Isotoma viridis and Isotoma anglicana are very similar but can be reliably separated (using slide-mounted specimens) by examining the manubrial 'teeth'. Isotoma viridis has a single pair of 'teeth' on the thickened apical edge of the manubrium, whereas Isotoma anglicana has two pairs of manubrial teeth. Isotoma anglicana is more bluish-grey/brown in colour than Isotoma viridis which tends to be more greenish. Another similar species in this complex, Isotoma caerulea, can be distinguished by having a larger macroseta in the outside of the 2nd pair up the manubrium, while Isotoma anglicana has the inner of these 2 macrosetae larger than the outer.
Confirmation requires microscopic proof of presence of two pairs of manubrial teeth.
All year round.
Widespread and fairly frequent in Britain.
Status in Leicestershire and Rutland not known.
Leicestershire & Rutland Map
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