Stigmella crassifoliae Remeikis & Stonis, sp. nov.

Stigmella nigriverticella (Chambers, 1875) [partim] in Stonis et al. 2013b: 2 –4; figs 7–9, 30, 32–34, 46–54 (see Remarks). (Figs 1–21)

Type material. Holotype: ♂, GUATEMALA, Quetzaltenango, 14°47'27"N, 91°32'09"W, mining larvae on Quercus crassifolia, elevation 2500 m, 08.ii.2012, field card no. 5120, LT-GT Scientific Expedition, genitalia slide no. RA 490♂ (LEU, with final deposition in ZMUC). Paratypes: 5♂, 13♀, same locality and date, mining larvae on Quercus crassifolia and Q. crispipilis, genitalia slides nos RA483♀, RA484♀, RA 485♂, RA 486♂, RA487♀, RA 488♂ (LEU, with final deposition in ZMUC).

Diagnosis. The new species belongs to the Stigmella saginella group (for the characters of the group see Stonis et al. 2013a) and it mostly resembles the species from S. nigriverticella complex. For diagnostics of S. crassifoliae sp. nov. see figs 55, 56: from all other species of the complex, it is distinguishable by the large size of adults with wingspan 5.5 to 6.7 mm, dark hindwings (Fig. 56), and the abruptly widening leaf-mine (Fig. 4); the host-plants ( Quercus crassifollia and Q. crispipilis) also make this species distinctive.

Male (Fig. 7). Forewing length 2.4–3.1 mm; wingspan 5.5–6.7 mm. Head: palpi golden cream to greyish cream, sometimes with black scales distally; frontal tuft fuscous on vertex, pale beige-orange on frons (sometime these beige-orange piliform scales are less prominent or rubbed); scape and collar golden cream; antenna as long as half of forewing; flagellum with 27–28 segments, grey to fuscous on upper side, grey on underside. Thorax golden cream; tegula golden cream, with black darkenings anteriorly. Forewing golden cream, with distinctive black markings with purple or (and) blue iridescence: narrow basal fascia, median spot (Fig. 7), and broad subapical fascia; cilia grey, at forewing apex golden grey; underside of forewing brown-grey, with cream apical spot (Fig. 8) and with very weak (or without) purple iridescence. Hindwing and its cilia grey to dark grey, with no androconia or spots. Legs fuscous to dark grey on upper side, brownish cream to golden cream on underside. Abdomen dark grey to fuscous on upper side, golden cream on underside; anal tufts short, indistinct, grey cream; genital plates golden cream to brownish cream.

Female. Flagellum with 24–25 segments. Underside of forewing with more distinctive, ochre cream apical spot. Otherwise as male.

Male genitalia (Figs 10–17). Capsule slightly longer (255–270 µm) than wide (195–235 µm). Vinculum without lateral lobes, ventral plate short (30–40 µm). Uncus with two short, distally thickened lateral lobes (Figs 10, 13, 14, 16). Gnathos with two closely juxtaposed caudal processes (Figs 13, 14, 16). Valva (Figs 20, 21) 195– 205 µm long, with numerous long chaetae; apical process weakly individualized; transtilla with very short sublateral processes. Juxta X-shaped (Figs 12–14). Phallus (Figs 15, 17) 160–180 µm long, 50–80 µm broad; vesica without cornuti (Figs 15, 17).

Female genitalia (Figs 18–21, 55). Total length 1025–1055 µm. Apophyses anteriores (80–100 µm) much shorter than apophyses posteriores (120–180 µm) (Fig. 19). Vestibulum relatively narrow, without sclerites. Accessory sac very small. Corpus bursae oval to elongated, 295–330 µm broad, covered with numerous pectinations and with two connected, strongly thickened signa (Figs 20, 21); one signum is slightly longer than the other (Fig. 20).

Bionomics (Figs 1–6, 9). Mines in leaves (Figs 4–6). Host-plants: Quercus crassifolia Humb. & Bonpl (Fig. 2) and Q. crispipilis Trel. (Fig. 3), section Lobatae. Egg on upper side of the leaf. Larvae mine in January and February (in February most of leaf-mines are already empty). Very slender sinuous gallery filled with blackish frass abruptly widens (Figs 4–6). Larva pale green, with pale brown intestine (Fig. 6). Larval exit slit on upper side of the leaf. Cocoon (Fig. 9) beige cream; length 2.7–2.9 mm, maximal width 1.5 mm. Adults emerged in March.

Distribution. Known from Guatemala, occurring in montane mixed forests at elevation 1655–2500 m (Fig. 1).

Etymology. The new species is named after its host-plant Quercus crassifolia .

Remarks. Stigmella crassifoliae sp. nov. was previously identified and treated in Stonis et al. 2013b as S. nigriverticella (Chambers, 1875) because extremely close similarity of the male genitalia. However, an in-depth examination of the adults, leaf-mines and female genitalia of the series collected in Guatemala, as well as distributional and host-plant criteria, support S. crassifoliae as a separate species.