Oral Apparatus Research Articles

Omnidens appendages and the origin of radiodont mouthparts

AbstractThe sophisticated, modular and adaptable body plan of arthropods underpins their dominance in marine invertebrate communities. The origin of this body plan from legged lobopodian worms can be inferred from Cambrian Konservat‐Lagerstätten, but our understanding retains some notable gaps: not least in the transition from swimming lobopodians such as Kerygmachela and Pambdelurion to robustly sclerotized radiodonts such as Anomalocaris. A large Pambdelurion‐like fossil from the Xiaoshiba biota, Omnidens qiongqii sp. nov., exhibits a novel combination of characters: an oral apparatus with a non‐radial configuration; and centimetric talon‐like grasping structures with heavily sclerotized blade‐like spines. The novel morphology broadens the interpretative framework for associated Cambrian taxa, demonstrating continuity in the morphology of euarthropod appendages prior to the origin of podomeres. A reappraisal of the euarthropod stem lineage suggests that radially arranged mouthparts may be a radiodont novelty, rather than an inheritance from the ancestral ecdysozoan. These results further resolve the evolutionary origins of the euarthropod body plan.

The three-dimensionally articulated oral apparatus of a Devonian heterostracan sheds light on feeding in Palaeozoic jawless fishes.

Attempts to explain the origin and diversification of vertebrates have commonly invoked the evolution of feeding ecology, contrasting the passive suspension feeding of invertebrate chordates and larval lampreys with active predation in living jawed vertebrates. Of the extinct jawless vertebrates that phylogenetically intercalate these living groups, the feeding apparatus is well-preserved only in the early diverging stem-gnathostome heterostracans. However, its anatomy remains poorly understood. Here, we use X-ray microtomography to characterize the feeding apparatus of the pteraspid heterostracan Rhinopteraspis dunensis (Roemer, 1855). The apparatus is composed of 13 plates arranged approximately bilaterally, most of which articulate from the postoral plate. Our reconstruction shows that the oral plates were capable of rotating around the transverse axis, but likely with limited movement. It also suggests the nasohypophyseal organs opened internally, into the pharynx. The functional morphology of the apparatus in Rhinopteraspis precludes all proposed interpretations of feeding except for suspension/deposit feeding and we interpret the apparatus as having served primarily to moderate the oral gape. This is consistent with evidence that at least some early jawless gnathostomes were suspension feeders and runs contrary to macroecological scenarios that envisage early vertebrate evolution as characterized by a directional trend towards increasingly active food acquisition.

How do different concentrations of aluminum and zinc affect the survival, body size, morphology and immune system of Physalaemus cuvieri (Fitzinger, 1826) tadpole?

ABSTRACT The assessment of amphibian responses as bioindicators of exposure to chemical pollutants is an important tool for conservation of native species. This study aimed to investigate the effects of chronic aluminum (Al) and zinc (Zn) exposure on survival, body size, morphology (malformations), and immune system (leukocyte profile) in P. cuvieri tadpoles. Ecotoxicological analyses were performed utilizing chronic toxicity tests in which 210 tadpoles at the 25th Gosner developmental stage were exposed to Al and Zn. Individuals of P. cuvieri were maintained in glass containers containing various concentrations of aluminum sulfate (0.1, 0.2, or 0.3 mg/L) and zinc sulfate (0.18, 0.27 or 0.35 mg/L), and tests were performed in triplicate. After 14 days, amphibians were weighed, measured and survival rate, malformations in the oral and intestine apparatus, leukocyte profile, and ratio between neutrophils and lymphocytes determined. The differing concentrations of Al and Zn did not produce lethality in P. cuvieri where 95% of the animals survived 326 hr following metal exposure. Individuals exposed to Zn achieved greater body growth and weight gain compared to controls. Aluminum increased weight gain compared controls. These metals also produced malformations of the oral and intestine apparatus and enhanced occurrence of hemorrhages, especially at the highest doses. Lymphocytes were the predominant cells among leukocytes, with lymphopenia and neutrophilia observed following Al and Zn treatment, as evidenced by elevated neutrophil/lymphocyte ratio, an important indicator of stress in animals. Data suggest that further studies need to be carried out, even with metal concentrations higher than those prescribed by CONAMA, to ensure the conservation of this species.

Setal morphology of oral apparatus of Aegla longirostri Bond-Buckup & Buckup, 1994 (Decapoda: Aeglidae).

The seta, a type of projection of the cuticle in crustaceans, has essential mechanical and sensory functions. Due to the diversity of their morphology and distribution patterns on the articles of different appendages, setae can be helpful as taxonomic characters. To assist future studies on the potential use of setae as a diagnostic character in aeglids, we used scanning electron microscopy to analyze the morphology of setae from the oral apparatus of Aegla longirostri Bond-Buckup & Buckup, 1994, and compared our data to the literature. We identified nine setal types (simple, serrate, stout serrate, sword, plumose, pappose, comb, serrulate, and cuspidate), of which the last two had not been previously described in adult aeglids. Our results are a first step towards future comparisons of setal morphology in the genus Aegla, which includes cryptic species complexes, to ascertain the usefulness of setae as a character to aid in the description of species of this group, which has a conserved general morphology.

Land use around influences the entomological community in lettuce horticultural systems.

The complexity of the agroecosystem can also be assessed by the different land uses in the system and the surroundings, being a relevant way to assess the heterogeneity of the landscape and the effects on the community of interest, in this case, entomofauna. Thus, the objective of this work is to verify how the use of soil in the surroundings of Chilean lettuce horticultural systems, in the Coquimbo Region, alters the entomological community of the crop. Insect sampling was conducted (February 2021 to March 2022) using yellow pan traps. Two sites will be sampled on each of the seven studied lettuce crops. Land use and land cover classes were defined: Forests, water bodies, shrub vegetation, grasslands, barren lands, impermeable surfaces, and urban areas. After land use and land cover classification, buffers of 500 to 5,000 m were created around each data collection point. For data analysis, the percentages of land use of different classes were compared with the ecological attributes: Abundance of insects, abundance of insect pests, richness of entomological families and types of oral apparatus (licker-sucker, mandible, picker-sucker, and sucker). Land uses at different distances from horticultural systems affected the entomological community.

Global and local functions of the Fused kinase ortholog CdaH in intracellular patterning in Tetrahymena.

Ciliates assemble numerous microtubular structures into complex cortical patterns. During ciliate division, the pattern is duplicated by intracellular segmentation that produces a tandem of daughter cells. In Tetrahymena thermophila, the induction and positioning of the division boundary involves two mutually antagonistic factors: posterior CdaA (cyclin E) and anterior CdaI (Hippo kinase). Here, we characterized the related cdaH-1 allele, which confers a pleiotropic patterning phenotype including an absence of the division boundary and an anterior-posterior mispositioning of the new oral apparatus. CdaH is a Fused or Stk36 kinase ortholog that localizes to multiple sites that correlate with the effects of its loss, including the division boundary and the new oral apparatus. CdaH acts downstream of CdaA to induce the division boundary and drives asymmetric cytokinesis at the tip of the posterior daughter. CdaH both maintains the anterior-posterior position of the new oral apparatus and interacts with CdaI to pattern ciliary rows within the oral apparatus. Thus, CdaH acts at multiple scales, from induction and positioning of structures on the cell-wide polarity axis to local organelle-level patterning.

LABIO-ALVEOLAR MOULDING FOR ESTHETIC AND FUNCTIONAL REHABILITATION OF OROPHARYNGEAL TERATOMA INDUCED SKELTAL AND SOFT TISSUE DEFORMITY IN NEWBORN - A CASE REPORT

Teratomaare true neoplasms composed of tissue derived from all the three germinal layers.Teratomas arising in the palate pharynx or tongue and protrude from the mouth can result in life-threatening airway obstruction and feeding difficulties.Surgical excision improves the chance of survival of the newborn but it results in deformation of oral and masticatory apparatus. This article discusses about the role of pediatric dentist in reestablishing the form and function of the facial apparatus following surgical excision of intraoral teratoma.

Effects of six pyrimidine analogs on the growth of Tetrahymena thermophila and their implications in pyrimidine metabolism.

Tetrahymena are ciliated protists that have been used to study the effects of toxic chemicals, including anticancer drugs. In this study, we tested the inhibitory effects of six pyrimidine analogs (5-fluorouracil, floxuridine, 5'-deoxy-5-fluorouridine, 5-fluorouridine, gemcitabine, and cytarabine) on wild-type CU428 and conditional mutant NP1 Tetrahymena thermophila at room temperature and the restrictive temperature (37°C) where NP1 does not form the oral apparatus. We found that phagocytosis was not required for pyrimidine analog entry and that all tested pyrimidine analogs inhibited growth except for cytarabine. IC50 values did not significantly differ between CU428 and NP1 for the same analog at either room temperature or 37°C. To investigate the mechanism of inhibition, we used two pyrimidine bases (uracil and thymine) and three nucleosides (uridine, thymidine, and 5-methyluridine) to determine whether the inhibitory effects from the pyrimidine analogs were reversible. We found that the inhibitory effects from 5-fluorouracil could be reversed by uracil and thymine, from floxuridine could be reversed by thymidine, and from 5'-deoxy-5-fluorouridine could be reversed by uracil. None of the tested nucleobases or nucleosides could reverse the inhibitory effects of gemcitabine or 5-fluorouridine. Our results suggest that the five pyrimidine analogs act on different sites to inhibit T. thermophila growth and that nucleobases and nucleosides are metabolized differently in Tetrahymena.

Captive breeding, embryonic and larval development of Ranitomeyavariabilis (Zimmermann & Zimmermann, 1988), (Anura, Dendrobatidae).

A solid basis to address the conservation challenges of amphibians requires an increased knowledge on their natural history and biology. Recent data on reproductive modes in amphibians suggest that they are much more complex and variable than previously thought but understudied. However, detailed information on the reproductive history is especially important to fill the current knowledge gaps. Following recent taxonomic changes in Ranitomeyavariabilis, information about captive-breeding management, image-based measurements of total length and surface area of the silhouette for individuals from embryonic to metamorphic development, and detailed larval staging for captive-bred specimens are provided from French Guiana. The development of R.variabilis from the stage eight (Gosner 1960) through metamorphosis took 79 to 91 days (n = 6) with a survival rate of 46%. The developmental stages largely matched those of the generalized staging system of Gosner (1960), with differences in the stages when labia and teeth differentiation and atrophy of the oral apparatus occurred. Compared with other studies the total length of R.variabilis tadpoles was greater at given stages than those of R.variabilis from a Peruvian population and those of the sister species, R.amazonica. Other studies concerning growth curves based on surface area data revealed that R.variabilis tadpoles at peak size were larger than those of R.amazonica, R.imitator, R.reticulata, R.sirensis, and R.vanzolinii, but smaller than R.benedicta. Our results represent the first embryonic and larval staging for R.variabilis, and detailed information is provided on their initial life phases. These data may facilitate the identification of R.variabilis tadpoles in the wild, as well helping to clarify the biogeographical distribution and taxonomic arrangement of the species. In addition, knowledge is added to the captive-breeding methodology for the species.

The search finds an end: the morphologically chimeric hysterocinetids belong to the subclass Hymenostomatia (Ciliophora: Oligohymenophorea)

Abstract The digestive tract of oligochaetes harbours a diverse ciliate community embracing plagiotomids, nyctotherids, astomes, and hysterocinetids. Although several hundred intestinal ciliate species are known, only two hysterocinetids have been reported from the intestine of Holarctic lumbricid earthworms hitherto. The present study is focused on the taxonomy, morphology, and molecular phylogeny of two lumbricid-dwelling taxa, the insufficiently known Protoptychostomum simplex and Hysterocineta bellerophon sp. nov., detected in Central Europe. Diagnoses of the genera Protoptychostomum and Hysterocineta were improved taking into account also features of the oral ciliature for the first time. In the past, the proper classification of hysterocinetids in the class Oligohymenophorea was hampered by the dramatic remodelling of the anterior body end into a thigmotactic sucker, as well as by the helicalization and transfer of the oral apparatus to the posterior body pole. The present phylogenetic analyses of nuclear and mitochondrial genes robustly reject the classification of hysterocinetids in subclass Scuticociliatia or as a distinct subclass, Hysterocinetia. However, hysterocinetids were consistently and robustly nested deep in subclass Hymenostomatia in a sister-position to the free-living Tetrahymena paravorax. The hymenostome affinity of hysterocinetids is also corroborated by the parakinetal stomatogenesis and the stichodyad paroral membrane accompanied by three regularly organized membranelles.

Polymorphism, gigantism, and cannibalism, one stylonychid ciliate (Ciliophora, Hypotricha) to rule them all.

The morphology, ontogenesis, and molecular phylogeny of the polymorphic and cannibalistic giant forming Tetmemena polymorpha n. sp., found in a brackish water sample in South Korea, were investigated. The present species has long been misidentified as "Oxytricha bifaria." The new investigation shows that the species produces three morphologically different morphs. The small morph is bacterivorous and characterized by its small body size and slim body and it is found only in the stationary and decline phases of the culture. The large morph has a wide body, larger oral apparatus, and feeds on small eukaryotes such as yeast cells and small ciliates. It divides very quickly and produces the other two morphs and found in the exponential phase of the cultures. The giant morph is characterized by its huge body and oral apparatus. It feeds on the small morph cells of the same species and other ciliates, and occurs together with the small morph. Phylogenetic analyses based on the 18S rRNA gene sequences show that the new species is placed in a sister subclade to that containing other Tetmemena sequences. Moreover, Tetmemena indica Bharti et al., 2019 nov. stat. is raised to species level based on the differences in the cyst morphology and the dorsal ciliature to the authoritative Tetmemena pustulata population.

The Tetrahymena bcd1 mutant implicates endosome trafficking in ciliate, cortical pattern formation.

Ciliates, such as Tetrahymena thermophila, evolved complex mechanisms to determine both the location and dimensions of cortical organelles such as the oral apparatus (OA: involved in phagocytosis) cytoproct (Cyp: for eliminating wastes) and contractile vacuole pores (CVPs: involved in water expulsion). Mutations have been recovered in Tetrahymena that affect both the localization of such organelles along anterior-posterior and circumferential body axes, and their dimensions. Here we describe BCD1, a ciliate pattern-gene that encodes a conserved beige-BEACH-domain containing protein a with possible PKA-anchoring activity. Similar proteins have been implicated in endosome trafficking, and are linked to human Chediak-Higashi syndrome and autism. Mutations in the BCD1 gene broaden cortical organelle domains as they assemble during pre-division development. The Bcd1 protein localizes to membrane pockets at the base of every cilium that are active in endocytosis. PKA activity has been shown to promote endocytosis in other organisms, so we blocked clathrin-mediated endocytosis (using 'dynasore') and inhibited PKA (using H89). In both cases, treatment produced partial phenocopies of the bcd1 pattern mutant. This study supports a model in which the dimensions of diverse cortical organelle assembly-platforms may be determined by regulated balance between constitutive exocytic delivery and PKA-regulated endocytic retrieval of organelle materials and determinants.

The transcriptional state and chromatin landscape of cichlid jaw shape variation across species and environments.

Adaptive phenotypes are shaped by a combination of genetic and environmental forces, but how they interact remains poorly understood. Here, we utilize the cichlid oral jaw apparatus to better understand these gene-by-environment effects. First, we employed RNA-seq in bony and ligamentous tissues important for jaw opening to identify differentially expressed genes between species and across foraging environments. We used two Lake Malawi species adapted to different foraging habitats along the pelagic-benthic ecomorphological axis. Our foraging treatments were designed to force animals to employ either suction or biting/scraping, which broadly mimic pelagic or benthic modes of feeding. We found a large number of differentially expressed genes between species, and while we identified relatively few differences between environments, species differences were far more pronounced when they were challenged with a pelagic versus benthic foraging mode. Expression data carried the signature of genetic assimilation, and implicated cell cycle regulation in shaping the jaw across species and environments. Next, we repeated the foraging experiment and performed ATAC-seq procedures on nuclei harvested from the same tissues. Cross-referencing results from both analyses revealed subsets of genes that were both differentially expressed and differentially accessible. This reduced dataset implicated notable candidate genes including the Hedgehog effector, KIAA0586 and the ETS transcription factor, etv4, which connects environmental stress and craniofacial morphogenesis. Taken together, these data provide novel insights into the epigenetic, genetic and cellular bases of species- and environment-specific bone shapes.

Cinetochilides minimus sp. nov., a Tiny Benthic Ciliate (Protozoa, Ciliophora) from Brackish Water in Korea

During a field survey of Korean marine and brackish water ciliate diversity, we collected a tiny benthic ciliate (13–18 µm long in vivo) from the opening of a brackish water lagoon (10‰). At low magnification, it resembles members of the genus Aspidisca because of the oval body shape and the benthic life style, but is not thigmotactic. Based on the observations of living cells, silver-impregnated specimens (i.e., using protargol, silver carbonate, and wet silver nitrate), SEM images, and the 18S rRNA gene sequences, we confirmed that it is a new member of the genus Cinetochilides. The new species, C. minimus sp. nov., can be easily distinguished from other congeners mainly by the fragmented somatic kinety 1. In spite of the small size, the new species has more than 200 basal bodies, including those in the oral apparatus. The arrangement of the ciliary pattern is rather confusing because of the polymerized kinetids, the sparse basal bodies, the non-ciliated area on the dorsal side, and the presence of parasomal sacs next to the kinetosomes. In the present study, we provide a detailed morphological description and infer the phylogenetic position of Cinetochilides minimus sp. nov. based on 18S rRNA gene sequences.

Modular, cascade-like transcriptional program of regeneration in Stentor.

The giant ciliate Stentor coeruleus is a classical model system for studying regeneration and morphogenesis in a single cell. The anterior of the cell is marked by an array of cilia, known as the oral apparatus, which can be induced to shed and regenerate in a series of reproducible morphological steps, previously shown to require transcription. If a cell is cut in half, each half regenerates an intact cell. We used RNA sequencing (RNAseq) to assay the dynamic changes in Stentor's transcriptome during regeneration, after both oral apparatus shedding and bisection, allowing us to identify distinct temporal waves of gene expression including kinases, RNA -binding proteins, centriole biogenesis factors, and orthologs of human ciliopathy genes. By comparing transcriptional profiles of different regeneration events, we identified distinct modules of gene expression corresponding to oral apparatus regeneration, posterior holdfast regeneration, and recovery after wounding. By measuring gene expression after blocking translation, we show that the sequential waves of gene expression involve a cascade mechanism in which later waves of expression are triggered by translation products of early-expressed genes. Among the early-expressed genes, we identified an E2F transcription factor and the RNA-binding protein Pumilio as potential regulators of regeneration based on the expression pattern of their predicted target genes. RNAi-mediated knockdown experiments indicate that Pumilio is required for regenerating oral structures of the correct size. E2F is involved in the completion of regeneration but is dispensable for earlier steps. This work allows us to classify regeneration genes into groups based on their potential role for regeneration in distinct cell regeneration paradigms, and provides insight into how a single cell can coordinate complex morphogenetic pathways to regenerate missing structures.

Purinergic Signaling in Oral Tissues.

The role of the purinergic signal has been extensively investigated in many tissues and related organs, including the central and peripheral nervous systems as well as the gastrointestinal, cardiovascular, respiratory, renal, and immune systems. Less attention has been paid to the influence of purines in the oral cavity, which is the first part of the digestive apparatus and also acts as the body’s first antimicrobial barrier. In this review, evidence is provided of the presence and possible physiological role of the purinergic system in the different structures forming the oral cavity including teeth, tongue, hard palate, and soft palate with their annexes such as taste buds, salivary glands, and nervous fibers innervating the oral structures. We also report findings on the involvement of the purinergic signal in pathological conditions affecting the oral apparatus such as Sjögren’s syndrome or following irradiation for the treatment of head and neck cancer, and the use of experimental drugs interfering with the purine system to improve bone healing after damage. Further investigations are required to translate the results obtained so far into the clinical setting in order to pave the way for a wider application of purine-based treatments in oral diseases.

Description of the life cycle of Dolops discoidalis (Branchiura: Argulidae), collected in Pseudoplatystoma punticfer raised in captivity in the Peruvian Amazon

Species of Branchiura have structures that undergo evolutionary modifications such as: oral suction apparatus and hook-shaped appendages, which are used for attachment to the host causing lesions on the skin (that can lead to secondary bacterial infections) and anaemia that can cause high mortality rates. The present study aimed to describe the life cycle of the branchiuran Dolops discoidalis (Bouvier, 1899) in order to contribute to the knowledge of the biology of this parasite and for future studies focused on its prevention and control in fish farming. Samples were collected in July 2021 from a fish pond located in Iquitos, Peru. Branchiurans were observed parasitizing the dorsal and ventral part of the body of Pseudoplatystoma punctifer (Castelnau, 1855). Parasites were collected using tweezers and placed in a container with water for later transfer to the laboratory. In the laboratory, collected branchiurans were placed in glass aquariums lined with plastic, waiting for mate and/or oviposition. Once oviposition was observed, eggs were transferred to 500 mL capacity beakers with constant aeration provided by a small diffuser stone connected to a hose. Eggs were observed once a day and changes in their morphology were photographed and registered. The observation of the eggs was carried out until the hatching of the juvenile. The life cycle of D. discoidalis from egg laying to juvenile hatching lasted 23 days. Since P. punctifer is being bred in captivity in the Peruvian Amazon, it is necessary to know aspects related to sanity, emphasizing the problems caused by parasites. The knowledge of the life cycle of D. discoidalis helps us to adopt measures to prevent and control the parasitism of this species and thus contribute to aquaculture activities in the Peruvian Amazon.

Study of the bionomy of the Ephydridae Family (Insecta: Diptera)

The larvae of the Ephydridae family feed on decaying plant material, algae, and other microscopic single-celled organisms and do not feed directly on plant tissue. Therefore, the damage they produce is indirect, since they are not phytophagous; but adults are vectors of bacteria, viruses and fungi which are transmitted on plants by perching and supporting their sucking mouthparts (proboscis). Also the larvae, when feeding, ingest spores of fungi or bacteria that then remain in the oral apparatus of the adult, and these, when flying and perching on the plants, transmit diseases. The high rate of reproduction of shore flies can give rise to a swarm of adults, which devalue the plants commercially. The objective of this paper and study of the bionomy of the Family Ephydridae. For this, a bibliographic survey of Ephydridae was carried out in the years 1926 to 2021. Only complete articles published in scientific journals and expanded abstracts presented in national and international scientific events were considered. Data were also obtained from platforms such as: World and Scielo.

Localization of Cdc14 Isoforms to Ciliary Structures in Tetrahymena thermophila

Cdc14 protein phosphatase is highly conserved across the eukaryotic kingdom, from single‐celled yeast and protozoa to multicellular organisms including mammals. In budding yeast, where it was first studied, Cdc14 is required for mitotic exit; however, this function is not widely conserved. In humans and mice, Cdc14A mutations cause deficiencies in hearing and male fertility due to defects in cilia formation and maintenance. There is evidence for Cdc14 localization to the basal bodies at the proximal end of cilia. The large number of cilia in the free‐living protozoan Tetrahymena thermophila make it an attractive model for molecular studies of cilia structure and function. Our goal is to determine the localization of Cdc14 isoforms to gain some insight into their cellular function and to test if Cdc14 cilia localization is broadly conserved. Interestingly, T. thermophilahas a larger number of Cdc14 isoforms than most organisms. Thus far, genes encoding three of the seven T. thermophilaCdc14 isoforms have been used to create C‐terminal gene fusions with YFP that are expressed in vivo. The constructs were inserted into the T. thermophilamacronuclear genome adjacent to the RPL29 gene and cell lines were selected due to the resulting conversion to cycloheximide resistance. Expression of the transgenes was regulated by a metallothionine promoter. Cells were examined via fluorescence microscopy in the presence and absence of cadmium. All three isoforms localize along ciliary rows and in the oral apparatus after induction during vegetative growth, consistent with basal body localization. No differences in localization have been noted between the three isoforms thus far. The presence of multiple isoforms with the same localization raises questions regarding the redundancy and/or functional specialization of Cdc14 in this highly ciliated organism.

Nuclear and Mitochondrial SSU rRNA Genes Reveal Hidden Diversity of Haptophrya Endosymbionts in Freshwater Planarians and Challenge Their Traditional Classification in Astomatia.

Like many other aquatic animals, freshwater planarians have also become partners of symbiotic ciliates from the class Oligohymenophorea. In the present study, we explored the hidden diversity and addressed the questionable systematic position of mouthless obligatory gut endosymbionts of freshwater planarians, using the nuclear and mitochondrial SSU rRNA genes. Although all isolated ciliates morphologically corresponded to a single species, molecular analyses suggested the existence of three genetically distinct entities: Haptophrya planariarum, Haptophrya dugesiarum nov. spec., and Haptophrya schmidtearum nov. spec. The two former species share the same planarian host, which indicates a speciation model involving one duplication event without host switching. Such a diversification pattern was recognized also in astome ciliates inhabiting megascolecid and glossoscolecid earthworms. The present multi-gene phylogenies along with the secondary structure of the mitochondrial 16S rRNA molecule, however, challenge the traditional classification of Haptophrya within the subclass Astomatia. Haptophrya very likely evolved from an orphan scuticociliate lineage by the loss of oral apparatus and by the transformation of the thigmotactic field into an adhesive sucker. Since astomy evolved multiple times independently within the Oligohymenophorea, the loss of cell mouth cannot be used as a sole argument for the assignment of Haptophrya to the Astomatia anymore.