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Dysstroma Hübner 

Type species: russata Denis & Schiffermüller = truncata Hufnagel, Europe.

Synonym: Polyphasia Stephens (type species centumnotata Schulze = truncata Hufnagel, Europe). 

It is still an open question as to whether Dysstroma should be placed in synonymy with Chloroclysta Hübner (type species miata Linnaeus, Europe). The genitalic morphology of the two genera is similar, with rather rounded, unmodified valves, and well developed anellus lobes. The uncus is long, slender acute, the saccus broad. The aedeagus vesica contains a conspicuous mass of cornuti. In typical Chloroclysta the setae on the anellus lobes are distinctly spatulate (Pierce, 1914), but usually unmodified in Dysstroma. In the females, the signum of Dysstroma is ovate, scobinate, but ribbon-like or absent in Chloroclysta (Pierce). Yazaki (1994, 1995) treats Dysstroma as distinct, as does Choi (in press). The forewing facies is distinctive, particularly the strongly lunulate nature of the sinuous postmedial. The hindwings are more or less uniform, paler than the forewing. The male antennae are filiform, and the abdomen lacks coremata. 

The larvae are slender, green, with a slight lateral ridge running longitudinally (illustrations in Sugi (1987)). They lie fully stretched on host foliage but may rest with the head end scrolled under the body (illustration in Sugi).

European species feed on Betulaceae, Ericaceae, Rosaceae and Salicaceae (Allan, 1949); in Japan also several ericaceous hosts have been noted (Sugi, 1987) 

The genus is distributed through the Holarctic, but has its centre of diversity in the N.E. Himalaya and western China. Several species are endemic to mountainous regions of the Oriental tropics, their distribution correlating well with the Sumatran and Luzon tracks recognised by van Steenis (1964) for montane plants (Holloway, 1970, 1986).

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