Roberto Júnio Pedroso Dias

The influence of environmental characteristics on the distribution of ciliates (Protozoa, Ciliophora) in an urban stream of southeast Brazil

The aim of this research was to study the ciliated protozoa community at three sampling stations that receive different levels of domestic sewage along the São Pedro Stream in the municipality of Juiz de Fora, Minas Gerais, Brazil, in order to determine the influence of organic pollution on this community and to assess the feasibility of using ciliates as water quality indicators. Four physical-chemical parameters of the water samples were evaluated: dissolved oxygen concentration, electrical conductivity, pH and temperature. The sediment was obtained manually, using dredges with capacity of 300 mL, at each collection point. Point 1 was located in a rural region that receives a low sewage load, while Points 2 and 3 were located in populated regions receiving high sewage loads. We found 22 ciliate species, of which 18 are included in the saprobic system and are considered bioindicators. These showed beta-mesosaprobic environments at Point 1 and alfa-mesosaprobic to polisaprobic environments at Points 2 and 3. The low levels of dissolved oxygen and the high electrical conductivity values at Points 2 and 3, together with the strong similarity between the ciliate taxocenoses of these points and the weak similarity between Point 1 and the other two, confirm the high sewage loads received at the latter two points. The combination of the biological indicators and physical-chemical analyses therefore proved itself to be an efficient method of evaluating water quality, and has excellent potential to support decisions on the conservation of headwaters and recuperation of degraded environments in lotic systems.

Redescription of Licnophora chattoni Villeneuve-Brachon, 1939 (Ciliophora, Spirotrichea), associated with Zyzzyzus warreni Calder, 1988 (Cnidaria, Hydrozoa)

Licnophora chattoni, found in association with Zyzzyzus warreni, a tubulariid hydroid epizoic in sponges from São Sebastião (SP, Brazil), is redescribed and illustrated using light and electron microscopy. The ciliate has a flexible, transparent body formed by an oval anterior region linked to the posterior basal disc via a flexible neck region. Numerous cortical granules are observed scattered throughout the body and densely packed along the neck. The adoral zone is formed by about 81 external and 24 infundibular paramembranelles. The paroral membrane, formed by a row of long cilia arranged in monokinetids, extends through a groove in the body to the adhesive disc. Two dorsal kinetids are present along the right body margin and around the neck. The adhesive disc (18μm in diameter) lacks cilia in the area above the velum. The velum covers a row of dikinetids bearing long cilia and four dikineties, two or three of which are interrupted on the ventral surface. Nine to twelve macronuclear nodules connected by isthmuses are distributed in the cytoplasm, plus two nodules located in the adhesive disc and between those there is an ovate micronucleus.

News records of phoresy and hyperphoresy among treefrogs, ostracods, and ciliates in bromeliad of Atlantic forest

The bromeliad habitat contributes to a high biodiversity and we recorded three treefrog species as new phoretic agents of ostracods, and a first case of hyperphoresy among treefrogs, ostracods and ciliates, in these habitats of Atlantic Forest. Densities of ciliates and ostracods showed significant relationships suggesting the importance of hyperphoresy for ciliate dispersion.

Spatial and temporal occurrence of Rhabdostyla cf. chironomi Kahl, 1933 (Ciliophora, Peritrichia) as an epibiont on chironomid larvae in a lotic system in the neotropics

In order to show how environmental factors could influence the spatial and temporal distribution of epibiosis, we investigated the occurrence of the ciliate Rhabdostyla cf. chironomi (Ciliophora, Peritrichia) attached to Chironomidae larvae in an urban stream in southeast Brazil. Samples were collected monthly for 1-year period at five sampling stations along the stream. Among the 24 genera analyzed, the genus Chironomus was the most abundant, with 16.84% carrying R. cf. chironomi. This epibiotic relationship was only recorded in sample stations located in a heavily populated urban area of the stream. Statistical analyses demonstrated significant correlations between infestation prevalence and environmental parameters such as rainfall, bacterial density, and host abundance. The occurrence of epibionts on the larvae was spatially and temporally heterogeneous. The results are discussed in terms of possible factors related to the heterogeneous spatial and temporal occurrence. Greater understanding of the ecological factors governing the occurrence of the epibiont–host relationship is essential to establish future use of this relationship as water quality indicator in lotic systems.

Morphology and 18S rDNA gene sequence of Blepharisma sinuosum Sawaya, 1940 (Ciliophora: Heterotrichea) from Brazil

The morphology and morphometric data of seven populations of Blepharisma sinuosum from southeastern Brazil were investigated. The description is based on live observations, protargol impregnation, and scanning electron microscopy. Blepharisma sinuosum measures 75-255μm in length and 25-93μm in width and has a spindle-shaped body, pink color, a single contractile vacuole located at the posterior end, 50 adoral membranelles, a conspicuous paroral, 17-35 somatic kineties, a moniliform macronucleus with 2-7 connected nodules, and 3-20 micronuclei. Morphological comparisons with similar species were performed and suggest that B. americanum is the junior synonym of B. sinuosum. The 18S rDNA gene sequence of B. sinuosum was obtained and compared with that of other Blepharisma species. The length and GC content of the obtained sequence is 1652bp and 47.03%, respectively, and has a very high structural similarity (99.9%) with the B. undulans sequence. The validity of the classification of Blepharisma species in morphonuclear subgenera is also discussed.

Quantitative study of Trichodina heterodentata (Ciliophora: Mobilia) infrapopulations infesting tadpoles of a Brazilian endemic toad Rhinella pombali (Anura: Bufonidae)

In this work we investigated the quantitative aspects of the relationship between Rhinella pombali (Baldissera, Caramaschi & Haddad, 2004) tadpoles and their trichodinid ectoparasites. Specimens were collected from a small stream located at an agricultural area between rainforest fragments in southeastern Brazil. A total of 80 tadpoles were investigated. Trichodina heterodentata Duncan, 1977 was the only trichodinid ciliate species recovered. All tadpoles were naturally infested by T. heterodentata with a mean intensity of 695.14 ± 33.33 trichodinid ciliates per tadpole. A positive correlation was observed between the intensity of the infestation and tadpole weight. Intensity of infestation did not significantly influence mean trichodinid diameter in the populations studied. This is the first study investigating density-dependent effects in interspecific interactions between trichodinids and anurans.

Protozoan ciliate epibionts on the freshwater apple snail Pomacea figulina (Spix, 1827) (Gastropoda, Ampullariidae) in an urban stream of south‐east Brazil

The objective of this study was to record and analyze the prevalence of ciliated protozoa associated with prosobranchian snails of the species Pomacea figulina collected from an urban stream in south‐eastern Brazil. Four collections were carried out between December, 2005, and March, 2006, from which 23 snails and 10 ‘empty’ shells were obtained. The shells and opercula were scraped over Petri dishes and the ciliates were observed using bright field and phase contrast microscopy. Seven species of ciliates were recorded on the snails of P. figulina. Of the 23 snails analyzed, 82.60% (n = 19) were infested with at least one species of ciliate. No ciliates were found on the ‘empty’ shells and opercula. The results are discussed in terms of ecological aspects involved in this association.

First record of epibionts peritrichids and suctorians (Protozoa, Ciliophora) on Pomacea lineata (Spix, 1827)

This study made a survey on the ciliate protozoans from Peritrichid and Suctorian taxa, epibionts of Pomacea lineata (Spix, 1827) (Ampullariidae). Fifty mollusks were collected in places of irrigation ditches and shell was scraped with a scalpel and the extracted material was analyzed in vivo by light microscopy. All examined mollusks presented epibiont ciliates on their shells. For the first time epibiont ciliates in P. lineata was record. Seven genera of ciliates: five peritrichids and two suctorians, were identified and classified within the subclass Peritrichia: Carchesium Ehrenberg, 1838 (Vorticellidae), Epistylis Ehrenberg, 1830 (Epistylidae), Opercularia Stein, 1854 (Operculariidae), Vaginicola Lamarck, 1816 (Vaginicolidae) and Vorticella Linnaeus, 1767 (Vorticellidae); and Suctoria: Acineta Ehrenberg,1834 (Acinetidae) and Tokophrya Butschli,1889 (Tokophrydae). The results showed that P. lineata constitute the microenvironment of a ciliate protozoan community that presents complex trophic interactions.

Redescription and Phylogenetic Position of Condylostoma arenarium Spiegel, 1926 (Ciliophora, Heterotrichea) from Guanabara Bay, Brazil

Details on Condylostoma arenarium infraciliature have not been described; therefore, it is considered a poorly known species. The lack of detailed description on C. arenarium morphology caused several misidentifications that have accumulated in the literature. In this study, we present the first complete description of C. arenarium infraciliature based on protargol‐impregnated organisms and scanning electron microscopy. We also have inferred the phylogenetic position of this species based on 18S rRNA sequences. The main characteristics of C. arenarium population from Guanabara Bay are as follows: in vivo elongated body shape with 350–600 μm length × 70–220 μm width, they are highly contractile when subjected to disturbances, green‐yellowish cortical granules are present, contractile vacuoles absent, V‐shaped peristome comprises approximately 1/5 of the total length, adoral zone with 83–145 membranelles, 1–2 small frontal cirrus observed only in impregnated specimens, 10–15 fiber‐like stripes arranged transversely on the inner wall of the oral cavity, 30–45 somatic kineties, moniliform macronucleus with 15–20 nodules. Some observations on morphogenesis of C. arenarium were also included. In phylogenetic analyses, C. arenarium clustered with Condylostoma sp. within a clade composed of three C. curva sequences with high support values.

Feeding behavior of Frontonia leucas (Ehrenberg) (Protozoa, Ciliophora, Hymenostomatida) under different environmental conditions in a lotic system

The objective of this study was to record and describe the morphological changes and the ingestion mechanisms of Frontonia leucas (Ehrenberg, 1833) according to the food type and to relate the food ingested with the different environmental conditions in a lotic system, namely Sao Pedro stream, located in the municipality of Juiz de Fora, Minas Gerais, Brazil. We sampled three points on a monthly basis from August 2002 to June 2003, each of which receiving different levels of untreated sewage. We prepared culture media for the ciliate specimens containing filtered water from each point and the types of food observed inside F. leucas (cyanobacteria, diatoms, desmids and testate amoebas). We observed the ingestion mechanisms of F. leucas in vivo, under a phase contrast optical microscope, using instantaneous sampling and sequence sampling as behavior observation methods, noting the following parameters: dissolved oxygen concentration, pH, conductivity and water temperature. We noted the F. leucas ciliates ingesting diatoms and desmids at collection point 1 and filamentous cyanobacteria, testate amoebas (Arcella and Centropyxis) and rotifers at points 2 and 3. The present work records for the first time the ingestion of testate amoebas of the genus Centropyxis by F. leucas. We noted five ingestion mechanisms by F. leucas while feeding on cyanobacteria and testate amoebas of the genus Centropyxis, three of these related to the ciliary action and two involving physical changes in the cytoplasm. For ingestion of diatoms, desmid (Closterium) and Arcella, the mechanisms involving ciliary action alone were sufficient for ingestion, since these preys are smaller than the ciliate under study. The autecological data registered for F. leucas were 1.98-8.01 mg l-1 O2, pH 6.9-8.73, 58-390 µS/cm and 19.5-26.2oC, confirming its ample ecological valence.