Few words about determining one of most difficult group of European Psychidae - a Dahlicini tribe. This group include small moths (in Palearctic about 50 species). Females are wingless and in few cases are parthenogenetic (there are not known males of species, and female reproduces without copulation).
Determination of species is complicated, due to similarity of each species to another.
In a case of males, there are necessary to study wing venation (presence of additional cells, how many veins goes from median cell, are those stalked or not). Moreover very helpful is "genital index" (ratio of length of aedeagus to lenth of valve - see photo) and shape of forewing scales which are grouped in 6 types from narrow to wide - see photo. Further, presence of tibial thorn (epiphysis) - see photo, what is very small and is hidden behind scales covering leg (this is primary feature to distinguish Siederia genus from Dahlica). Shape and pattern of wings are in general just for complementation.
In a case of females, there is necessary to study a shape of head plate (see photo), and shape of genital plate, and surface of pupal exuvia (small thorns).
There are many different features which are helpful and always they need to be taken into concideration together.
(Sorry for poor photo's quality)
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Female's pupa head plate |
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Male's genital index |
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Male's forewing scales |
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Male's foreleg with tibial thorn (epiphysis) |