A striking #character of adult #mites in #Histiostomatidae (#Astigmata) is a highly #sclerotized area on the upper surface of #proterosoma. Its #latticelike #structure forms a #taxonomically relevant #symmetrical #pattern of windows, for which I introduced a #nomenclature in my PhD thesis. This area is a site of #muscleorigins (see #SEM section through a bigger specimen of #Acaridae).
©#StefanFWirth 2026
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#pics
©S.F. Wirth edit 2026
#Mouthparts in #mites of the #Acariformes are usually normal shaped as typical for #arachnids. The #chelicerae are the feeding organs consisting of digitus fixus and d. mobilis. #Pedipalps have sensing functions with different kinds of #sensoryorgans. In #Histiostomatidae (#Astigmata) the whole #gnathosoma is modified into a complex #filterfeeding organ that creates an #underpressure on #food surfaces.
© #StefanFWirth Berlin 2026
Reference
S. F. Wirth (2023)
https://www.fao.org/fileadmin/user_upload/GSP/GSOIL4N/GSOIL4N-Posters/ID_167.pdf
#Mites of the #Histiostomatidae live in #darkness in their #ephemeral #microhabitats. The distinctive deutonymphs are the #dispersal stage, being transported by insects. #Adults, however, live freely and #communicate via complex #olfactorysignals. An important #glandularcomplex is located on the dorsal body side. I participated in a study about the #geranial-rich glandular #secretions (2012).
© #StefanFWirth 24 Dec. 2025
Ref
https://doi.org/10.1080/01647954.2012.662247
©S.F. Wirth, Histiostoma sp.
#Mites of the #Histiostomatidae (#Astigmata) not only have highly #modified #mouthparts (see photo) that form a #filterfeeding organ, but their #copulatoryposition is also an #evolutionary #modification. Other Astigmata mate back-to-back, while Histiostomatidae have the male riding on top of the female, head over head. See here the dorsal #copulationopening of a #female of #Histiostoma sp..
©#StefanFWirth 2025
Further reading S.F. Wirth ( 2024)
https://www.fao.org/global-soil-partnership/gsid24/posters/en/
SEMphotos ©S.F. Wirth
In my new YouTube #video, I tell the #hypothetical story of a #Histiostomatidae #mite that lived its #lifehistory in the #dung heap of the #dinosaur #Edmontosaurus #annectens during the Late #Cretaceous. It developed #fungivorously within the dung and, when conditions deteriorated, was #transported by #flies to a new habitat (phoresis). All images and footage created with #AI assistance, except photos of free-living mites.
© #StefanFWirth 2025
Video
https://youtu.be/gzv-TZmU5G4?si=zrTLfrC96k3KEGqr
Pics
© S.F. Wirth
#Mites of the #Histiostomatidae (#Astigmata, #Acariformes) are adapted due to #evolution to form #species with #small sizes of about 200-400 micrometers in adults. Their thin #cuticles and modified #filterfeeding #mouthparts for #fungus-bacterial #food intake allowed their #radiation within shortliving moist and bacteria/fungus rich habitats.
©#StefanFWirth October 2025,
Photos
Females of #Histiostoma sp., from #sapropel #mud around gravel pit ponds, #Berlin #Grunewald, 2019, New edit 2025
In #Astigmata #mites #chemosensitive/#tactile interactions take precedence over #visualsenses. #Histiostomatidae (here, #Histiostoma sp., H. feroniarum complex, ex #rottinglemons, #Italy) communicate using various #pheromones/allomones produced by the #opisthonotal #glands. See here a #glandularopening on the upper hindbody #(hysterosoma) of a #female, #SEM.
© #StefanFWirth, 2025
Reference:
Stefan F. Wirth about a lemon mite (2024): https://www.fao.org/global-soil-partnership/gsid24/posters/en/
Photos:
© SFWirth Bln, 2006-25
The #duskyant, #Formica #fusca (#Myrmicinae), is a ground-dwelling #ant with #earthnests in warmer habitats, widespread in #CentralEurope and extending across the western #Palearctic. The nests are #polygynous (severely active #queens). Like many ant species, this one also carries #phoretic organisms on its body, e.g., #mites of the #Histiostomatidae. #biodiversity #insects #Hymenoptera
© #StefanFWirth, #Berlin May 2025
Artistic Photo:
#Worker of F. fusca Berlin, May 2025, © S.F. Wirth
#Histiostomatidae #mites phoretically attach arthropods, having e.g. these #apomorphies (newly evolved features): #filtermouth in free stages and forward-facing #legs 3,4 of #deutonymphs, supporting #attaching/#detaching #host. #Images = my current #research
© #StefanFWirth 2025
Related papers
S. F. Wirth 2016
https://doi.org/10.21684/0132-8077-2016-24-2-97-111
S. F. Wirth 2023, pp 102-103
https://doi.org/10.4060/cc6728en
#Photos
1) sideview mouth adult H. sp ex tree stump (2022) 2) deutonymph B. #sibirica (2016) © S. F. W.
Bonomoia sibirica sp. n. was reared under laboratory conditions in the original samples of bark beetle galleries together with several specimens of the Dendroctonus micans (Coleoptera: Scolytinae) beetle. Two types of samples were examined: the beetles taken from their hibernating galleries with some original substrate sticking to their bodies and the original bark pieces with corresponding soil from those galleries. Some mite protonymphs and tritonymphs appeared only in the soil remains on the bark beetle bodies, while the beetles themselves lacked mite deutonymphs; the collected bark contained also no mites. It is concluded that B. sibirica sp. n. needs to be in close contact with its carriers for a successful development. Since no males were found in the cultures of B. sibirica, it is assumed that these mites can reproduce by thelytoky. Under laboratory conditions, the deutonymphs preferred attaching to imagines of D. micans along the entire dorsal side of the elytrae. Furthermore, B. sibirica is one of a few Bonomoia species (including the species previously referred to genus Probonomoia) known from both, immatures and adults. Based on the morphological features of deutonymphs and adult females, B. sibirica sp. n. is assumed to be a sister species of B. certa. It is discussed whether the known Bonomoia species, found in association with beetles of the taxon Scolytinae, might represent a subclade within Bonomoia. DOI: 10.21684/0132-8077-2016-24-2-97-111
Stefan F. Wirth