Diagnosis. Male recognised by combination of dark head, uniform brownish forewings and distinctly brown hindwing. S. basiguttella can be very similar when the pale pattern is obsolete, but usually a remnant of the basal spot can be observed and in the middle of the wing, S. basiguttella is almost always paler and has always a grey hindwing. S. trojana and bicuspidata superficially resemble samiatella, but have narrow spatulate scales along hindwing dorsum, see also S. karsholti. More problematic are the occasional pale headed S. samiatella, which occur more frequently in southern Europe. These are very similar to S. roborella and less so to S. eberhardi, which usually has darker hindwings.
Females are inseparable from S. atricapitella and can to some extent be confused with S. basiguttella, trojana or zangherii when the forewing is dark.
Male and female genitalia highly characteristic: the male by the low density of cornuti, arranged in three groups, and the female by the long spiny ductus leading to the accessory sac. There is some variability in the female genitalia: this is explained partly by the smaller size of some specimens, but the more globular accessory sac is probably also a result of mating, after which the sac is expanded and the spines are spread out. Also the male genitalia show some variation in shape of valva and length of aedeagus.
Hostplants. Castanea sativa, Quercus ithaburensis subsp. macrolepis (Klimesch 1978), Q. petraea, Q. pubescens, Q. pyrenaica, Q. robur. S. samiatella is the only Stigmella species that is frequently reared from Castanea, the only other Stigmella known with certainty is S. basiguttella.
Leafmine. A gallery with frass first in narrow midline, later in a broad band. Egg reported on leaf underside (Borkowski 1972) or on leaf upperside (Johansson & Nielsen 1990), probably a variable character; eggs usually against a vein; in the few mines studied by us, from which adults were reared, the egg indeed was on leaf underside. Larva yellow, no detailed description because of lack of material (Gustafsson & Van Nieukerken 1990). Mine similar to those of S. ruficapitella, svenssoni and sometimes atricapitella or zangherii. Cocoon: red-brown.
Throughout Europe and Southwest Asia, common almost everywhere, but only a few records from England. No positive records from: Albania, Belarus, Bosnia, Bulgaria, Ireland, Norway, Macedonia, Moldova or Portugal. Known also from Italy, France, Spain and Greece. New (or confirmed) records from Georgia and Russia (also recorded by Shmytova 2002). Highest altitude: 2400 m in Turkey.
Life-history. Bivoltine, larvae in June-early August and September-November, adults April-September, October in southern Europe. In Britain believed to be (partly) univoltine (Emmet 1976b), but in the Netherlands and Sweden clearly bivoltine. The species is remarkably frequently taken at light, in the Netherlands most records are from light collected adults, and very few only of reared adults. The reason may be that samiatella prefers leaves higher up in the canopy, or occurs more frequent in periods when there are few other miners, and thus less collecting activity.
This taxonomic description is based on Van Nieukerken (2003).