Callisto sp.

(Figs 11 B–C)

Material examined. Russia: PK, Gornotaezhnoe, MTS, 43.69N, 132.15E, 152 m alt., Malus sp., 24.VII.2016, 1 larva, NK548 , MK 403677, deposited in INRA.

Leaf mine. Blotch mine between two secondary veins in parenchyma, with a preceding short (not always visible) epidermal tunnel, with a central frass line, on the lower or upper side of the leaf (Fig. 11B). The blotch is flat but soon gets tentiform-like (similar to Phyllonorycter) due to silk deposited by the larva in the mine that dries and shrinks the mine causing 1–2 wrinkles on the epidermis covering mine. The larva vacates the mine through the hole in the lower epidermis, in the corner of the mine (Fig. 11B), and continues living in a shelter, under the leaf margin folded downwards, on the same or neighboring leaf (Fig. 11C). When about one third of a half parenchyma layer is eaten out in the shelter, the larva creates a new shelter (Fig. 11C).

Trophic specialization. Monophagous on Malus sp. ( Rosaceae).

Distribution. Russia: RFE—PK.

Remarks. BIN of unknown species—BOLD: ADF4428. Callisto sp. does not match any known Callisto species in BOLD or NCBI. Overall, in the Palearctic, three Callisto species are known on Rosaceae: C. albicinctella Kuznetzov (RFE; host: Prunus), C. denticulella (Thunberg) (Europe; Rosaceae, including Malus), and C. insperatella (Nickerl) (Europe, RFE; host: Rosaceae, including Prunus) (De Prins & De Prins 2018). C. denticulella (DNA barcodes from Canada and France) is the closest relative to our Callisto sp., with minimum interspecific divergence 2.2% (Table 2). The distance from C. insperatella sampled for the fist time in RFE reaches 3.7% and from C. insperatella collected in Poland—4.3% (Table 2). There are no DNA barcode sequences of C. albicinctella in the genetic databases. C. albicinctella is known to develop on Prunus (Kuznetzov 1979b); no record of this species from Malus is known. If the latter species remains trophically linked only to Prunus, our Callisto sp. may represent a new species.