Ecdysial cleavage lines of acariform mites (Arachnida, Acari)

Among mites the ancestral ecdysial cleavage line, or line of dehiscence (a), is inferred by outgroup comparison to be prodehiscent: U-shaped, passing around the front of the mite just above the insertions of the appendages, such that the mite ecloses anteriorly. From preserved and living individuals and exuviae, we found prodehiscence (or its slight variations) to be widespread in Acariformes. It appears to be pervasive in endeostigmatic mites, eupodine Prostigmata, and basal taxa in the Oribatida (Enarthronota, Palaeosomata); it is dominant in cleutherengone Prostigmata and is present in at least one anystine family (Caeculidae). Three general modes of dehiscence are considered to be derived within acariform mites. (1) Merodehiscence is a transverse splitting of the dorsal cuticle at or near the juncture of proterosoma and hysterosoma; it evolved separately in thrcc groups of Prostigmata (Tetranychidae, an undefined subgroup within Cheylctidae, and active instars of Parasitengona) and in a genus of Astigmata (Histiogaster). (2) Trarnsdehiscence is a transverse splitting of the dorsal hysterosomal cuticle anterior to the opisthosomal glands; it occurs in middle-derivative oribatid mites (the paraphyletic Desmonomata), and new observations show it to be widespread in Astigmata, lending support to the hypothesis that the latter group evolved from within Desmonomata. (3) Circumdehiscence is a circumferential splitting of the hysterosomal cuticle that may be incomplete anteriorly; it has long been known to characterize the monophyletic oribatid taxon Brachypylina, but it is convergent with a similar dehiscence in an unrelated family, Lohmanniidae. Transdehiscent and circumdehiscent mites eclose posteriorly. Astigmata exhibit the greatest variety of modes of dehiscence, including the three derived modes and a probable reversal to prodehiscence in Algophagidae. Furthermore, heteromorphic deutonymphs (hypopi) may ecdyse differently from other immature instars of the same species.     

Morphological evidence for the evolutionary origin of Astigmata (Acari: Acariformes)

A century ago, Antonio Berlese first discussed the close phylogenetic relationship between the large mite groups Oribatida and Astigmata. Since then, information having phylogenetic value has greatly increased and the paradigms within which we interpret it have changed. Herein I refine the general hypothesis that Astigmata originated within oribatid mites and suggest Malaconothridae as a possible sister group. Among the 14 apomorphies used to support the origin of Astigmata within oribatid mites are possession of lateral opisthosomal glands, regression of hysterosomal setal pair f1, paired prelarval denticles, partially internalized chelicerae with incomplete adaxial walls, an atelobasic rutellum, pretarsal condylophores that articulate posteriorly with the tarsus, a dorsally fused palp tibia and tarsus and transdehiscent ecdysis. A further 13 apomorphies support the origin of Astigmata at some level within Malaconothroidea. These include absence of an oblique labiogenal articulation, presence of a distal rutellar lamella, shortening of the palp tarsus, larval regression of hysterosomal seta f2, loss of the bothridial seta in all instars, and several losses and modifications of leg setae. The hypothesis brings to light evolutionary questions that were previously obscured by incorrect or inappropriate classifications. The nomenclatural problems that arise from it are best solved by considering Astigmata as a subgroup within Oribatida.     

Sperm structure and phylogeny of Astigmata

The Astigmata, a large and variable group, is still a subject of taxonomic dispute. Particularly, their origin from ancestors of the lower oribatid mites (e.g., Malaconothroidea) seems well documented by many lines of evidence. The structure of spermatozoa has been successfully applied to phylogenetic investigations in many animal groups. The aim of our study was to provide new data on spermatozoon structure in Astigmata and to consider its appropriateness in phylogenetic studies. The study reveals information on spermatozoa in 17 species of Astigmata (11 species studied for the first time) extending our knowledge to 18 species (one species known only from the literature) representing 12 families and 7 superfamilies. Spermatozoa have the same basic structure in all species: cells are multiform and the chromatin forms thin threads embedded directly in the cytoplasm; the acrosome is absent. The cytoplasm in most species contains electron-dense lamellae, varying in both number and arrangement within the cell. In Sarcoptoidea, electron-dense tubules in contact with lamellae margins were also observed in Psoroptidae (Psoroptes equi), whereas in two representatives of Sarcoptidae (Notoedres cati and Sarcoptes scabiei), only electron-dense tubules were found. In two species, Canestrinia sellnicki (Canestrinioidea: Canestriniidae) and Scutulanyssus obscurus (Analgoidea: Pteronyssidae), neither lamellae nor tubules were present. The mitochondria in a spermatozoon are usually gathered at the cell periphery and their structure is usually modified to form so-called mitochondrial derivatives. The chromatin threads are an autapomorphy strongly supporting the monophyly of Astigmata. As spermatozoa vary considerably between species in Astigmata, we deduce that sperm structure may be useful for phylogenetic analyses within the group. Several conclusions concerning the affinities within Astigmata are presented. Spermatology seems to be unhelpful, however, in questions on the origin of Astigmata (particularly for Astigmata-Oribatida relationships), since their sperm do not possess synapomorphies with sperm of the remaining groups of Acariformes, i.e., Endeostigmata, Prostigmata, and Oribatida.     

The phylogenetic relationship between Astigmata and Oribatida (Acari) as indicated by molecular markers

Astigmata comprise a diverse group of acariform mite species with a remarkable range of life histories, most of which involve parasitic or commensal relationships with other organisms. Several authors have suggested that Astigmata evolved as a paedomorphic clade from within Oribatida, and both morphology and gland-chemistry strongly suggest that their sister-clade is within the oribatid subgroup Desmonomata. The biologies of these groups contrast greatly, since oribatid mites are mostly soil-living detritivores and fungivores, and have life cycles that are much longer than those in Astigmata. We tested the hypothesis that Astigmata evolved from within Desmonomata using two molecular markers, the ribosomal 18S region (18S) and the nuclear elongation factor 1 alpha (ef1α) gene. Representative acariform mites included 28 species of Oribatida, eight of Astigmata, two of Prostigmata and two of Endeostigmata; outgroups included members of Opilioacariformes, Parasitiformes and Ricinulei. To minimize the possibility of long-branch attraction artifacts, we limited highly variable sites by removing gaps (18S) and third codon positions (ef1α) from the sequences. Maximum parsimony, neighbor-joining and Bayesian algorithms formed trees that consistently placed Astigmata outside monophyletic Oribatida, usually as sister-group of the endeostigmatid mite Alicorhagia sp. Analyses with and without outgroups resulted in similar topologies, showing no evidence for long-branch artifacts and leaving the conflict with morphological and biochemical data unexplained.     

A revised diagnosis of the feather mite genus Magimelia Gaud, 1961 (Pterolichoidea: Pterolichidae: Magimeliinae) and the description of three new species

Three new mite species of the genus Magimelia (Astigmata: Pterolichidae) are described from the plumage of various lapwings (Charadriidae: Vanellinae): M. breviloba n. sp. from Vanellus miles miles; M. thailandica n. sp. from V. indicus (type-host), V. duvaucelii and V. tricolor; and M. chilensis n. sp. from V. chilensis. An extended host range for M. dolichosikya Gaud, 1961 is given. A revised diagnosis of the genus and a key to known species are presented.     

Structural elucidation and synthesis of 3-hydroxybenzene-1,2-dicarbaldehyde from astigmatid mites.

The structure of a novel aromatic compound contained in the unidentified Rhizoglyhus mite (Acaridae: Astigmata) was elucidated, without its isolation, to be 3-hydroxybenzene-1,2-dicarbaldehyde (tentatively named gamma-acaridial) by a combination of GC/MS and GC/FT-IR together with knowledge of related mite compounds. The structure was confirmed by a 5-step synthesis, starting from methyl 3-hydroxybenzoate, in a 15% overall yield. The compound is widely distributed not only among Astigmata but also among Oribatida, although its biological function is obscure at present.     

Neohyadesia microtricha (Acari: Astigmata: Algophagidae): a new species from the sub-Antarctic

The sub-antarctic mite genus Neohyadesia (Acari: Astigmata) is known from two described taxa: N. signyi from Signy Island (South Orkney Islands, South Atlantic Province), and a subspecies, N. s. punctulata from Ile Kerguelen (South Indian Province). This paper describes a second species distinguishable by, in particular, cuticular microtrichae covering the dorsal surface. The new species, N. microtricha sp. nov., has a similarly disjunct sub-antarctic distribution, occurring on both Marion (SIP) and South Georgia (SAP) islands. A systematic synopsis of the sub-antarctic algophagine mites is given. Accepted: 30 June 2000     

Molecular phylogeny of oribatid mites (Oribatida, Acari): evidence for multiple radiations of parthenogenetic lineages

Nucleotide sequences of the D3 expansion segment and its flanking regions of the 28S rDNA gene were used to evaluate phylogenetic relationships among representative sexual and asexual oribatid mites (Oribatida, Acariformes). The aim of this study was to investigate the hypothesis that oribatid mites consist of species-rich clusters of asexual species that may have radiated while being parthenogenetic. Furthermore, the systematic position of the astigmate mites (Astigmata, Acariformes) which have been hypothesised to represent a paedomorphic lineage within the oribatid mites, is investigated. This is the first phylogenetic tree for oribatid mites s.l. (incl. Astigmata) based on nucleotide sequences. Intraspecific genetic variation in the D3 region was very low, confirming the hypothesis that this region is a good species marker. Results from neighbour joining (NJ) and maximum parsimony (MP) algorithms indicate that several species-rich parthenogenetic groups like Camisiidae, Nanhermanniidae and Malaconothridae are monophyletic, consistent with the hypothesis that some oribatid mite groups diversified despite being parthenogenetic. The MP and maximum likelihood (ML) method indicated that the D3 region is a good tool for elucidating the relationship of oribatid mite species on a small scale(genera, families) but is not reliable for large-scale taxonomy, because branches from the NJ algorithm collapsed in the MP and ML tree. In all trees calculated by different algorithms the Astigmata clustered within the oribatid mites, as proposed earlier.     

Structural Elucidation and Synthesis of 3-Hydroxybenzene-1,2-dicarbaldehyde from Astigmatid Mites

The structure of a novel aromatic compound contained in the unidentified Rhizoglyhus mite (Acaridae: Astigmata) was elucidated, without its isolation, to be 3-hydroxybenzene-1,2-dicarbaldehyde (tentatively named γ-acaridial) by a combination of GC/MS and GC/FT-IR together with knowledge of related mite compounds. The structure was confirmed by a 5-step synthesis, starting from methyl 3-hydroxybenzoate, in a 15% overall yield. The compound is widely distributed not only among Astigmata but also among Oribatida, although its biological function is obscure at present.     

Five new species of Rhinonyssidae (Mesostigmata) and one new species of Dermanyssus (Mesostigmata: Dermanyssidae) from birds of Alberta and Manitoba, Canada

Three major lineages of mites are parasitic in the nasal passages of birds, i.e., Rhinonyssidae (Mesostigmata), Ereynetidae (Prostigmata), Cytoditidae, and Turbinoptidae (Astigmata). The most diverse family of avian nasal mites is Rhinonyssidae, which include obligate hematophagous endoparasites of nonratite birds worldwide. Nasal mites have been surveyed extensively in the United States, yet there has never been a Canadian survey. There are only 4 published, and 3 unpublished, rhinonyssid species records from birds in Canada. While surveying the nasal mites associated with birds of Alberta and Manitoba (western Canada), 1 new species of Dermanyssus and 5 new species of Rhinonyssidae were recovered. Herein, I describe and illustrate Dermanyssus diphyes n. sp., Ptilonyssus calvaria n. sp., P. nivalis n. sp., P. pinicola n. sp., P. plesiotypicus n. sp., and Sternostoma setifer n. sp.     

The idiosomal chaetotaxy of astigmatid mites

Within the Astigmata, setal homologies with the general chaetotaxic systems developed for acariform mites by F. Grandjean have never been convincingly established. This study deals with all body regions, exclusive of legs and gnathosoma, mostly utilizing as models astigmatid species from three different families. Six hypotheses which attempt to explain the ontogeny of segments, setae and cupules in the caudal bend region are compared using three-dimensional views obtained by scanning electron microscopy. The hypotheses are evaluated by in-group comparisons testing their consistency with presumed segmental boundaries, and by out-group comparisons with oribatid mites. The strongest, most parsimonious hypothesis suggests that larval astigmatid mites possess segment F, but not its setae, and the two pairs posterior to segment F are h _l and h ₂, whilst the five setae added in the protonymph are h ₃, f ₂ and ps _1–3. Six pairs of structures on the deutonymphal anal plate are identified as modified setae, and evidence supporting their homologies with setae of other instars is discussed for the first time. A comparison of the principal chaetotaxic systems used for the dorsal and anal regions of the Astigmata is presented. Application of Grandjean's setal signatures to these regions, as well as to the coxisternal and genital regions, is discussed and illustrated by examples.     

A new canestriniid mite, Haitlingeria longilobata n. g., n. sp. (Acari: Astigmata: Canestriniidae), parasitising Serrognathus platymelus castauicolor Motschulsky (Coleoptera: Lucanidae) from South Korea

Haitlingeria longilobata n. g., n. sp. (Acari: Astigmata: Canestriniidae) is described from Serrognathus platymelus castauicolor Motschulsky (Coleoptera: Lucanidae) from South Korea. Diagnostic features include: the presence of two long lobes on the male opisthosoma; the idiosoma length is similar to the idiosoma width; the hysterosoma is ornamented by distinct reticulate pattern; a suture is present separating the propodosoma from the hysterosoma; the adanal suckers are well developed on the male; there are four pairs of ultralong setae; and solenidion φ on tibia I is very long.     

Densities of Collembola and Acarina in the soil and litter of three indigenous South Australian forests related to layer,site and seasonal differences

A quantitative study was made of the micro-arthropod fauna in the litter and two soil layers at three South Australian forest sites (designated ‘dry’ medium’ and ‘wet’) using data taken at monthly intervals over 2 years. This study examined variations in density estimates of the major taxonomic groups of Acarina and Collembola that were associated with sample depth, site and season. There were substantial differences in the proportions of variation attributed to layer, site and seasonal effects. Most variation was associated with layer differences, being greatest in the acarine Prostigmata and in the collembolan Onychiuridae. Only the acarine Astigmata had slightly more variation between sites than between layers. Seasonal variation exceeded site variation in all collembolan groups except the Entomobryidae. In the acarine groups estimated ratios of seasonal to site variation were 6.1, 1.6, 1.0 and 0.4 for the Mesostigmata, Prostigmata, Cryptostigmata and Astigmata, respectively. Some variations due to inconsistencies in the above patterns were significant statistically but were small compared with variations associated with the seasonal, layer and site effects. Densities of all animals had marked seasonal variation which was broadly similar to that of rainfall in the warm temperate, mediterranean type climate of the region. Minimum density and activity occurred in about the last week in January, a period of maximum temperature and low soil moisture content; maxima were usually about 7 months later. This contrasts with warm and cool temperate areas of Australia with summer rainfall, where peak densities have been recorded in summer. The Mesostigmata, Astigmata, Podundae and Onychiuridae patterns of seasonal variation did not differ significantly with layer or site differences. The remaining groups had significant differences with layers and sites, the former being larger. Density minima and maxima were generally later going from litter to lower soil, about 2.5–8 weeks for density maxima and 0–4 weeks for minima. Groups with significant lags showed reduced amplitude in their seasonal variation with increased depth. There was little seasonal variation in the relative proportions of all animal groups.     

Mite species identification in the production of allergenic extracts for clinical use and in environmental samples by ribosomal DNA amplification

The identification of allergy‐causing mites is conventionally based on morphological characters. However, molecular taxonomy using ribosomal DNA (rDNA) may be particularly useful in the analysis of mite cultures and purified mite fractions in the production of allergenic extracts. Full‐length internal transcribed spacers (ITS1 and ITS2) were obtained from Dermatophagoides farinae, Dermatophagoides pteronyssinus, Dermatophagoides microceras and Euroglyphus maynei (Astigmata: Pyroglyphidae), Glycyphagus domesticus and Lepidoglyphus destructor (Astigmata: Glycyphagidae), Tyrophagus fanetzhangorum, Tyrophagus putrescentiae, Tyrophagus longior, Tyrophagus neiswanderi, Acarus farris and Acarus siro (Astigmata: Acaridae), and Blomia tropicalis (Astigmata: Echymopodidae), using mite‐specific primers. Polymerase chain reaction (PCR) products were digested with HpaII and RsaI restriction enzymes in order to produce species‐specific PCR restricted fragment length polymorphism (RFLP) profiles. A semi‐nested re‐amplification step was introduced before the RFLP in order to apply the method to environmental samples. Results demonstrate that rDNA sequences can be used for the unambiguous identification of mite species. The PCR–RFLP system allows the identification of species in purified mite fractions when the availability of intact adult mite bodies for morphological identification is limited. This reliable and straightforward PCR–RFLP system and the rDNA sequences obtained can be of use in the identification of allergy‐causing mite species.     

A new classification of membrane protein crystals

Although being much smaller than the number of soluble proteins in the Protein Data Bank, the number of membrane proteins therein now approaches 700, and a statistical analysis becomes meaningful. Such an analysis showed that the conventional subdivision into monotopic, β-barrel and α-helical membrane proteins is appropriate but should be amended by a classification according to the detergent micelle structure in the crystal, which can be derived from the packing of the membrane-immersed parts of the proteins. The crystal packing density is specific for the three conventional types of membrane proteins and soluble proteins. It is also specific for three observed detergent arrangements that are micelle pockets, micelle filaments and micelle sheets, demonstrating that the detergent structure affects crystallization. The packing density distribution of crystals from integral membrane proteins has approximately the same shape as that of soluble proteins but is by a factor of two broader and shifted to lower density. It seems unlikely that the differences can be explained by a mere solvent expansion due to the required detergent. The crystallized membrane proteins were further analyzed with respect to protein mass, oligomerization and crystallographic asymmetric unit, space group, crystal ordering and symmetry. The results provide a new view on membrane proteins.     

DNA barcoding and minibarcoding as a powerful tool for feather mite studies

Feather mites (Astigmata: Analgoidea and Pterolichoidea) are among the most abundant and commonly occurring bird ectosymbionts. Basic questions on the ecology and evolution of feather mites remain unanswered because feather mite species identification is often only possible for adult males, and it is laborious even for specialized taxonomists, thus precluding large‐scale identifications. Here, we tested DNA barcoding as a useful molecular tool to identify feather mites from passerine birds. Three hundred and sixty‐one specimens of 72 species of feather mites from 68 species of European passerine birds from Russia and Spain were barcoded. The accuracy of barcoding and minibarcoding was tested. Moreover, threshold choice (a controversial issue in barcoding studies) was also explored in a new way, by calculating through simulations the effect of sampling effort (in species number and species composition) on threshold calculations. We found one 200‐bp minibarcode region that showed the same accuracy as the full‐length barcode (602 bp) and was surrounded by conserved regions potentially useful for group‐specific degenerate primers. Species identification accuracy was perfect (100%) but decreased when singletons or species of the Proctophyllodes pinnatus group were included. In fact, barcoding confirmed previous taxonomic issues within the P. pinnatus group. Following an integrative taxonomy approach, we compared our barcode study with previous taxonomic knowledge on feather mites, discovering three new putative cryptic species and validating three previous morphologically different (but still undescribed) new species.     

A new species ofChaetomium from house dust

A new species ofChaetomium, C. umbratile, is described from Japan. The species is based on three specimens isolated from house dust samples in asthmatic patients' dwellings. It is characterized by long, wavy and irregularly branched terminal hairs, which are intermingled with short straight hairs, and nearly globose to broadly ellipsoidal ascospores with a slightly subapical or sometimes lateral germ pore.     

A new canestriniid mite,Bircericola bertrami n. g., n. sp. (Acari: Astigmata: Canestriniidae), parasitic on tenebrioniid beetles (Coleoptera: Tenebrionidae) from Tunisia

The new genus Bircericola (Acari: Astigmata: Canestriniidae) and new species Bircericola bertrami from undetermined tenebrioniid beetles from Tunisia are described. Diagnostic features include: dorsal integument covered by longitudinal lines; suture separating propodosoma from hysterosoma present; male adanal suckers well developed; two pairs of paranal setae in males and six pairs in females; tarsi I-II very short (<30 m); and solenidia I and II subequal in length to setae cG I and cG II, respectively.     

The soil Acari of barley plots with different cultural treatments

Sixty-four species of Acari were extracted by wet sieving and salt flotation from soil in four barley plots sampled on five occasions between 23 May and 15 August 1975. Over half the species were Prostigmata. The most abundant species wereScutacarus longiusculus (Karafiat) (Scutacaridae, Prostigmata),Bakerdania gracilis (Krczal) (Pygmephoridae, Prostigmata), andTyrophagus longior (Gervais) (Acaridae, Astigmata).Only three species (B. gracilis, T. longior andPseudopygmephorus sellnicki (Krczal) (Pygmephoridae)) contributed more than 2% of the individuals and occurred in more than 25% of the samples in all plots.Mean population densities ranged from 41 to 216 thousand/m², with highest density occurring in a conventionally ploughed and cultivated plot and lowest in a direct drilled plot. Prostigmata accounted for 46–85% of the total populations in the various plots.Twelve species were recorded from decaying crop residues on the soil surface; these included some of the most abundant species recorded from growing barley in a related study. Soil and crop residues were the main sources of most of the dominant species colonizing the growing barley crop.The barley plots had greater numbers of Prostigmata and Astigmata but fewer Cryptostigmata and Mesostigmata than were extracted by a high gradient canister technique from adjacent grass ley pasture sampled in its second and third years (1976 and 1977). Biomass in the older ley was far greater than in the barley. There were higher numbers of species of intermediate relative abundance (0.1–5%) in the ley, indicating more mature communities than in the barley plots.     

Identification of astigmatid mites using the second internal transcribed spacer (ITS2) region and its application for phylogenetic study

The second internal transcribed spacer (ITS2) of nuclear ribosomal DNA from 73 specimens of Astigmata was analyzed by PCR amplification and DNA sequencing. The length of the ITS2 region varied from 282 to 592 bp. The interspecific variation based on consensus sequences was more than 4.1%, while the intraspecific or intra-individual variation was from 0 to 5.7%. The variation between geographically separated populations (0–3.2%) was almost the same as the variation within strains. The sequences of the ITS2 region of Astigmata were concluded to be species-specific. The phylogenetic tree inferred from the ITS2 region supported Zachvatkins morphological classification in the subfamily Rhizoglyphinae. The species-specific ITS2 sequence is useful for the species identification of astigmatid mites and for studying low-level phylogenetic relationships.Chemical Ecology of Astigmatid Mites LXXVThis revised version was published online in May 2005 with a corrected cover date.