Diagnosis. Male specimens of zelleriella and S. benanderella are very similar but the latter is usually smaller, more coarsely scaled and lacks purplish lustre on forewing apex. The genitalia are easily separable by the shape of uncus and valvae. Females of zelleriella, S. benanderella and S. floslactella are similarly coloured; benanderella can be separated from zelleriella by smaller size and blunt abdominal tip; floslactella is more coarsely scaled and has more contrasting wing pattern with blackish wing apex and contrasting yellowish white cilia. The shape of the apophyses provide good separating characters; long and broad in zelleriella, long and very slender in floslactella and short in benanderella.
Male. Wingspan: 5.2-5.8 mm. Head: frontal tuft grey-brown, sometimes mixed with yellow; collar yellowish white; scape white to pale grey; antenna three fifths of forewing length, dark grey. Thorax concolorous with base of forewing. Forewing: area proximal to fascia shining pale to dark grey-brown with bronze reflections; fascia absent or, if present, ill- defined greyish; distal to fascia slightly darker, brownish with more or less distinct purplish lustre; terminal cilia yellowish grey beyond an ill-defined line of dark-tipped scales, paler grey at tips. Hindwing and cilia pale yellowish grey. Abdomen dark grey with small grey anal tufts.
Female. Wingspan: 4.5-6.2 mm. Frontal tuft varying from yellowish white to ochreous or orange, sometimes mixed with brown but lighter than in male; collar and scape yellowish white; antenna half length of forewing. Forewing area proximal to fascia yellowish bronze to pale yellow; fascia ill-defined, slightly paler than basal half of forewing; distal to fascia distinctly darker than basal part, brownish to dark grey with purplish lustre. Abdomen grey with prominent, long and pointed ovipositor; anal tufts pale grey, as long as ovipositor. Male genitalia. Vinculum with shallow to moderately deep anterior emargination. Uncus almost square at tip, medially split into two lobes, each lobe slightly emarginate. Gnathos with prominent basal plate; horns long and parallel, well separated at base; lateral arms and anterior processes distinct and well sclerotized. Valva long, parallel- sided, posteriorly rounded with two very short inward-curved points. Transtilla with short, broad transverse bar and triangular sublateral processes. Aedeagus distinctly shorter than genital capsule with 5 to 6 unilaterally more sclerotized cornuti and a cluster of 5 to 9 spines of varying length; number of cornuti and spines 10-15, usually 12. Female genitalia. Corpus bursae with broad and conspicuous band of scallop-like chitin plates and a few, very fine and indistinct pectinations; posterior part (ductus bursae) narrow, strongly folded. Ductus spermathecae with fine internal spines. Apophyses very long, anteriores broad, medially fused; anterior processes broad, inward-curved; posterior apophyses almost as long as anteriores, slender. Anal tufts two thirds length of apophyses. Ovipositor very long, tip pointed.
Host plants: Salix repens and S. arenaria, in northern Sweden and Finland mainly on Salix lapponum and possibly other Salix species. Egg: is laid on underside of leaf, close to midrib or leaf margin. Larva: yellow to brownish yellow. Mine : starts as a short gallery, often following leaf-margin and terminating in a blotch occupying half the leaf, more in small leaves; frass black almost completely filling the gallery; irregularly dispersed in the blotch. Vacated mines stain black. Mines probably not reliably separable from benanderella mines and sometimes occurring together; however, mines with the egg on the leaf upperside always belong to benanderella.
Denmark: NEZ and several localities in Jutland; Norway: Sti.; S. Sweden: Gtl., Hall. and S. Finland; widely distributed in northern Finland and Sweden, south to Idre in Dlr. - Along the coast of The Netherlands, Belgium, Poland and S. England, probably also in N. Germany.
Voltinism: in Denmark and the Netherlands bivoltine. Larvae found from late June to first half of July and from late September to early October; in northern Scandinavia in August. Outside Fennoscandia the species is almost confined to coastal sand dunes.
Description based on Johansson and Nielsen (1990)