Hans Klompen

Phoresy, a common dispersal strategy among arthropods, involves complex relationships between hosts and symbionts that influence ecological dynamics. Investigating the structure of phoretic mite communities and their population fluctuations is particularly relevant for widely distributed agricultural pests, such as the coconut palm weevil, Rhynchophorus palmarum . This study investigated the community of phoretic mites associated with R. palmarum in its native Neotropical range, aiming to characterize population patterns, evaluate the influence of host attributes, and analyze interspecific dynamics. A total of 14 mite taxa were recorded, all exhibiting high prevalence and strong aggregation. The mite Centrouropoda cf. brasiliana stood out as the dominant species, with individual loads exceeding 2,800 mites per beetle. Although host sex and body size did not affect total phoretic load, body size selectively influenced the abundance of certain taxa ( Lasioseius sp., Macrocheles mammifer , Gamasina sp. 1, and Crenamargo binuseta ). The temporal variation of C. cf. brasiliana were negatively modulated by C. binuseta and Rhynchopolipus rhynchophori , suggesting mechanisms of competitive exclusion or microhabitat partitioning. These findings highlight a complex community in which biotic interactions play a central role in structuring the phoretic acarifauna of R. palmarum , emphasizing the need for further investigations into the functional effects of these relationships.

Significant progress has been made in the understanding of family-level relationships among most major lineages of Mesostigmata. An exception to this is Uropodina, a lineage with a problematic classification and incomplete species descriptions. While recent efforts have been made in cataloging names of varying taxonomic levels, a stable and concrete classification system is still lacking. This is mainly due to the absence of a robust phylogenetic analysis for the group. Our study aims to address this by inferring the phylogeny of Uropodina using molecular data derived from the mitochondrial genome. Our taxon sampling included representatives of most biogeographic realms and a wide variety of habitats, covering 28 of the 31 recognized uropodine families. We attempted to assemble mitochondrial genomes from 91 samples sequenced using a low coverage whole genome skimming approach. Resulting assemblies were annotated to identify and extract sequences of the 37 mitochondrial genes. For phylogenetic analysis, we only included data from the 13 protein coding genes of the mitochondria. Tree inference using maximum likelihood and Bayesian methods were conducted on datasets that included varying taxonomic and gene coverage. Of the 91 samples sequenced, we assembled complete mitogenomes for 48 species and recovered fragments for all except 2 of the remaining samples. Complete mitogenome sizes ranged from 14,291-15,804 base pairs with relatively low GC content across all samples. Genes generally followed the known order of uropodines. We identified three main rearrangements characterized by the position of tRNAs C and P, as well as a few highly divergent gene orders. Maximum Likelihood and Bayesian trees showed strong support for monophyly of Uropodina, including Microgyniidae but not Protodinychidae (the position of Diarthrophallidae could not be established due to insufficient sequencing results). Resulting tree topologies suggest up to seven major groupings potentially representing superfamilies. These include a well-supported monophyletic Uropodoidea (sensu stricto) and a previously unrecognized clade of predominantly tropical distribution. This tropical clade included a subset of the problematic family Urodinychidae which appears to be polyphyletic. Lastly, the recognition of “higher Uropodina” characterized by the presence of a sclerotized node in the chelicera received no consistent support. Insights from our mitochondrial phylogenomic study are inconsistent with the current classification of Uropodina. However, a more robust revision of higher-level classification of the group will require integration of nuclear genomic and morphological datasets.

Uropodina form a very diverse lineage with global distribution. Unfortunately, there is still little agreement on classification within the lineage, with different schools of thought emphasizing different (morphology based) character systems. One solution is to discard morphology and develop phylogenies and classifications based entirely on molecular data, but this may be excessive. In the current project, morphology and molecular data are integrated in a total evidence analysis. The main questions are to what degree results from analyses using morphology only are consistent with the combined analyses, and whether the addition of morphology to the combined analyses provides added value (e.g. better or worse resolution, better or worse support.) Two sets of morphology-based character matrices were constructed, one based on vouchers from DNA extractions (199 taxa), and another, taxonomically broader one, based on available literature data (215 taxa). Taxa were coded for all morphological characters (170) that could be coded in a consistent way. This includes traditional characters and some newly developed characters based on micro-CT scans. This data set was combined with DNA sequence data for nuclear rDNA and mitogenomes. This shows that morphology only are consistent with combined analyses. Given this, we expect that the addition of morphology may provide added support for some of the newly recognized lineages in Uropodina.

Persicolaelaps Kazemi andamp; Beaulieu was originally described as a monotypic genus of Laelapidae from the Hyrcanian broadleaf forests of northern Iran. The genus occurs in northern Iran and eastern North America, representing a striking and poorly understood biogeographic disjunction. What makes this record remarkable is not only morphological concordance but distributional discontinuity. The absence of European records raises critical questions. Did Pleistocene glaciations eliminate suitable refugial habitats across much of Europe? Have repeated climatic oscillations fragmented populations in intermediate regions? Alternatively, has long-term anthropogenic reduction of old-growth, deadwood-rich forests contributed to the regional disappearance or extreme rarity of such specialized taxa? Persicolaelaps hallidayi Kazemi andamp; Beaulieu was originally described from rotten wood (holotype) and litter (two paratypes) in the Hyrcanian broadleaf forests of northern Iran. The North American record of the genus is based on a single museum specimen collected in 1975 from a coniferous forest in Connecticut, recovered from pine litter and rotten wood, representing a comparable late-stage decayed wood microhabitat. The genus is defined by a rare combination of structural characters, most notably six setae on trochanter IV, together with an anal shield incorporating JV3 and small sclerotized platelets surrounding the gnathosomal region. The Connecticut specimen exhibits the primary diagnostic features of Persicolaelaps despite minor morphological differences, supporting its placement within the genus. The Iranian and North American records are separated by a geographic distance, with no confirmed occurrences in Europe or western Asia, while European mite faunas are relatively well studied. Both records are consistently associated with late-stage decayed wood, particularly heavily decomposed, powdery substrates rather than superficial bark habitats, suggesting specialization to a narrowly defined microhabitat. The distributional pattern recalls well-known Hyrcanian–Appalachian floristic parallels, in which relict temperate forest lineages occur in northern Iran and eastern North America but are absent or rare in intervening regions. Similar fragmented Holarctic patterns have been documented in specialized saproxylic insects associated with advanced wood decay, indicating that microhabitat specialization can obscure broader biogeographic structure. Such cases underscore the importance of integrating taxonomy and biogeography in revealing hidden distributional histories. This remarkable disjunction suggests that our current understanding of forest microfaunal connectivity and persistence across the Holarctic remains incomplete. Focused sampling of late-stage decayed wood across temperate forests will be essential to test these hypotheses and clarify the evolutionary and biogeographic significance of this lineage.

The taxonomic position of Africoseiulella is reviewed based on a new species associated with Acheta domesticus (L.) (Orthoptera: Gryllidae) collected in northern Iran and type specimens of A. flechtmanni Kreiter, originally collected from an unidentified low-growing weed in Tunisia, and A. sedishazlensis El-Banhawy, Nasr & Ramadan. Africoseiulella hajiqanbari sp. nov. is described along with brief complementary descriptions of A. flechtmanni and A. sedishazlensis, and an updated diagnosis of the genus Africoseiulella. The genus is unique within Gamasina by the absence of setae al3 and pl3 on tarsi II–IV, as well as seta ad2 on tarsus IV. It also features a stout, unbranched palp tarsus apotele and a large membranous flap fused to a sickle-shaped movable cheliceral digit. Africoseiulella was previously classified within Phytoseiidae; however, a comparative analysis revealed significant differences with Phytoseiidae, Blattisociidae, Podocinidae, and Treatiinae (as redefined in this paper). Therefore, Africoseiulella is placed in its own family (Africoseiulellidae fam. nov.).

Ant nests are biodiversity hot spots, concentrating resources from a wide area that can be exploited by other organisms, known as myrmecophiles. The mite order Mesostigmata includes a wide range of lineages that have become myrmecophiles with many species reliant on ant nests for at least part of their development. The nature of the associations is quite variable, including predators of smaller arthropods in the nest (close to the ancestral lifestyle of these mites), scavengers, kleptoparasites, parasites, and parasitoids. A few mite species show extreme modifications of morphological and/or developmental patterns, others show almost none. Some host specificity is common but one-on-one host specialization is rare or poorly tested. Phoresy on the ants is common, but the target ant caste varies with the goal of phoresy. In general, the diversity of mesostigmatid mites in the nest of a given ant species is affected by habitat conditions along with a range of life history characteristics of the ants, including factors such as body size, colony size, colony founding mode, social parasitism, and nest density. Unfortunately, the life history of the majority of mites associated with ants is still unknown.

Cingulacarus Elsen is a monotypic genus of Trigynaspida based on C. gangeticus Elsen, collected from the scarabaeid beetle Scarabaeus gangeticus (Castelnau) (Col., Scarabaeidae) in the Democratic Republic of the Congo. Herein, a second species of the genus, C. kermanensis sp. nov. is described based on female and male specimens collected in southeastern Iran, in association with Oryctes elegans L. (Col., Scarabaeidae). The diagnosis of the genus Cingulacarus is revised, with a discussion of the impact on current generic keys for the family Diplogyniidae, and a proposal to eliminate the current subfamilial classification within that family.

The genera of Heterozerconoidea are revised based on a species-level analysis of relationships in the group. The family Discozerconidae in its current state may be paraphyletic. Diagnoses for the genera are updated, and a catalog of all described species is provided. As part of this re-analysis two new genera, Amyzozercon and Ecuazercon, and four new species are described, and a key to the genera is provided. Possible evolutionary implications of the proposed set of relationships in terms of biogeography and the evolution of podospermy are discussed.

: Amblyomma americanum , a known vector of multiple tick-borne pathogens, has expanded its geographic distribution across the United States in the past decades. Tick microbiomes may play a role shaping their host’s life history and vectorial capacity. Bacterial communities associated with A. americanum may reflect, or enable, geographic expansion and studying the microbiota will improve understanding of tick- borne disease ecology. We examined the microbiota structure of 189 adult ticks collected in four regions encompassing their historical and current geographic distribution. Both geographic region of origin and sex were significant predictors of alpha diversity. As in other tick models, within-sample diversity was low and uneven given the presence of dominant endosymbionts. Beta diversity analyses revealed that bacterial profiles of ticks of both sexes collected in the West were significantly different from those of the Historic range. Biomarkers were identified for all regions except the historical range. In addition, Bray-Curtis dissimilarities overall increased with distance between sites. Relative quantification of ecological processes showed that, for females and males, respectively, drift and dispersal limitation were the primary drivers of community assembly. Collectively, our findings highlight how microbiota structural variance discriminates the western-expanded populations of A. americanum ticks from the Historical range. Spatial autocorrelation, and particularly the detection of non- selective ecological processes, are indicative of geographic isolation. Our conclusions demonstrate the value of synergistic analysis of biogeographic and microbial ecology data in investigating range expansion in A. americanum and potentially other tick vectors as well. Importance: The incidence of tick-borne diseases is on the rise worldwide, including in the United States. This increase in cases is in large part due to the geographic expansion of tick vectors. Among them is the Lone Star tick, Amblyomma americanum , and understanding the factors driving its recent expansion is important for risk assessment and tick population control. Climate change and human activities have previously been posited to be main driving forces for their expansion. New sources of relevant biological data can further our understanding of this phenomenon. Microbial communities associated with ticks include bacteria that affect pathogen transmission and tick behaviors. Here, we investigated whether bacterial community and geographic location data could be combined to better understand the expansion of A. americanum populations. It’s not clear whether differences in the microbiota are reflective of or facilitating expansion, but our findings suggest this approach is promising and warrants further investigation.

Primary and secondary sexual characters of Mesostigmata are often used in species descriptions and phylogenetic analyses. The use of these characters has been focused almost exclusively on external structures such as the male chelicera and genital plates, while internal structures have only been utilized for lightly sclerotized species.