51 research outputs found

    the alterations of plumage of parasitic origin

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    Described herein are the main lesions to the plumage caused by insects and mites, both on the vane or the calamus of feathers. Practical data are given, aimed to make a correct differential diagnosis. Mallophaga cut the barbs of feathers, whereas dermestidae can cut also the rachis. Mites make holes in the vane of feathers and sometimes they stick the barbs the ones to the others or they attack the calamus both inside and by digging tunnels in the outside wall of the calamus causing the fall of feathers

    Complete mitochondrial genomes of the human follicle mites Demodex brevis and D. folliculorum: novel gene arrangement, truncated tRNA genes, and ancient divergence between species

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    BACKGROUND: Follicle mites of the genus Demodex are found on a wide diversity of mammals, including humans; surprisingly little is known, however, about the evolution of this association. Additional sequence information promises to facilitate studies of Demodex variation within and between host species. Here we report the complete mitochondrial genome sequences of two species of Demodex known to live on humans—Demodex brevis and D. folliculorum—which are the first such genomes available for any member of the genus. We analyzed these sequences to gain insight into the evolution of mitochondrial genomes within the Acariformes. We also used relaxed molecular clock analyses, based on alignments of mitochondrial proteins, to estimate the time of divergence between these two species. RESULTS: Both Demodex genomes shared a novel gene order that differs substantially from the ancestral chelicerate pattern, with transfer RNA (tRNA) genes apparently having moved much more often than other genes. Mitochondrial tRNA genes of both species were unusually short, with most of them unable to encode tRNAs that could fold into the canonical cloverleaf structure; indeed, several examples lacked both D- and T-arms. Finally, the high level of sequence divergence observed between these species suggests that these two lineages last shared a common ancestor no more recently than about 87 mya. CONCLUSIONS: Among Acariformes, rearrangements involving tRNA genes tend to occur much more often than those involving other genes. The truncated tRNA genes observed in both Demodex species would seem to require the evolution of extensive tRNA editing capabilities and/or coevolved interacting factors. The molecular machinery necessary for these unusual tRNAs to function might provide an avenue for developing treatments of skin disorders caused by Demodex. The deep divergence time estimated between these two species sets a lower bound on the time that Demodex have been coevolving with their mammalian hosts, and supports the hypothesis that there was an early split within the genus Demodex into species that dwell in different skin microhabitats. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/1471-2164-15-1124) contains supplementary material, which is available to authorized users

    Funktionelle Anatomie und phylogenetische Abwandlung des männlichen Genitalsystems der actinotrichen Milben (Acari)

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    The goal of this paper is to expand the knowledge about the functional anatomy of the male genital system of actinotrichid mites and to contribute to phylogenetic questions. Histological studies were carried out on three taxa: Ameronothrus lineatus (Oribatida, Brachypylina), Linopodes spec. (Prostigmata, Eupodoidea) and Tydeus californicus (Prostigmata, Tydeoidea).The proximal genital system of the taxa shows a rather consistent arrangement, which is in agreement to those of other Actinotrichida. It consists of a testis, which is divided into a germinal and a glandular part, and paired vasa deferentia which fuse before leading into the ductus ejaculatorius.The distal genital system of the three taxa consists of a ductus ejaculatorius and a genital chamber, with some profound differences in the specific arrangements of Oribatida and Prostigmata. There is no evidence for homology of the particular structures in both taxa. The ductus ejaculatorius of Linopodes spec. is divided into three chambers, an arrangement which is known from other Prostigmata as well as from Endeostigmata. Furthermore, an unpaired anterior accessory gland can be found in Linopodes spec. and Tydeus californicus, which is also known from other prostigmatid and endeostigmatid mites. Thus, the formation of spermatophores of Linopodes spec. is probably homologous to that described from other Prostigmata.Ultrastructural results of the accessory organ of Ameronothrus lineatus do not give any evidence for a glandular function of this organ, as hypothesized in previous studies.The spermatozoa of Ameronothrus lineatus exhibit structures typical for higher oribatida, i.e., loss of an acrosome complex, modification of mitochondria and possession of electron dense bodies. In the spermatogenesis of Linopodes spec. and Tydeus californicus, some characteristics can be found, which support a close relationship of Eupodoidea and Tydeoidea

    Origin and higher-level diversification of acariform mites – evidence from nuclear ribosomal genes, extensive taxon sampling, and secondary structure alignment

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    Abstract Background Acariformes is the most species-rich and morphologically diverse radiation of chelicerate arthropods, known from the oldest terrestrial ecosystems. It is also a key lineage in understanding the evolution of this group, with the most vexing question whether mites, or Acari (Parasitiformes and Acariformes) is monophyletic. Previous molecular studies recovered Acari either as monophyletic or non-monophyletic, albeit with a limited taxon sampling. Similarly, relationships between basal acariform groups (include little-known, deep-soil 'endeostigmatan' mites) and major lineages of Acariformes (Sarcoptiformes, Prostigmata) are virtually unknown. We infer phylogeny of chelicerate arthropods, using a large and representative dataset, comprising all main in- and outgroups (228 taxa). Basal diversity of Acariformes is particularly well sampled. With this dataset, we conduct a series of phylogenetically explicit tests of chelicerate and acariform relationships and present a phylogenetic framework for internal relationships of acariform mites. Results Our molecular data strongly support a diphyletic Acari, with Acariformes as the sister group to Solifugae (PP =1.0; BP = 100), the so called Poecilophysidea. Among Acariformes, some representatives of the basal group Endeostigmata (mainly deep-soil mites) were recovered as sister-groups to the remaining Acariformes (i. e., Trombidiformes + and most of Sarcoptiformes). Desmonomatan oribatid mites (soil and litter mites) were recovered as the monophyletic sister group of Astigmata (e. g., stored product mites, house dust mites, mange mites, feather and fur mites). Trombidiformes (Sphaerolichida + Prostigmata) is strongly supported (PP =1.0; BP = 98–100). Labidostommatina was inferred as the basal lineage of Prostigmata. Eleutherengona (e. g., spider mites) and Parasitengona (e. g., chiggers, fresh water mites) were recovered as monophyletic. By contrast, Eupodina (e. g., snout mites and relatives) was not. Marine mites (Halacaridae) were traditionally regarded as the sister-group to Bdelloidea (Eupodina), but our analyses show their close relationships to Parasitengona. Conclusions Non-trivial relationships recovered by our analyses with high support (i.e., basal arrangement of endeostigmatid lineages, the position of marine mites, polyphyly of Eupodina) had been  proposed by previous underappreciated morphological studies. Thus, we update currently the accepted taxonomic classification to reflect these results: the superfamily Halacaroidea Murray, 1877 is moved from the infraorder Eupodina Krantz, 1978 to Anystina van der Hammen, 1972; and the subfamily Erythracarinae Oudemans, 1936 (formerly in Anystidae Oudemans, 1902) is elevated to family rank, Erythracaridae stat. ressur., leaving Anystidae only with the nominal subfamily. Our study also shows that a clade comprising early derivative Endeostigmata (Alycidae, Nanorchestidae, Nematalycidae, and maybe Alicorhagiidae) should be treated as a taxon with the same rank as Sarcoptiformes and Trombidiformes, and the scope of the superfamily Bdelloidea should  be changed. Before turning those findings into nomenclatural changes, however, we consider that our study calls for (i) finding shared apomorphies of the early derivative Endeostigmata clade and the clade including the remaining Acariformes; (ii) a well-supported hypothesis  for Alicorhagiidae placement; (iii) sampling the families Proterorhagiidae, Proteonematalycidae and Grandjeanicidae not yet included in molecular analyses; (iv) undertake a denser sampling of clades traditionally placed in Eupodina, Anystina (Trombidiformes) and Palaeosomata (Sarcoptiformes), since consensus networks and Internode certainty (IC) and IC All (ICA) indices indicate high levels of conflict in these tree regions. Our study shows that regions of ambiguous alignment may provide useful phylogenetic signal when secondary structure information is used to guide the alignment procedure and provides an R implementation to the Bayesian Relative Rates test.http://deepblue.lib.umich.edu/bitstream/2027.42/113097/1/12862_2015_Article_458.pd

    Spinnvermögen bei Rhagidiidae : (Acari, Prostigmata)

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    Die erstmals für die Familie der Rhagidiidae entdeckte Spinnvermögen istt bei allen mobilen Jugendstasen vorhanden und konnte für folgende Arten nachgewiesen werden: Rhagidia longisensilla, Rhagidia pratensis, Rhagidia reflexa, Rhagidia mucronata, Rhagidia arenaria, Rhagidia halophila und Rhagidia danica. Die Milben spinnen sich am Ende einer Stase ein. Bei Rhagidia pratensis und Rhagidia reflexa sind diese Gespinste artspezifisch. Rhagidia longisensilla besitzt auch als adultes Tier ein Spinnvermögen. Die angelegten Netze erfüllen bei ihr folgende Funktionen: Schutz, Nahrungserwerb, Häutungskokon und Brutfürsorge. Als Vertreter der .Eleutherengona" konnten bei Rhagidia 4 Drüsen am podocephalischen Kanal nachgewiesen werden, so daß für die Prostigmata ein in den Grundzügen übereinstimmendes Drüsensystem anzunehmen ist. Die bei den podocephalischen Kanäle münden in der Chelicerenrinne. Die infracapituläre Drüse besitzt eigene Ausführungsgänge, die dorsal auf dem Infracapitulum münden. Die 1. und 3. podocephalische Drüse dienen als Spinndrüsen. Die 4. podocephalische Drüse ist eine Coxaldrüse und besitzt proximal einen Sacculus, dessen Epithelzellen z. T. 10 um groß sind und einen drüsigen Charakter besitzen.The spinning ability, for the first time discovered in the familiy Rhagidiiae, is presend in all mobil youth stases and could be confirmed in the following species: Rhagidia longisensilla, Rhagidia pratensis, Rhagidia reflexa, Rhagidia mucronata, Rhagidia arenaria, Rhagidia halophila and Rhagidia danica. The mites spinn a web around themselves at the end of each stase. In the case of R. pratensis and R. reflexa webs are speclflc to the species. By R. longisensi/la adult mites pos ses this spinning ability. They use the webs in the following functions: protection, catching prey, moulting nets and egg-preservation. By Rhagidia, as a member of the "Eleutherengona", 4 glands are situated at the podocephalic canal, so that a basicaly same glandsystem in the Prostigmata is presumed. Both podocephalic canals discharge into the cheliceral groove. The infracapitular gland has its own ducts discharging dorsaly on the infracapitulum. The 1st and 3 rd podocephalic glands are used for silk production. The 4th podocephalic gland corresponds with the coxal gland and ends in a proximal sacculus with epithal cells ranging up to 10 urn, partially with secretory function

    Myobiid mites (Trombidiformes, Myobiidae) of the golden bat Mimon cozumelae from Mexico. Description of the male and tritonymph of Ioanella mimon and new records of Eudusbabekia mimon

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    The male and the tritonymph of Ioanella mimon are described for the first time parasitizing to Mimon cozumelae from Yucatan, Mexico. Male of I. mimon is characterized by the presence of legs I with the tibia and tarsus fused forming a small complex devoided of apical claws, legs II–IV with two claws, setae vi at level of anterior end of genital plate, genital plate rounded with an anterior projection, all intercoxal setae short; while the tritonymph is characterized by the presence of legs I unequal; legs II–IV with 2-1-1 claws, and posterior region of dorsal idiosoma with 3 pairs of cylindrical and toothed setae. Additionally, we include new locality and host records for Eudusbabekia mimon which was also found on M. cozumelae. Both species were described originally in association with Mimon bennettii at Bartica, Guyana

    Pterygosomatid mites from Cuba, with the description of a new species of Bertrandiella (Acari: Prostigmata: Pterygosomatidae)

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    AbstractBertrandiella griseldae, new species is described based on specimens found on the gecko Tarentola americana. Additionally, the female of Geckobiella javieri is described for the first time, new data for larvae and deutonymphs are presented, and a summary of the leg chaetotaxy for Geckobia tarentolae is reported. A taxonomic identification key for the mite species of Pterygosomatidae ectoparasitic on lizards from Cuba is also provided

    Evolution and diversity of Rickettsia bacteria

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    Background: Rickettsia are intracellular symbionts of eukaryotes that are best known for infecting and causing serious diseases in humans and other mammals. All known vertebrate-associated Rickettsia are vectored by arthropods as part of their life-cycle, and many other Rickettsia are found exclusively in arthropods with no known secondary host. However, little is known about the biology of these latter strains. Here, we have identified 20 new strains of Rickettsia from arthropods, and constructed a multi-gene phylogeny of the entire genus which includes these new strains.Results: We show that Rickettsia are primarily arthropod-associated bacteria, and identify several novel groups within the genus. Rickettsia do not co-speciate with their hosts but host shifts most often occur between related arthropods. Rickettsia have evolved adaptations including transmission through vertebrates and killing males in some arthropod hosts. We uncovered one case of horizontal gene transfer among Rickettsia, where a strain is a chimera from two distantly related groups, but multi-gene analysis indicates that different parts of the genome tend to share the same phylogeny.Conclusion: Approximately 150 million years ago, Rickettsia split into two main clades, one of which primarily infects arthropods, and the other infects a diverse range of protists, other eukaryotes and arthropods. There was then a rapid radiation about 50 million years ago, which coincided with the evolution of life history adaptations in a few branches of the phylogeny. Even though Rickettsia are thought to be primarily transmitted vertically, host associations are short lived with frequent switching to new host lineages. Recombination throughout the genus is generally uncommon, although there is evidence of horizontal gene transfer. A better understanding of the evolution of Rickettsia will help in the future to elucidate the mechanisms of pathogenicity, transmission and virulence

    Anatomie des Verdauungstraktes der Rhagidiidae (Acari, Trombidiformes)

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    Die Rhagidien ernähren sich von kleinen weichhäutigen Arthropoden. Der Verdauungstrakt besteht aus folgenden Abschnitten: Oesophagus, Pharynx, Ventrikel mit Caecen, Colon, Postcolon und Rectum. Der Ventrikel ist nicht blind geschlossen sondern mit dem Colon verbunden. Nach der Resorption im Ventrikel sammeln sich die mit Zellfaeces beladenen ExkretzeIlen sowie unverdauliche Nahrungsreste aus dem Beutetier und dessen Exkrete zu einem Pfropf, der in den »Exkretionsdarm« übertritt. Dieser ist durch einen Sphinkter in ein Colon und Postcolon unterteilt, wodurch am lebenden Tier 2 hintereinanderliegende »Kotballen« zu sehen sind. Nur im Postcolon findet die Bildung von Exkreten statt. An den Exkretionsdarm schließt das ektodermale Rectum an. Der als ursprünglich anzusehende Verdauungstrakt der Rhagidien läßt sich mit dem der Sarcoptiformes homologisieren. Es wird der Versuch unternommen, eine Entwicklungsreihe des Verdauungstraktes für die Prostigmata aufzustellen. Anhand unterschiedlicher Ausgestaltung des Exkretionsdarmes bei verschiedenen trombidiformen Milben wird eine Hypothese aufgestellt, wie es morphologisch zu der möglicherweise vorhandenen Abtrennung des »Exkretlonsorqans« bei einigen Milben gekommen sein könnte. Der blind geschlossene Mitteldarm kann nicht mehr uneingeschränkt als kennzeichnendes Merkmal der Trombidiformes angesehen werden.TheRhagidiid mites prey upon soft skinned small-arthropods. The alimentary canal consists of oesophagus, pharynx, ventriculus with caecen, colon and postcolon. The ventriculus does not end blindly but is connected with the colon. After resorption in the ventriculus the cellfaeces and the food-rests clump together into a bolus which then enters the excretory gut. This part of the alimentary canal is devided into a colon and postcolon by a sphincter. This is why in living mites often 2 excrement-balls can be seen, The excretory gut leeds into the ectodermal rectum. The alimentary canal of the Rhagidiid mites can be considered primeval and is to be homologized with that of the Sarcoptiformes. The aim of the study is to construate a developmental sequence of the alimentary canal by the Prostigmata. According to the different forms of the excretory gut of the Prostigmata a hypothesis can be formed about how the detached excretory organ may have developed. The blind-ending ventriculus can no longer be regarded as typical of the Trombidiformes
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