effect on parasite sharing. 5. Phylogenetic contiguity of host communities may allow a 'stepping-stone' mode of hostswitching, which increases parasite sharing. Our results reinforce the importance of including evolutionary history in the study of ecological associations, including emerging infectious diseases risk assessment.

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The study of biological invasions can be roughly divided into three parts: detection, monitoring, mitigation. Here, our objectives were to describe the marine fauna of the area of the port of São Sebastião (on the northern coast of the state of São Paulo, in the São Sebastião Channel, SSC) to detect introduced species. Descriptions of the faunal community of the SSC with respect to native and allochthonous (invasive or potentially so) diversity are lacking for all invertebrate groups. Sampling was carried out by specialists within each taxonomic group, in December 2009, following the protocol of the Rapid Assessment Survey (RAS) in three areas with artificial structures as substrates. A total of 142 species were identified (61 native, 15 introduced, 62 cryptogenic, 4 not classified), of which 17 were Polychaeta (12, 1, 1, 3), 24 Ascidiacea (3, 6, 15, 0), 36 Bryozoa (17, 0, 18, 1), 27 Cnidaria (2, 1, 24, 0), 20 Crustacea (11, 4, 5, 0), 2 Entoprocta (native), 16 Mollusca (13, 3, 0, 0). Twelve species are new occurrences for the SSC. Among the introduced taxa, two are new for coastal Brazil. Estimates of introduced taxa are conservative as the results of molecular studies suggest that some species previously considered cryptogenic are indeed introduced. We emphasize that the large number of cryptogenic species illustrates the need for a long-term monitoring program, especially in areas most susceptible to bioinvasion. We conclude that rapid assessment studies, even in relatively wellknown regions, can be very useful for the detection of introduced species and we recommend that they be carried out on a larger scale in all ports with heavy ship traffic.

Estuarine chaetognath population dynamics are poorly known worldwide. We have conducted eight seasonal campaigns (October 2007–August 2008) sampling three sectors in the subtropical Babitonga Bay estuary (26°S 48°W) in order to depict chaetognath abundance and population structure dynamics and test the influence of hydrography and food availability and type. Of three species sampled, Parasagitta friderici represented >93% of abundance in all samples and was examined in detail. There were no differences in P. friderici abundance between the sectors of the estuary, related to its high tolerance to low salinity, a feature not common for most chaetognath species. Salinity tolerance is an important adaptive characteristic to thrive within estuarine systems, and probably is responsible for the dominance of P. friderici in coastal and brackish water environments throughout most of its distribution. Juveniles dominated the population most of the year, except in February–April when abundances were lower and adults predominated. These results suggest that recruitment occurs continuously throughout the year, being more intense between October and January (spring to early summer) and in May (autumn) when densities and proportion of juveniles were higher. General Additive Models suggest that temperature and zooplankton biomass are significant (P < 0.05) factors influencing juvenile abundance while only the latter influenced the adults. We conclude that food availability is the most important driver in the studied population of P. friderici and recruitment peaks, which lead to high densities, seem to occur following peaks of their copepod prey along with particular temperature conditions (22–23°C).

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Poster session 3, September 23, 2022, 12:30 PM - 1:30 PM Sporotrichosis is a neglected tropical disease caused by fungi of the genus Sporothrix spp. Transmission can occur through sapronotic, enzootic, and zoonotic pathways. Sporothrix schenckii and S. brasiliensis are the most common etiologic agents in human and animal diseases in Brazil. Objectives The objective of this work is to alert about the emergence of feline sporotrichosis on the Brazilian side of the Southern Triple Border (Brazil, Paraguay, and Argentina). Methods From July 2021 to March 2022, biological samples and clinical-epidemiological data were collected from 57 domestic cats with typical sporotrichosis lesions and residents of Iguassu Falls (Foz). The cats were selected through notification of the citizens themselves, health agents of Zoonosis Control Center of Iguassu Falls (CCZ–Foz), veterinarians from private veterinary clinics and hospitals, and the receipt of suspected animals by CCZ–Foz. From the samples, direct mycological examinations and fungal culture were performed and a set of 10 fungal isolates from the microbiological tests were selected for molecular analysis based on calmodulin (CAL) gene sequences. From each collection point, the geographic coordinate was taken using the Google Earth® software and the Quantus Gis software (QGIS) was used to assemble the maps. Results Of the 57 samples collected, 45 were considered positive in the microbiological tests (Fig. 1), and the first 10 isolates were identified as S. brasiliensis. Based on clinical-epidemiological, and geographic data (Fig. 2), the following problems associated with feline sporotrichosis in this region were identified: the presence of sporotrichosis positive cats in high-density regions population of Foz; the epidemic profile of the disease with cases spreading quickly by neighborhoods in the South region of the city to neighborhoods in the North region; the easy access to the street and other homes of infected cats, which facilitates the zoonotic and enzootic transmission cycle of this disease; the free movement of animals positive for backyards and vacant lots where they can defecate and even come to death the that feeds the sapronotic cycle; and the profile most associated with the animal positive being that of an uncastrated male, not vaccinated and with little or no access to veterinary services. Conclusion For being a region of the Triple Frontier, there are many differences in political, administrative, and operational between the Public Health Systems of the three countries, with Paraguay and Argentina, the political-administrative-operational centralization is configured as a great node critical for the development of health actions in an adequate way to the needs at a loco-regional level and, above all, on time for the implementation thereof. With the situational diagnosis provided for this study it is possible to understand the factors that influence the emergence of the disease in Iguassu Falls contributing to the development of programs and specific strategies, focusing on raising the population's awareness of safekeeping practices for your animals; free diagnosis for animals (dogs and cats) suspected of sporotrichosis, and treatment with a free supply of medication for patients animals with a confirmed diagnosis of sporotrichosis.

Gyrodactylus superbus (Szidat, 1973) Popazoglo & Boeger, 2000 was described from Corydoras paleatus (Jenyns) (Callichthyidae) and represents the only known viviparous gyrodactylid reported from the Parano-Platense basin of Argentina. We describe two new species of viviparous neotropical gyrodactylids parasitizing the introduced poeciliid, Cnesterodon decemmaculatus (Jenyns, 1842) (Poeciliidae), from southern Argentina: Gyrodactylus decemmaculati n. sp. and Gyrodactylus breviradix n. sp. The new species differ from other gyrodactylids parasitizing poeciliids in the morphology of superficial bars and hooklets. Gyrodactylus decemmaculati n. sp. has a superficial bar with two robust and rounded anterolateral projections (each with a ventral lobe), and a subtriangular shield, and has a slender hooklet with a delicate recurved point, a straight, elongate shaft, and a depressed, acute toe. Gyrodactylus breviradix n. sp. has a superficial bar with two robust, elongate anterolateral projections, folded inward, and a trapezoidal shield, and has a hooklet with a short point, angled at 90º, ending before level of toe tip, a straight, short shaft, a round, prominent heel, and a pointed, depressed toe. These identifications were supported by DNA analyses based on sequences of the ITS2 region and a barcoding gap analysis. Sequences of the Cytochrome oxidase II gene and fragments of the Internal Transcribed Spacers 1 for both species are also provided.

This study aimed to enhance our understanding in monogenoid evolution by using morphological and molecular data to determine kinship relationships between species and changes in morphological structures over time. We focused on variations in characteristics among the organisms of the family Gyrodactylidae, concentrating on the phylogenetic position of Polyclithrum with other genera in the family. We collected specimens of Polyclithrum from the striped mullet, Mugil cephalus and Swingleus, and Fundulotrema specimens from mummichog Fundulus heteroclitus in estuarine systems of South Carolina, United States. In addition, we analyzed them and other genera (including e.g., Mormyrogyrodactylus, Gyrodactyloides, and Macrogyrodactylus) using both morphological and molecular (18S rDNA) approaches. We performed phylogenetic trees based on Maximum Parsymony, Maximum Likelihood and Bayesian Inference, and constructed a character morphological matrix by Parsimony Reconstruction of Ancestral Character States method. Our results suggest a homoplastic origin with evolutionary convergences in characters, revealing that there is inconsistency between our data and previously published works based solely on morphological structures of the group. The homoplasy scenario found in Gyrodactylidae can be a result of the limited set of putative homologous morphological features. However, differences between the phylogenies based on morphology and those based on molecular data may arise from both databases. While morphology remains essential in understanding the evolution of this group, molecular data, otherwise, provide a less biased source of information for constructing phylogenetic hypotheses. Combining these data facilitates a better comprehension of the homologous status of morphological features and to understand Gyrodactylidae evolutionary history.