The caesurifasciella group

Diagnostic characters (Fig. 39): forewing with pattern (with fascia); in male genitalia, uncus semi-rounded distally, gnathos with one caudal process, aedeagus with numerous spine-like cornuti aggregated into a band, manica developed; in female genitalia, accessory sac short and wrinkled, distal half of bursa copulatrix narrow with numerous folds over length of this part; no signa.

Host-plant preferences. Quercus subgenus Cyclobalanopsis (Quercus acuta Thunb., Q. glauca Thunb.) (Fig. 37).

Distribution and taxonomic diversity. Currently includes a single East Palaearctic species (Stigmella caesurifasciella Kemperman & Wilkinson, 1985).

The cornuta group (designated here)

Diagnostic characters (Fig. 40): forewing without pattern (without fascia); in male genitalia, uncus with weakly individualized lobes, gnathos with two partialy reduced caudal processes (and two anterior ones), valva with chitinized apical papilla, tranverse bar of transtilla interrupted medially, aedeagus with extremely large pointed cornuti, juxta present, constricted medially, manica absent; female genitalia unknown.

Leaf-mines combined. Comprise a narrow gallery in the first half and a large blotch in the second half (unique among other Stigmella species feeding on oak).

Host-plant preferences. Subgenus Quercus, section Mesolobatus (Fig. 38).

Distribution and taxonomic diversity. Currently includes a single East Palaearctic species (Stigmella cornuta Rocienė & Stonis, sp. nov. described above).

Note. In male genitalia, the cornuta group exibit some similarity to the non Quercus -feeding betulicola group: apically narrowed valva with a chitinized apical papilla (Fig. 30), interrupted transverse bar of transtilla (Fig. 28), broad lobate vinculum (Fig. 27), and weakly individualized lobes of uncus (Fig. 32). However, the newly designated group clearly differs from the betulicola group (and other Stigmella) by the shape of the extremely large cornuti (Fig. 36), and by the unusual shape of gnathos with partially reduced caudal processes (Fig. 33). The combined leaf-mine (Fig. 20) is also unique among Quercus -feeding Stigmella species (and uncommon or even rare among other Nepticulidae).