Mastodawn

RE: https://mastodon.scot/@kim_harding/115984446339509467

#Sarcoptes #scabiei var. hominis (#Astigmata, Acariformes) is a skin-#parasitic #mite that feeds on human #epidermal cells. Infection typically occurs via adult, mated #females.The mite has #subspecies found on both #domestic and #wild #animals. The #evolutionary direction was via #humanancestors to humans and from there #spreading first to domestic animals and then to wild animals (see ref).
© #StefanFWirth 2026

Reference
R. W. Currier er al. (2012): https://doi.org/10.1111/j.1749-6632.2011.06364.x

Stefan F. Wirth Feb 4

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

Stefan F. Wirth Jan 2

#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

Stefan F. Wirth Nov 3

#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

Stefan F. Wirth Oct 5

#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

Stefan F. Wirth May 29, 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.

Reference:

Stefan F. Wirth about a lemon mite (2024): https://www.fao.org/global-soil-partnership/gsid24/posters/en/

Photos:
© SFWirth Bln, 2006-25

Stefan F. Wirth May 2, 2025

When #animals #carry other organisms: If it is a regular dispersal strategy it can be #phoresy. When phoretic #mites, such as soil mite #Histiostoma sp. (#Astigmata) here, disperse #fungi themselves, this can be hyperphoresy. The mating adult mites in my #SEM carry #macroconidia, presumably of Ascomycota. Adult mites aren't the phoretic stage, thus they can disperse a fungus only within their limited #habitat.
©#StefanFWirth Berlin 2025

Reference
S. F. Wirth (2023)
https://www.fao.org/fileadmin/user_upload/GSP/GSOIL4N/GSOIL4N-Posters/ID_167.pdf

Stefan F. Wirth Feb 13, 2025

Overview of the topic of #muscleattachment and origin points and #muscle #morphology in #Astigmata #mites (#Acariformes). Figs. 1-3 show a view from the #proterosoma towards the #gnathosoma of a mite of the #Acaridae. Fig. 4 shows a female of a #Histiostomatidae mite in the area of #legs 1 and 2 with the associated muscles and muscle attachment points. The already older preparations were critically - point dried before #SEM observations. #acarology #biology
© #StefanFWirth Berlin 2025

Stefan F. Wirth Nov 2, 2024

The #complex #mouthparts of #Acariformes #mites. As an example, here is the #SEM image of a non determined #mite from the #Acaridae (#Astigmata) #cut in the area of the #proterosoma, #perspective towards #gnathosoma from #internally. Visible are the complex #muscles that #move the gnathosoma and partly (left) also the first pair of legs. #Photo from my early postdoc times, re-edited in 2024.
#evolution #Astigmatina

Stefan F. Wirth Oct 29, 2024

This is the first #freeliving #instar of a #mite from the #Histiostomatidae (#Astigmata, #Acariformes) : named the #larva and being characterized by having only #3pairs of #legs, which is a phylogenetically old character. #Specific and thus #apomorphic for Histiostomatidae is that there is a #dorsalpattern of #sclerites, differing between subtaxa. The photo shows the species #Histiostoma sp. (H. feroniarum-complex) from rotting #lemonfruits in Italy (Sorrento).