Agrenia

Börner, 1906

Species Guides

Agrenia is a of springtails (Collembola: Isotomidae) distributed across arctic, , and mountainous regions of the northern hemisphere. The genus was formerly but now contains multiple divided into two groups: the bidenticulata-group (with mucronal seta) and the agilis-group (without mucronal seta). Species exhibit morphological variation in claw structure related to latitude, with some showing sexual and cyclomorphosis.

Pronunciation

How to pronounce Agrenia: /əˈɡreɪniə/

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Identification

The is recognized by apomorphous characters: absence of sublobal hairs on the maxillary outer lobe, presence of on the dens, a long subapical macrochaeta on the inner side of the dens, and presence of a tunica on the unguis. The of the serves as a useful character for separating some . Species groups are distinguished by the presence or absence of a mucronal seta. Claw index and Tibiotarsus/Claw ratio vary geographically and can aid in distinguishing local forms within the A. bidenticulata sensu lato complex.

Habitat

Occurs in arctic, subarctic, , and montane environments. Specific include forest streams in the Appalachian Mountains and glacier surfaces in Washington and Alaska. Buryatian inhabit mountainous areas of East Siberia.

Distribution

Holarctic distribution covering arctic, subarctic, , and mountainous regions of the northern hemisphere. Recorded from North America (Tennessee, North Carolina, New York, Washington, Alaska), East Siberia (Buryatia), Japan, and across the Palearctic including High Arctic and South Siberian mountains.

Behavior

Exhibits sexual (epitoky) and cyclomorphosis in several . Neutralization of male secondary sexual characters has been observed in some reproductive specimens.

Similar Taxa

VertagopusBoth belong to Isotomidae and have been studied together in regional faunas; distinguished by different chaetotaxy patterns and claw .

More Details

Species Groups

Two groups are recognized: the bidenticulata-group (with mucronal seta) and the agilis-group (without mucronal seta). The agilis-group includes four North American species described from forest streams and glaciers.

Morphological Variation

The A. bidenticulata sensu lato complex consists of several local forms differing in Claw index and associated Tibiotarsus/Claw ratio, with these indexes showing dependence on latitude.