Rodney Kozlowiski de Azevedo

Acanthocephala, Annelida, Arthropoda, Myxozoa, Nematoda and Platyhelminthes parasites of fishes from the Guandu river, Rio de Janeiro, Brazil

Using information from all published reports and data collected during several parasitological surveys between April 2003 and September 2009, a checklist of the parasites of fishes from Guandu River, southeastern of Brazil was generated. A total of 85 parasite species, 54 named species (1 Acanthocephala, 1 Cestoda, 2 Crustacea, 13 Digenea, 11 Nematoda, 23 Monogenea and 3 Myxozoa) and 31 undetermined species (3 Acanthocephala, 2 Cestoda, 1 Crustacea, 8 Digenea, 8 Nematoda, 4 Hirudinea, 3 Monogenea and 2 Myxozoa) in 21 fish host species from Guandu River, were listed in the current study, including 36 new locality records and 36 new host records. Also, a host-parasite list is included herein.

Four New Species of Ligophorus (Monogenea: Dactylogyridae) Parasitic on Mugil liza (Actinopterygii: Mugilidae) from Guandu River, Southeastern Brazil

Abstract Four species of Ligophorus (Monogenea: Dactylogyridae), i.e., L. tainhae n. sp., L. brasiliensis n. sp., L. guanduensis n. sp., and L. lizae n. sp., are described. The specimens were collected from the gills of Mugil liza (Mugilidae) from the Guandu River (22°48′32″S, 43°37′35″W), State of Rio de Janeiro, Brazil, between January 2008 and March 2008. The male copulatory organ of L. tainhae n. sp. differs from the all known species of this genus in having the largest accessory piece, the length of accessory piece exceeding the length of the copulatory organ tube, and the distal tip of the lower lobe crossing the upper lobe. Ligophorus brasiliensis n. sp. and L. guanduensis n. sp. have a similar shape of the accessory piece, but in L. guanduensis n. sp. the lower lobe is larger than the upper lobe (as opposed to L. brasiliensis n. sp.), the ratio between length of upper lobe and the length of the proximal part of the accessory piece before the bifurcation is shorter and the distal tip of the lower lobe extends to the level of the upper lobe (in L. brasiliensis n. sp. the distal tip of lower lobe crossing the upper lobe). In L. lizae n. sp., the terminal bifurcations of the accessory piece are equal in length and unequal in the other 3 new species. Species of Ligophorus are recorded for the first time from Brazil.

The patterns of organisation and structure of interactions in a fish-parasite network of a neotropical river.

The use of the complex network approach to study host-parasite interactions has helped to improve the understanding of the structure and dynamics of ecological communities. In this study, this network approach is applied to evaluate the patterns of organisation and structure of interactions in a fish-parasite network of a neotropical Atlantic Forest river. The network includes 20 fish species and 73 metazoan parasite species collected from the Guandu River, Rio de Janeiro State, Brazil. According to the usual measures in studies of networks, the organisation of the network was evaluated using measures of host susceptibility, parasite dependence, interaction asymmetry, species strength and complementary specialisation of each species as well as the network. The network structure was evaluated using connectance, nestedness and modularity measures. Host susceptibility typically presented low values, whereas parasite dependence was high. The asymmetry and species strength were correlated with host taxonomy but not with parasite taxonomy. Differences among parasite taxonomic groups in the complementary specialisation of each species on hosts were also observed. However, the complementary specialisation and species strength values were not correlated. The network had a high complementary specialisation, low connectance and nestedness, and high modularity, thus indicating variability in the roles of species in the network organisation and the expected presence of many specialist species.

Contracaecum sp. parasitizing Acestrorhynchus lacustris as a bioindicator for metal pollution in the Batalha River, southeast Brazil.

Pollution in aquatic ecosystems due to negative human activities remains a problem in both freshwater and marine environments and is an ongoing subject of research. Several studies have shown that some fish parasites can be used as a tool for biomonitoring because they demonstrate higher metal accumulation capacity compared to their host tissues. However, compared to acanthocephalans, information regarding the absorption mechanisms and accumulation rates in nematodes is relatively limited. Here, we evaluated the potential of larvae Contracaecum sp. (L3) as indicators of contamination by metals by analyzing thirteen element concentrations: magnesium (Mg), aluminum (Al), titanium (Ti), chromium (Cr), manganese (Mn), iron (Fe), nickel (Ni), copper (Cu), zinc (Zn), arsenic (As), cadmium (Cd), barium (Ba), and lead (Pb) in the parasites and host Acestrorhynchus lacustris, using inductively coupled plasma mass spectrometry. Twelve of the thirteen analyzed elements were detected in at least 2-fold higher concentrations (e.g. Ni) and were up to approximately 50-fold higher (e.g. Pb) in parasites than in host tissues, including elements known for their high toxicity (As, Cd, Pb) and those considered to be essential (Cu and Zn). Our results suggest that Contracaecum sp. larvae can be used as bioindicators of metal contamination because even in early stages of development, numerous essential and non-essential elements were accumulated, making this system a useful tool for monitoring polluted environments.

Myxobolus imparfinis n. sp. (Myxozoa: Myxosporea), a new gill parasite of Imparfinis mirini Haseman (Siluriformes: Heptapteridae) in Brazil

A new species of myxozoan, Myxobolus imparfinis n. sp. is described based on material from the gills of Imparfinis mirini (Haseman) (Heptapteridae). Mature myxospores are round, measuring 7.1–8.4 (7.9 ± 0.3) μm in length, 4.5–6.2 (5.5 ± 0.5) μm in width and 3.1–4.2 (3.7 ± 0.3) μm in thickness. The polar capsules are of unequal size, the larger polar capsule measuring 3.4–4.5 (3.9 ± 0.3) μm in length and 1.4–2.0 (1.7 ± 0.1) μm in width and the smaller capsule measuring 3.1–3.8 (3.4 ± 0.2) μm in length and 1.2–1.8 (1.5 ± 0.2) μm in width. The polar filament presents 6–7 coils. Spores had a prevalence of infection of 75% (6/8). In histological analyses we detected the development site of spores in primary filaments, in afferent branchial artery, thus classifying the type of infection to the filamental type and vascular subtype. The phylogenetic analyses of a dataset including species Myxobolus Bütschli, 1882 and Henneguya Thélohan, 1892 from South America recovered M. imparfinis n. sp. as a sister species of Myxobolus flavus Carriero, Adriano, Silva, Ceccarelli & Maia, 2013. To our knowledge, this is the first record of a myxozoan species parasitising I. mirini.

Community ecology of metazoan parasites of the sairú Cyphocharax nagelii from the Peixe River

A total of 57 sairus (Cyphocharax nagelii) from the Peixe River, state of São Paulo, southeastern Brazil, were examined between April 2011 and February 2012. Eleven species of metazoan parasites were collected and identified: Palombitrema triangulum, Curvianchoratus hexacleidus, Curvianchoratus singularis, Sphincterodiplostomum musculosum, Contracaecum sp., Cacatuocotyle paranaensis, Cosmoxynemoides aguirrei, Amplexibranchius bryconis, Brasergasilus sp., Ergasilus sp. and Clinostomum sp. The monogenean P. triangulum was the most prevalent species (61.40%) with the highest mean intensity (4.88). The monogeneans C. hexacleidus and C. singularis, the digenean S. musculosum and the nematode Contracaecum sp. also showed high prevalence. Only S. musculosum presented significant correlation between the total body weight of the host and its abundance. The parasitic infracommunities had a mean Brillouin diversity (HB) of 1.165 ± 0.987 and the maximum diversity was 1.671. The sex and length of the hosts did not influence the abundance of any parasite species. The community of metazoans in C. nagelii from the Peixe River was characterized by high richness and low uniformity.

A new species of Wallinia Pearse, 1920 (Digenea: Allocreadiidae) collected from Astyanax fasciatus (Cuvier, 1819) and A. lacustris Lucena and Soares, 2016 (Characiformes: Characidae) in Brazil based on morphology and DNA sequences

Wallinia brasiliensis n. sp. is described from the intestine of two species of tetras—Astyanax fasciatus (Cuvier, 1819) and Astyanax lacustris Lucena and Soares, 2016—collected from the Batalha River in São Paulo State, Brazil. The new species can be clearly distinguished from the other three congeneric species by its vitelline follicles extending from the genital pore to the end of the caeca, eggs lacking operculum, a larger egg size with a consequently lower number relative to the other three species, and the ovary located opposite the anterior testis. The validity of the new species was confirmed through a phylogenetic analysis of the 28S rRNA gene which showed that the new species is the sister taxon to Wallinia mexicana Pérez-Ponce de León, Razo-Mendivil, Mendoza-Garfía, Rubio-Godoy and Choudhury, 2015, a species infecting Astyanax mexicanus (De Filippi, 1853) in Mexico.

Parasitic communities of Hoplosternum littorale (Hancock, 1828) as indicators of environmental impact

The parasites are indicative of several biological aspects of their hosts, including their diet, migration, recruitment and phylogeny, but they can also be direct indicators of the environmental quality. Hoplosternum littorale is a fish that has a high commercial value in some South American countries. The fishes were collected from January to July 2012, in two locations of the Peixe River in the municipality of Anhembi, State of São Paulo, Brazil, which had different environmental and limnological characteristics (river mouth and Lagoa Cabeça de Boi). An amount of 30 fish specimens were captured in each location for the analysis of their parasitic fauna. Nine species of metazoan parasites were collected. Both Brillouin`s diversity index and Margalef`s richness index were greater in the Lagoa Cabeça de Boi. The ratio of heteroxenous and monoxenous parasite species richness (SH/SM) was higher in the Lagoa Cabeça de Boi. The results of the physicochemical analysis of the water showed that the mouth of the Peixe River can be considered an area that suffers more from anthropogenic actions than the Lagoa da Cabeça de Boi. Proteocephalus sp., Gyrodactylus sp., Scleroductus sp. and Capillaria (Neocapillaria) pterophylli are being registered for the first time in this host.