Ascidae

Voigts & Oudemans, 1905

Ascidae is a of predatory in the Mesostigmata. Members occupy diverse including soil, litter, bark, and freshwater margins. Many are phoretic, dispersing on larger such as and . The family was historically broader, with Blattisociidae and Melicharidae now treated as separate families based on morphological distinctions.

Pronunciation

How to pronounce Ascidae: /ˈæsɪdiː/

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Identification

Ascidae can be distinguished from the morphologically similar Blattisociidae and Melicharidae by the combination of: broadly connected peritrematic and exopodal shields beside IV, presence of setiform pilus dentilis on the fixed cheliceral digit, and the typical position of sternal lyrifissures. The family Asca lacks the diagnostic character typical of its in the unusual A. acornis, which occurs in in the southern United States.

Appearance

Ascidae are mesostigmatic with the following diagnostic features: st4 usually positioned on unsclerotised ; peritrematic shield broadly connected to exopodal shield beside IV; fixed cheliceral digit with setiform pilus dentilis; movable cheliceral digit usually with two ; sternal shield bearing three pairs of lyrifissures with the third pair typically on the margin; genital shield to convex posteriorly (tapering in some Antennoseius); shield bearing only circumanal , or ventrianal shield bearing up to seven additional pairs of setae; spermathecal apparatus of laelapid .

Habitat

Ascidae occupy multiple : epedaphic hunt on soil surface in litter layers; others occur under bark of dead trees, on small mammals, and in nests of birds and mammals. Some species inhabit wet plants, detritus, and the water surface of marginal freshwater habitats where they walk on the surface film. species occur in vegetation. Soil-dwelling species occupy coastal maritime and inner salty grasslands, forest and orchard soil-litter, and moss.

Distribution

Ascidae occur globally across many countries and regions. The highest numbers of , species, and occur in the Palearctic, which is considered the 's region of origin. The most speciose genus, Asca, has the most species in the Neotropical and Oriental regions. Documented occurrences include Australia, Russia, Iran, Kazakhstan, Eastern Ukraine, North America, and Svalbard.

Diet

Ascidae are predatory. Soil-dwelling on small , particularly (), and exhibit nematophagy (consumption of nematodes). Aquatic species on water surfaces feed on floating masses of nematocerous including mosquitoes. Blattisocius keegani consumes eggs of stored grain pests including and ; approximately three Cryptolestes turcicus eggs are required to rear one mite to adulthood, and females consuming one egg daily can oviposit. Arctoseius species consume eggs and of mushroom flies.

Life Cycle

The comprises , , , , and stages. Each stage lasts days. Total lifespan averages 27 days in Arctoseius semiscissus and 19 days in Proctolaelaps deleoni. At 80°F and 70-75% , Blattisocius keegani completes its life cycle in 6-7 days.

Behavior

is common: Arctoseius ride on of mushroom Lycoriella auripila; aquatic species are phoretic on adult ; Anystipalpus and Antennoseius species are phoretic on . Up to 72 specimens have been observed on a single . Simultaneous phoresy (synphoresy) of multiple mite on the same beetle occurs. Mite associations appear weakly tied to specific beetle and more strongly related to beetle size group and .

Ecological Role

Ascidae function as in soil, litter, and other microhabitats, regulating of , nematodes, and other small . Some are subcortical associates of . Aquatic species may influence mosquito populations by consuming masses.

Human Relevance

Blattisocius keegani is a agent for stored grain pests, preying on of and that infest stored grains. The finite rate of increase is 3.33 female offspring per female per week at 80°F and 70-75% .

Similar Taxa

BlattisociidaeFormerly included within Ascidae; separated based on morphological distinctions in shield connections and cheliceral structures
MelicharidaeFormerly included within Ascidae; distinguished by morphological characters of the peritrematic shield and cheliceral

More Details

Taxonomic history

Blattisociidae and Melicharidae were formerly included within Ascidae but are now recognized as separate . Protogamasellopsis has been transferred to Rhodacaridae, Tangarorellus to an unspecified family in Rhodacaroidea, and Lindquistoseius to Ologamasidae. Orolaelaps was removed from synonymy with Melichares.

Notable genera

Asca is the most speciose , with highest diversity in Neotropical and Oriental regions. Other significant genera include Arctoseius, Antennoseius, Anystipalpus, Blattisocius, Lasioseius, Proctolaelaps, and Zerconopsis. At least 15 genera occur in Australia, with 14 genera and 26 treated in recent revisions.