Stigmella aromatica Diskus & Stonis 2021, sp. nov.

Stigmella aromatica Diškus & Stonis, sp. nov.

(Figs 9–11, 22–24, 28–30, 41–47, 65, 66, 68) lsid:zoobank.org:act: 42F003AD-AAE4-4A52-AD3B-E2DE745B8E19

Type material. Holotype: ♁, ECUADOR: SW of Quito, western slopes of the equatorial Andes, Via Aloag to Sto. Domingo, 0°26’46”S, 78°37’39”W, elevation ca. 3100 m, mining larva on Minthostachys mollis (Benth.) Griseb. (Lamiaceae), 24.ii.2000, ex pupa iii.2000, leg. R. Puplesis, genitalia slide no. AD1022 (USNM). Paratypes: 9 ♁, 6 ♀, same label data as holotype, genitalia slides nos AD815♁, AD819♁ (from adult in pupal skin, pinned adult unavailable), AD1021♁, AD1032♁, AD1027 ♀, AD1031 ♀ (USNM).

Diagnosis. The new species belongs to the Stigmella singularia species group, designated and characterized by Stonis et al. (2017a). Externally, males of S. aromatica sp. nov. differ from the most similar S. mentholica sp. nov. in the wide, median fascia of the forewing and distinctive apical fascia. In the male genitalia, S. aromatica differs from all other known Neotropical Stigmella, including species of the S. singularia group, by the combination of an uncus with two unique caudal lobes (Fig. 41), a large gnathos with two very close-set caudal processes (Fig. 43), a bifid juxta (Fig. 44), and a set of large, spine like cornuti (Figs 45–47). The host plant, Minthostachys mollis, also make this species distinctive among other Stigmella species, except for S. mentholica and S. odora sp. nov. However, S. aromatica differs from both species in the morphology of the leaf mine: the leaf mine of S. aromatica is a long, slender, sinuous gallery almost entirely filled with frass (Fig. 10), while the leaf mine of S. mentholica is a relatively short and wide gallery (Fig. 3), and the leaf mine of S. odora is combined of a very slender gallery and irregular blotch (Fig. 6).

Male (Figs 22–24, 30). Forewing length 2.0– 2.5 mm; wingspan 4.5–5.6 mm (n = 5). Head: palpi golden cream; frontal tuft large, dark orange; scape golden cream; collar golden cream but at certain angle may look metallic grey; antenna about 2/3 of the length of forewing; flagellum with 33–37 segments, brown-grey, golden glossy. Thorax and tegula concolorous with the forewing base. Forewing pale golden brown, strongly shining, with some purple iridescence along costa; postmedian fascia wide, comprised of silvery or golden shiny scales; apex of forewing brown with strong purple iridescence, and with a distinctive apical fascia of silvery or golden shiny scales (occasionally apical fascia is indistinctive, see Figs 28, 29); fringe grey, glossy, distally whitish; underside of forewing dark greybrown, without spots or androconia, except for a slender, scaleless spot at base. Hindwing grey to dark grey, without androconia; fringe grey. Legs glossy cream to grey; on upper side, covered with dark grey-brown scales. Abdomen blackish grey with purple iridescence on upper side, brown-grey on underside; genital segments pale brown; anal tufts short but distinctive, grey.

Female. Smaller than male; forewing length 2.1–2.3 mm; wingspan 4.7–5.2 mm (n = 5). Antenna shorter than in male, only slightly longer than half the length of forewing. Abdomen grey-brown on upper side and underside; genital segments pale brown; anal tufts short but distinctive, blackish grey to grey; ovipositor pointed. Otherwise as in male.

Male genitalia (Figs 41–47). Capsule longer (290–300 μm) than wide (175–210 μm). Vinculum with short, pointed lateral lobes. Uncus with unique caudal lobes (Fig. 41). Gnathos large, with two very close-set caudal processes (Fig. 43). Valva (Fig. 44) 200 μm long, with pointed, partially divided apical process (Fig. 44); transtilla without sublateral processes (Fig. 42). Juxta triangular, distally split (Fig. 44). Phallus (Figs 45–47) 210–330 μm long, 90–115 μm wide; vesica with about numerous large spine-like cornuti and a lateral set of small cornuti (Fig. 45).

Female genitalia (Figs 65, 66). Total length 995–1000 μm. Anterior apophyses gradually narrowing and bent distally; posterior apophyses slender, approximately as long as anterior ones (Fig. 66). Vestibulum without sclerites. Corpus bursae with a strongly folded distal part and round or oval-shaped basal part with many distinctive pectinations. Accessory sac small; ductus spermathecae without coils, but with a small, tube-like vesicle.

Bionomics (Figs 7–11). Host plant is Minthostachys mollis (Kunth) Griseb., Lamiaceae: Mentheae (Figs 7, 8). Larva yellow with indistinctive, yellowish brown intestine and pale brown head; feeds in February and probably in late January (note that in late February most of the leaf mines are already vacant). Prefer to occur in shady places. Leaf mine (Figs 9–11) is a long, slender, sinuous gallery almost entirely filled with black frass (Fig. 10); in old, vacant leaf mines, frass may turn brown or black (Fig. 9). Cocoon brown. Adults probably fly in March (indoors, emerged in March).

Distribution (Fig. 68). This species is known from a single locality in Ecuador, on the western slopes of the equatorial Andes, at elevation of ca. 3100 m, but the host plant has a much wider distribution in the northern and central Andes (see Discussion).

Etymology. The species name is derived from Latin aromaticus (aromatic), due to the minty aroma of essential oil of the host plant, Minthostachys mollis, and its leaf mines.