This species was first described by Edward Meyrick in 1913 using a male specimen collected at Ohakune by George Hudson.[3] Hudson discussed and illustrated this species in his 1928 book The Butterflies and Moths of New Zealand.[4] Alfred Philpott studied A. exsomnis in 1927 examining the genitalia of this species.[5] The male holotype specimen is held at the Natural History Museum, London.[6]
Description
Illustration of male by George Hudson.Male holotype of Atomotricha exsomnis.
Edward Meyrick described this species as follows:
♂. 24 mm. Head and thorax whitish-ochreous, collar dark fuscous. Palpi whitish-ochreous, second joint sprinkled and towards base suffused with fuscous. Abdomen whitish-ochreous, segments yellowish-ochreous towards the base. Forewings elongate, somewhat dilated posteriorly, costa moderately arched, apex obtuse, termen very obliquely rounded; whitish-ochreous, somewhat sprinkled with fuscous and dark fuscous; a suffused dark-fuscous streak running from base of costa to plical stigma; stigmata large, dark fuscous, pale-centred, especially second discal, plical obliquely beyond first discal; a spot of dark-fuscous suffusion on costa above second discal stigma, and a larger spot on costa at ¾, whence an indistinct angulated dark-fuscous line runs to dorsum before tornus: cilia whitish-ochreous, on upper half of termen spotted with fuscous at base. Hindwings whitish-ochreous; a grey discal dot: cilia whitish-ochreous.[3]
This species is similar in appearance to A. isogama but can be distinguished as A. exsomnis has a strongly W-shaped postmedian line and a bolder blotch on the costa at the end of the postmedian line.[7] It has been hypothesised that the adult female of the species may not be brachypterous.[4]
Distribution
This species is endemic to New Zealand.[1] As well as being observed at its type locality of Ohakune, it has been recorded at Mount Ruapehu, Tongariro, Saint Arnaud.[4][8][9] It is regarded as being very local.[4]
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