A checklist of species of the family Zoothamniidae (Ciliophora: Peritrichia), symbionts of crustaceans.

Eight genera are included in the family Zoothamniidae, and at the present the data of the epibiotic species on crustaceans is not updated. Thus, the main goal of the present work is to provide the checklist of zoothamniids worldwide reported as associated to several groups of crustaceans, including some data of their geographic distribution, and also to provide the complete list of species of this peritrich group. We obtained all available data of family Zoothamniidae and checked their taxonomic status. Then we provided the complete list of species including those reported as epibionts on crustacean hosts. We obtained 156 species included in eight genera of Zoothamniidae, being 85 species recorded as symbionts on 86 species of hosts. Genus Zoothamnium contained the higher number (56) of epibiotic species on crustaceans, and genus Pseudohaplocaulus has not been reported for any crustacean. The reviewed data highlights the concentration of records in Europe, and stands out the need to amplify sampling and studies in the Southern Hemisphere. The main groups of crustaceans infested by zoothamniids are the amphipods, isopods and decapods.

Incorporating mitogenome sequencing into integrative taxonomy: The multidisciplinary redescription of the ciliate Thuricola similis (Peritrichia, Vaginicolidae) provides new insights into the evolutionary relationships among Oligohymenophorea subclasses.

The evolutionary relationships among Oligohymenophorea subclasses are under debate as the phylogenomic analysis using a large dataset of nuclear coding genes is significantly different to the 18S rDNA phylogeny, and it is unfortunately not stable within and across different published studies. In addition to nuclear genes, the faster-evolving mitochondrial genes have also shown the ability to solve phylogenetic problems in many ciliated taxa. However, due to the paucity of mitochondrial data, the corresponding work is scarce, let alone the phylogenomic analysis based on mitochondrial gene dataset. In this work, we presented the characterization on Thuricola similis Bock, 1963, a loricate peritrich (Oligohymenophorea), incorporating mitogenome sequencing into integrative taxonomy. As the first mitogenome for the subclass Peritrichia, it is linear, 38,802 bp long, and contains two rRNAs, 12 tRNAs, and 43 open reading frames (ORFs). As a peculiarity, it includes a central repeated region composed of tandemly repeated A-T rich units working as a bi-transcriptional start. Moreover, taking this opportunity, the phylogenomic analyses based on a set of mitochondrial genes were also performed, revealing that T. similis, as a representative of Peritrichia subclass, branches basally to other three Oligohymenophorea subclasses, namely Hymenostomatia, Peniculia, and Scuticociliatia. Evolutionary relationships among those Oligohymenophorea subclasses were discussed, also in the light of recent phylogenomic reconstructions based on a set of nuclear genes. Besides, as a little-known species, T. similis was also redescribed and neotypified based on data from two populations collected from wastewater treatment plants (WWTPs) in Brazil and Italy, by means of integrative methods (i.e., living observation, silver staining methods, scanning and transmission electron microscopy, and 18S rDNA phylogeny). After emended diagnosis, it is characterized by: (1) the sewage habitat; (2) the lorica with a single valve and small undulations; (3) the 7-22 µm-long inner stalk; and (4) the presence of only a single postciliary microtubule on the left side of the aciliferous row in the haplokinety. Among Vaginicolidae family, our 18S rRNA gene-based phylogenetic analysis revealed that Thuricola and Cothurnia are monophyletic genera, and Vaginicola could be a polyphyletic genus.

Trichodina modesta: an exotic ciliate in the Neotropical region parasitizing an unusual host.

In this study, an important ornamental fish, Betta splendens (Osphronemidae), from three different Brazilian states was examined for parasitic infestations. Smears with parasites were impregnated with silver nitrate or stained using Giemsa for taxonomic evaluation. A disc-shaped trichodinid with a body diameter of 39.7 ± 3.3 µm, adhesive disc diameter of 32.9 ± 3.1 µm and denticulate ring diameter of 19.5 ± 2.0 µm was found. The morphological characteristics resembled those of Trichodina modesta Lom, 1970, a species that shows clear host specificity for Cypriniformes. Until now, its occurrence was restricted to the Eurasian region. In the present study, a new host for T. modesta is reported and therefore the first occurrence of this species in the Americas. The parasite was possibly introduced into the Neotropical region through the exotic fish trade, especially of Cypriniformes used by aquarists. The distribution of this ciliate is discussed and a checklist of localities and hosts for the species is provided.

Trichodina modesta: an exotic ciliate in the Neotropical region parasitizing an unusual host / Trichodina modesta: exótico ciliado na região Neotropical parasitando hospedeiro não usual

In this study, an important ornamental fish, Betta splendens (Osphronemidae), from three different Brazilian states was examined for parasitic infestations. Smears with parasites were impregnated with silver nitrate or stained using Giemsa for taxonomic evaluation. A disc-shaped trichodinid with a body diameter of 39.7 ± 3.3 µm, adhesive disc diameter of 32.9 ± 3.1 µm and denticulate ring diameter of 19.5 ± 2.0 µm was found. The morphological characteristics resembled those of Trichodina modesta Lom, 1970, a species that shows clear host specificity for Cypriniformes. Until now, its occurrence was restricted to the Eurasian region. In the present study, a new host for T. modesta is reported and therefore the first occurrence of this species in the Americas. The parasite was possibly introduced into the Neotropical region through the exotic fish trade, especially of Cypriniformes used by aquarists. The distribution of this ciliate is discussed and a checklist of localities and hosts for the species is provided.

Neste estudo, o peixe ornamental Betta splendens (Osphronemidae) foi examinado a partir de três diferentes Estados brasileiros para infestações parasitárias. Esfregaços contendo parasitos foram impregnados com nitrato de prata ou corados com Giemsa para avaliação taxonômica. Foi observado o tricodinídeo em forma de disco com 39,7 ± 3,3 µm de diâmetro do corpo, disco adesivo com 32,9 ± 3,1 µm e anel denticulado 19,5 ± 2,0 µm de diâmetro. As características morfológicas foram semelhantes à Trichodina modesta Lom, 1970, uma espécie que apresenta especificidade de hospedeiro por peixes Cypriniformes com ocorrência na Região Euro-asiática. No presente estudo, um novo hospedeiro para T. modesta é reportado, assim como a primeira ocorrência da espécie na América. O parasito tem sido possivelmente introduzido na região Neotropical com o comércio de peixes exóticos, principalmente Cypriniformes usados por aquariofilistas. A dispersão do ciliado é discutida e um “checklist” de localidades e hospedeiros apresentado.