It is generally thought that the anterior border of the opisthosoma of acariform mites is delineated by the disjugal furrow, but there is no evidence to support this other than the superficial ...appearance of tagmosis in some oribatids. It is proposed herein that the disjugal furrow is an apomorphic feature that does not correspond with any segmental borders. Although the disjugal furrow is absent from Proteonematalycus wagneri Kethley, the visible body segments of this species indicate that this furrow, when present, intersects the metapodosoma. Therefore, the disjugal furrow does not delineate the anterior border of the opisthosoma. Instead, this border is between segments D and E (segments VI and VII for all arachnids). This hypothesis can be accommodated by a new model in which the proterosoma warps upwards relative to the main body axis. This model, which is applicable to all Acariformes, if not all arachnids, explains the following phenomena: 1) the location of the gnathosomal neuromeres within the idiosoma; 2) the relatively posterior position of the paired eyes; 3) the shape of the synganglion; 4) the uneven distribution of legs in most species of acariform mites with elongate bodies.
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•Phylogeny inferred for Acariform mites, the largest chelicerate lineage.•Relationships of the four-legged mites (Eriophyoidea) are analyzed.•Total evidence tree (6 genes): it is ...sister to family Nematalycidae (Endeostigmata).•Nuclear protein-coding genes (3 genes): it is sister to Eupodina (Trombidiformes).•This result is analyzed using different phylogenetically explicit approaches.
Eriophyoid, or four-legged mites, represent a large and ancient radiation of exclusively phytophagous organisms known from the Triassic (230 Mya). Hypothesizing phylogenetic relatedness of Eriophyoidea among mites is a major challenge due to the absence of unambiguous morphological synapomorphies, resulting in ten published hypotheses placing eriophyoids in various places in the acariform tree of life. Here we test the evolutionary relationships of eriophyoids using six genes and a representative taxonomic sampling of acariform mites. The total evidence analysis places eriophyoids as the sister group of the deep soil-dwelling, vermiform family Nematalycidae (Endeostigmata). This arrangement was supported by the rDNA and CO1 partitions. In contrast, the nuclear protein partition (genes EF1-α, SRP54, HSP70) suggests that Eriophyoidea is sister to a lineage including Tydeidae, Ereynetidae, and Eupodidae (Eupodina: Trombidiformes). On both of these alternative topologies, eriophyoids appear as a long branch, probably involving the loss of basal diversity in early evolution. We analyze this result by using phylogenetically explicit hypothesis testing, investigating the phylogenetic signal from individual genes and rDNA stem and loop regions, and removing long branches and rogue taxa. Regardless of the two alternative placements, (i) the cheliceral morphology of eriophyoids, one of the traits deemed phylogenetically important, was likely derived directly from the plesiomorphic acariform chelicerae rather than from the modified chelicerae of some trombidiform lineages with a reduced fixed digit; and (ii) two potential synapomorphies of Eriophyoidea+Raphignathina (Trombidiformes) related to the reduction of genital papillae and to the terminal position of PS segment can be dismissed as result of convergent evolution. Our analyses substantially narrow the remaining available hypotheses on eriophyoid relationships and provide insights on the early evolution of acariform mites.
Eriophyoid mites represent a hyperdiverse, phytophagous lineage with an unclear phylogenetic position. These mites have succeeded in colonizing nearly every seed plant species, and this evolutionary ...success was in part due to the mites' ability to induce galls in plants. A gall is a unique niche that provides the inducer of this modification with vital resources. The exact mechanism of gall formation is still not understood, even as to whether it is endogenic (mites directly cause galls) or exogenic (symbiotic microorganisms are involved). Here we (i) investigate the phylogenetic affinities of eriophyoids and (ii) use comparative metagenomics to test the hypothesis that the endosymbionts of eriophyoid mites are involved in gall formation. Our phylogenomic analysis robustly inferred eriophyoids as closely related to Nematalycidae, a group of deep-soil mites belonging to Endeostigmata. Our comparative metagenomics, fluorescence in situ hybridization, and electron microscopy experiments identified two candidate endosymbiotic bacteria shared across samples, however, it is unlikely that they are gall inducers (morphotype1: novel Wolbachia, morphotype2: possibly Agrobacterium tumefaciens). We also detected an array of plant pathogens associated with galls that may be vectored by the mites, and we determined a mite pathogenic virus (Betabaculovirus) that could be tested for using in biocontrol of agricultural pest mites.
Due to the inadequacy of prior descriptions and the absence of redescriptions, studies on the taxonomy of the subgenus Anthoseius De Leon (Acari: Phytoseiidae) have become challenging and often cause ...confusion among taxonomists. Typhlodromus (Anthoseius) ghanii (Muma) and T. (A.) loralaiana (Muma) were described from Pakistan almost sixty years ago. Their original descriptions are not very detailed, being based on simple drawings and an absence of diagnostic characters that include measurements of dorsal setae. Most likely due to its inadequate description, T. (A.) ghanii was not recognized by acarologists and was therefore repeatedly described as a new species under different names. We examined the holotypes of T. (A.) homalii Gupta and T. (A.) sagaricus Karmakar et al. concluding both species to be junior synonyms of T. (A.) ghanii. Moreover, T. (A.) kuznetsovi (Denmark and Welbourn), described from Tajikistan, is proposed as a new junior synonym of T. (A.) loralaiana based on the examination of their holotypes. Hence, complementary descriptions of T. (A.) ghanii and T. (A.) loralaiana, based on their holotypes, are provided to facilitate species identification and to improve their diagnosis.
The setae in Eriophyoidea are filiform, slightly bent and thickened near the base. Confocal microscopy indicates that their proximal and distal parts differ in light reflection and autofluorescence. ...Approximately 50 genera have atypically shaped setae: bifurcated, angled or swollen. These modifications are known in the basal part of prosomal setae u′, ft′, ft″, d, v, bv, ve, sc and caudal setae h2. We assessed the distribution of atypically shaped setae in Eriophyoidea and showed that they are scattered in different phylogenetic lineages. We hypothesized that the ancestral setae of eriophyoid mites were bifurcated before later simplifying into filiform setae. We also proposed that hypo-furcating setae are a synapomorphy that unites Eriophyoidea with Nematalycidae. We analyzed four new mitochondrial genomes of Leipothrix, the largest genus with bifurcated d, and showed that it is monophyletic and has a unique mitochondrial gene order with translocated trnK. We exclude Cereusacarus juniperensis n. comb. Xue and Yin, 2020 from Leipothrix and transfer five Epitrimerus spp. to Leipothrix: L. aegopodii (Liro 1941) n. comb., L. femoralis (Liro 1941) n. comb., L. geranii (Liro 1941) n. comb., L. ranunculi (Liro 1941) n. comb., and L. triquetra (Meyer 1990) n. comb.
Predatory mites are effective natural enemies of small arthropods, including pest mites and insects, which provide biological control of several crop pests worldwide. The family Phytoseiidae (Acari: ...Mesostigmata) is a diverse group of predators found in cultivated crops and other habitats containing natural vegetation. Although some phytoseiid species are commercialized and widely used in biological control programs, the determination of natural populations and identification of the species is a vital first step in understanding their interactions with the crop, environment, and pests. The citrus crop is a diverse agroecosystem colonized by a variety of pests including mites and warrants an understanding of the complex of predators. We collected predatory mites from multiple citrus groves in Florida, to find and identify species for biological control in citrus crops. The examination of the specimens involved the use of Olympus CX-41 microscope, and drawings were prepared with the help of the attached camera Lucida. Any needed corrections were made using tracing paper, rapidograph pen, and Adobe Photoshop version CS6. Neoseiulus hexaporussp. nov. is described and illustrated as a new species based on its distinct morphology compared with previously described species in paspalivorus group. We also provide a complementary redescription of Neoseiulus mumai (Denmark), including an important diagnostic character of leg chaetotaxy which had led to the description of a new species, Neoseiulus kikuyu Ma, Fan & Zhang. We also provide new illustrations of N. mumai to facilitate its diagnosis.
Over the past century and a half, the taxonomic placement of Eriophyoidea has been in flux. For much of this period, this group has been treated as a subtaxon within Trombidiformes. However, the vast ...majority of recent phylogenetic analyses, including almost all phylogenomic analyses, place this group outside Trombidiformes. The few studies that still place Eriophyoidea within Trombidiformes are likely to be biased by incomplete taxon/gene sampling, long branch attraction, the omission of RNA secondary structure in sequence alignment, and the inclusion of hypervariable expansion-contraction rRNA regions. Based on the agreement among a number of independent analyses that use a range of different datasets (morphology; multiple genes; mitochondrial/whole genomes), Eriophyoidea are almost certain to be closely related to Nematalycidae, a family of vermiform mites within Endeostigmata, a basal acariform grade. Much of the morphological evidence in support of this relationship was apparent after the discovery of Nematalycidae in the middle of the 20th century. However, this evidence has largely been disregarded until very recently, perhaps because of overconfidence in the placement of Eriophyoidea within Trombidiformes. Here, we briefly review and identify a number of biases, both molecular- and morphology-based, that can lead to erroneous reconstructions of the position of Eriophyoidea in the tree of life.
Osperalycus tenerphagus , a new genus and species of Nematalycidae (Acari: Endeostigmata), is described from Ohio, USA, using light microscopy and low-temperature scanning electron microscopy. ...Specimens were extracted from two different loam soils. This genus can be readily distinguished from the other genera of Nematalycidae by the simple setae that line the opisthosoma. The mouthparts are especially distinct in possessing three-segmented palps, an unusual vessel-shaped structure, and rutella that overlap at the midline. The discovery of rutella in this genus and in two other genera indicates that the Nematalycidae can be more confidently assigned to the Endeostigmata (Sarcoptiformes).
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