Stigmella incaica Diškus & Stonis, Diskus & Stonis, 2021

Stonis, Jonas R., Remeikis, Andrius, Diškus, Arūnas, Baryshnikova, Svetlana & Solis, M. Alma, 2021, What are the smallest moths (Lepidoptera) in the world?, Zootaxa 4942 (2), pp. 269-289: 276-280

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Stigmella incaica Diškus & Stonis

sp. nov.

Stigmella incaica Diškus & Stonis   , sp. nov.

Type material. Holotype ♂, PERU: Cusco Region, La Convención Province, Cerro Quintalpata , 13°0’22”S, 72°36’44”W, elevation 1270 m, mining larva, ex pupa vii.2018, leg. Arotaype-Puma, genitalia slide no. AD1030 ♂ ( ZIN) GoogleMaps   . Paratypes: 3 ♂, 6 ♀, same label data as holotype, genitalia slide nos AD1029 GoogleMaps   ♂ (from adult in pupal skin, no moths preserved), AD1028 ♀ ( ZIN)   .

Diagnosis. This species belongs to the Stigmella nivea   group (see Stonis et al. 2017a for group diagnosis). In the male genitalia, the combination of the gnathos with two well-separated caudal processes, the wide uncus with four distinctive caudal papillae, and a unique set of four clusters of sizewise different cornuti in the phallus easily distinguishes S. incaica   sp. nov. from all members of the S. nivea   group, including the most similar Ecuadorian S. apicibrunella Diškus & Stonis   , described and illustrated in Stonis et al. (2017c).

In the female genitalia, S. incaica   sp. nov. is very similar to S. apicibrunella   , but differs in the presence of only a few indistinctive spines in the ductus spermathecae that in S. apicibrunella   is heavily spined.

Externally, S. incaica   sp. nov. may be easily distinguished from all species of the S. nivea   group, except S. apicibrunella   , by the distinctly dark apex of the generally pale forewing (also see Remarks).

Male ( Fig. 10 View FIGURES 8–10 ). Forewing length 1.75–1.87 mm (n = 3, average mean = 1.83); wingspan 3.83–4.09 mm (n = 3, average mean = 4 mm). Head: palpi golden cream; frontal tuft orange-ochre; collar large, comprised of lamellar, golden cream to ochreous yellow scales; scape golden cream to ochreous yellow; antenna shorter than half the length of forewing; flagellum with about 22–23 segments, grey to dark grey, golden glossy, with some purple iridescence. Thorax and tegula smoothly scaled, golden cream with some blue and purple iridescence. Forewing golden cream to ochreous yellow, with some blue and purple iridescence, but apically and narrowly along costal margin brown-black with purple iridescence; fringe grey, golden glossy, with some purple or blue iridescence; underside of forewing dark grey to black-grey except a cream, small, elongated spot at base, without androconia. Hindwing and its fringe grey to blackish grey, without spots or androconia. Legs golden glossy, yellow cream, on upper side covered with blackish grey scales with purple iridescence. Abdomen dark metallic grey to black-grey on upper side and laterally, golden cream to almost grey on underside; genital plates golden cream; anal tufts absent (or indistinctive).

Female ( Figs 8, 9 View FIGURES 8–10 ). Forewing length 1.75–1.95 mm (n = 5, average mean = 1.87); wingspan 3.82–4.27 mm (n = 5, average mean = 4.09 mm). Similar to male. Antenna 1/3 length of forewing; flagellum with about 18 segments. The brown-black apex of the forewing with stronger purple iridescence than male.

Male genitalia ( Figs 11–18 View FIGURES 11–15 View FIGURES 16–21 ). Capsule longer (210–215 μm) than wide (140–155 μm). Uncus wide, with four distinctive papillae caudally ( Fig. 11 View FIGURES 11–15 ). Gnathos with two very slender and well separated caudal processes and angular central plate. Valva 130–135 μm long, with two slender and sharp apical processes; transtilla without sublateral processes, lobe-like laterally. Juxta membranous, indistinctive. Vinculum with small pointed lateral lobes, and medium short ventral plate. Phallus ( Figs 15–18 View FIGURES 11–15 View FIGURES 16–21 ) 220–260 μm long, 60–85 μm wide; vesica with a wide, distinctly interrupted band of cornuti comprised of four clusters: three clusters of large spine-like cornuti and one cluster of very large, horn-like cornuti.

Female genitalia ( Figs 19–21 View FIGURES 16–21 ). Total length about 950 μm. Anterior and posterior apophyses equal in length; anterior apophyses slender only distally, gradually widened proximally; posterior apophyses very slender all their length. Vestibulum narrow, without sclerites. Corpus bursae with a very large and wide, heavily folded part and a large, about 400 μm long, 280 μm wide basal body; pectinations distinctive, forming a band-like structure somehow resembling a weakly developed signum (see Fig. 20 View FIGURES 16–21 ). Accessory sac indistinctive, very small, folded; ductus spermathecae wide but with few indistinctive spines proximally, with a lobe-like vesicle, without coils. Abdominal apex tapered into relatively slender, but distally rounded ovipositor.

Bionomics ( Figs 22–26 View FIGURES 22–26 ). Host plant is unknown (unidentified, possibly Acalypha   sp., Euphorbiaceae   ) ( Fig. 22 View FIGURES 22–26 ). Larva pale greyish green with a dark green intestine and dark brown head; mines in leaves in June. Leaf mine ( Figs 23–26 View FIGURES 22–26 ) starts as a very slender sinuous or contorted gallery with a slender line of black, occasionally blackbrown frass; further on, the gallery gradually widens and frass is dispersed; at the final part of the gallery, the frass is collected in a slender, central line. Larval exit slit on upper side of the leaf. Adults fly in July.

DNA Barcode. One whole female specimen of the type series was COI barcoded, but not the holotype; sequences are available in GenBank under voucher/sample no. MW 438869 View Materials   .

Distribution. This species occurs on the eastern slopes of the Peruvian Andes ( Peru, Cusco Region) at altitudes about 1300 m.

Etymology. The species name is derived from the Spanish incaico or incásico (pertaining to the Incas; feminine) referring to the locality where the species was collected by our Quechua counterpart in the historical centre of the ancient Inca Empire in the Lucumayo river valley with close proximity to Machu Picchu.

Remarks. Note that S. apicibrunella   (see Stonis et al. 2017c) is larger than S. incaica   in all size parameters: the wingspan and male or female genitalia. Based on molecular data, the exact position of S. incaica   in the S. nivea   group will be discussed separately (Stonis et al. in prep.).


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