Stigmella prunetorum, Stigmella
Diagnosis. Small size, black head, shining brass-coloured base of forewing and, in the male, dark hindwings with short androconial scales along dorsum separate prunetorum from all other species with fascia. The male genitalia can be recognized by the combination of very broad uncus, undivided valva and aedeagus with numerous small spines.
The clearly visible, double-serrated structure in ductus spermathecae is unique in the European Stigmella.
Male. Wingspan: 4.5-4.7 mm. Head: frontal tuft fuscous; scape and collar silvery white, often with yellowish tinge; collar usually rather large; male antenna slightly less than half length of forewing. Thorax bronze to greenish bronze. Forewing: proximal third or quarter shining bronze to brassy, often with purple tinge at costa and base; quarter proximal to fascia purple fuscous; fascia postmedial, pale golden; fascia almost straight and usually rather broad; distal to fascia purple fuscous; terminal cilia concolorous or slightly paler than wing-apex. Hindwing: in male dark greyish brown with dark brown androconial scales on dorsum, extending over fringe to, at most, one-fourth length of fringe.
Female. Wingspan: 4.3-4.6 mm. Antenna distinctly shorter than half length of forewing. Hindwing: greyish brown, without androconial scales. Otherwise similar to male.
Male genitalia. Vinculum with short posterior plate and distinctly excavated anterior extension; lateral corners pointed. Uncus short and broad, posterior corners slightly produced; hind margin slightly concave; margins distinctly sclerotized forming a prominent X-shaped structure. Tegumen: a very narrow band. Gnathos with long and rather
thin horizontal element; horns long and narrow; anterior processes small but distinct. Valva slender, slightly arcuate and without division. Transtilla with long sublateral processes; tip of process slightly thickened. Juxta almost triangular, anteriorly tapering into small, more sclerotized band. Aedeagus three-fourth to four-fifth as long as genital capsule; vesica with many small spines.
Female genitalia. Bursa copulatrix approximately half length of abdomen and without pectinations. Vestibulum long and wide. Accessory sac complex, consisting of several compartments: principal sac large, arcuate with two to three additional spined sacs; ductus spermathecae a long, arcuate and heavily sclerotized canal with distinctly serrated edges. Reticulate field at base of accessory sac large and distinct. Corpus bursae rounded, without pectinations. Posterior apophyses thin and distinctly longer than anterior apophyses. Tergum VIII with medial sclerotized pointed or bipointed process.
Host plants: Prunus spinosa, P. domestica and occasionally P. avium, P. cocomilia and P. cerasus. Egg: on the underside, often close to a rib but sometimes between ribs or at margin. Larva: dull pale green; head slightly darker. Mine: first part of mine forms 5-10 circles or semicircles around the egg site, followed by straighter track that often runs along the leaf margin. Frass coiled, usually filling the mine completely. Cocoon: brown to red-brown.
There are no confirmed records from Jutland but reported from all other districts in Denmark. In southern Sweden to Vg. and Sdm. in the north. No records from Finland and Norway. - Common and widely distributed in all C. European countries and The British Isles, Italy, Yugoslavia, Greece and S.W. U.S.S.R.
Voltinism: two generations per year.
Description based on Johansson and Nielsen (1990)