Stigmella caesurifasciella

Stonis, Jonas R., Diškus, Arūnas, Remeikis, Andrius, Navickaitė, Asta & Rocienė, Agnė, 2013, Description of new species of oak leaf-miners (Lepidoptera: Nepticulidae), with notes on the species groups of Stigmella Schrank associated with Quercus as a host-plant, Zootaxa 3737 (3), pp. 201-222 : 210-218

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 ).

Figures

FIGURE 37. Feeding preferences of the species groups of Stigmella associated with Quercus as a host-plant. Some species of the ruficapitella group may feed on more than one host-plant, thus the total percentage of host use for the group exceeds 100 %.

FIGURE 38. Feeding preferences of the saginella, the cornuta and the hemargyrella groups. Some species of the saginella group may feed on more than one host-plant, thus the total percentage of host use for the group exceeds 100 %.

FIGURES 39 – 41. Diagnostic characters of the caesurifasciella, the cornuta and the saginella species groups.

FIGURES 25 – 30. Stigmella cornuta Rocienė & Stonis, sp. nov., morphology. 25, male adult, holotype; 26, same, forewing, artist reconstruction, scale bar 1 mm; 27, male genitalia, holotype, gen. slide no. AG 419, scale bar 100 µm; 28, same, transtilla; 29, same, vinculum (constricted laterally); 30, valva and juxta (the arrow indicates a chitinized apical papilla). Scale bar 50 µm.

FIGURES 31 – 36. Stigmella cornuta Rocienė & Stonis, sp. nov., details of male genitalia, holotype, gen. slide no. AG 419. 31, fragment with uncus and gnathos; 32, uncus, reconstruction; 33, gnathos, reconstruction; 34, 35, cornuti; 36, same, reconstruction. Scale bar 50 µm.

FIGURES 18 – 24. Stigmella cornuta Rocienė & Stonis, sp. nov., bionomics. 18, habitat, deciduous broad-leaved forests in NE China, Huairou District, 40 ° 25 ' 56 '' N, 116 ° 33 ' 20 '' E; 19, cocoon, scale bar 1 mm; 20 – 24, leaf-mines on Quercus dentata Thunb., Fagaceae (arrows indicate the narrow part of the mines: a gallery completely filled with black-green or brownish frass).