Stigmella acuta Diškus, Navickaitė & Remeikis, 2013

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 : 202-207

Stigmella acuta Diškus, Navickaitė & Remeikis , sp. nov.

( Figs 1–17 )

Type material. Holotype: ♂, Himalaya, India, Uttarakhand, Dehradun District (Mussoorie), 30°27'31''N, 78°01'46''E, elevation 1980 m, mining larva on Quercus acutissima , 15–18.viii.2010, ex pupa 02.ix.2010, genitalia slide no. AD480 (ZMUC). Paratypes: 1♂, the same label data, pupa, genitalia slide no. AD481; 1♀, Tehri Garhwal (Chamba), 30°20'39''N, 78°28'59''E, mining larva on Quercus acutissima , 24.viii.2010, ex pupa 06.ix.2010, genitalia slide no. RA265 (ZMUC).

Diagnosis. A distinctive, fuscous-winged species with a cream to pale orange fascia in the forewing; the pointed valva, M-shaped gnathos, uncus with four small caudal lobes, large acute cornuti, developed manica, androconial scales on male hindwing, and folded accessory sac in female genitalia indicate that it belongs to the Stigmella hemargyrella group. Externally, males of the new species can be easily distinguished from all other currently known S. hemargyrella group species, except the Fagus -feeding S. hemargyrella (Kollar) , by the basal patch of dark brown androconia in the hindwing. In male genitalia, S. acuta differs from all Stigmella species by the shape and number of the large and pointed cornuti in the aedeagus.

Male ( Fig. 8 ). Forewing length 2.3 mm; wingspan 5 mm. Head: palpi cream to orangish cream; frontal tuft orange to dark orange; collar and scape yellowish cream; antenna half length of forewing; flagellum with 27–28 segments, fuscous with purple iridescence. Thorax and tegulae fuscous with purple, blue and green iridescence. Forewings fuscous (slightly paler in basal third), with purple, blue and green iridescence and with yellowish, slightly shiny postmedian fascia; terminal cilia fuscous; tornal cilia dark grey; underside of forewing dark brown.

Hindwings grey, in basal third (except anal margins) densely covered with dark brown androconia with bluish and greenish iridescence; cilia grey; underside of hindwing grey, with no androconia. Legs fuscous on upper side, brownish cream to brown on underside. Abdomen dark grey-brown or fuscous with purple, green and golden iridescence on upper side, shiny, grey-cream (distally cream) with weak purple and green iridescence on underside; anal tufts brown-cream; plates cream.

Female ( Fig. 9 ). Antenna with 23–24 segments. Postmedian fascia of forewings pale orange. Hindwings and their cilia brown-grey, without androconial scales. Otherwise as male.

Male genitalia ( Figs 10–14 ). Capsule longer (335–345 Μm) than wide (210–215 Μm). Vinculum with two large lateral (anterior) lobes. Uncus with four small caudal lobes ( Figs 10, 11 , 14 ). Gnathos with two larger and pointed caudal processes ( Fig. 11 ). Valva ( Figs 10 , 13 ) 210–225 Μm long, basally broad, narrowed apically, with large chitinized and pointed apical process; inner lobe small and rounded; transtilla with long transverse bar and short, slender sublateral processes. Aedeagus ( Figs 10, 12 ) 265 Μm long, 95–125 Μm broad; vesica with basal band of large spine-like cornuti and a few separate (loose) very large spine-like cornuti; a few cornuti with rounded, plate-like extentions basally. Manica present, prominent (large) and spined.

Female genitalia ( Figs 15–17 ). Total length about 1000 Μm. Apophyses widely separated and equally long (about 160 Μm). Vestibulum broad, without sclerites. Corpus bursae oval, without signa, densely covered with long and prominent pectinations ( Fig. 17 ). Accessory sac 325 Μm long, heavily folded ( Fig. 16 ). Abdominal tip pointed.

Bionomics. Mines in leaves ( Figs 5–7 ). Host-plant: Quercus acutissima Carruth. (Fagaceae) ( Fig. 3 ). Egg on upper side of the leaf. Larvae mine in August. Contorted or sinuous gallery of mine filled with brown-black frass; the first half of the mine completely filled with frass; in the second half of the mine frass coiled, leaving clear margins ( Figs 6, 7 ). Larva pale green to yellowish, with red-brown intestine and dark brown head capsule. Larval exit slit on upper side of the leaf. Cocoon brown to ochre-brown; length 2.5 mm, maximal width 1.5 mm ( Fig. 4 ). Adults fly in September.

Distribution. It was found in mountainous broadleaf and mixed forests of the western Himalaya at altitude about 2 km ( Figs 1, 2 ); possibly common, as inferred from many empty leaf-mines that were observed in different localities.

Etymology. The species name is derived from the Latin acuta (sharp, pointed) in reference to the large, pointed cornuti in the male genitalia.

Stigmella cornuta Rocienė & Stonis , sp. nov. ( Figs 18–36 )

Type material. Holotype: ♂, China, Mutianyu, Huairou District, Beijing, 40°25'56''N, 116°33'20''E, elevation 390 m, mining larva on Quercus dentata , 7.viii.2013, ex pupa 18.ix.2013, leg. A. Rocienė, gen. slide no. AG 419 (ZIN).

Diagnosis. A fuscous-winged species without fascia in the forewing. Some male genital characters (the apically narrowed valva, interrupted transverse bar of transtilla, broad lobate vinculum, and the uncus with the weakly individualized lobes) slightly resemble features of the species of the S. betulicola group, including the Oriental S. xystodes (Meyrick) . However S. cornuta differs from all Stigmella species by the shape and number of the extremely large and pointed cornuti in the aedeagus and by the unusual shape of partially reduced caudal processes of gnathos. The combined leaf-mine (with a blotch-like second half) is also unique among Quercus - feeding Stigmella species.

Male ( Figs 25, 26 ). Forewing length 1.9 mm; wingspan 4.2 mm (n=1). Head: palpi cream; frontal tuft beigeorange; collar and scape cream; antenna with 23 segments, shorther then half of forewing length; flagellum fuscous brown on upper side and brownish cream on underside. Thorax: dorsum and tegulae concolorous with base of forewing. Forewing: mottled grey-brown, coarsely scaled (particularly in apical half), with weak greenish and purplish iridescence; fascia absent; cilia grey; underside of forewing uniformly fuscous brown. Hindwing and its cilia grey-brown, with no androconia. Legs brownish cream, with brown darkenings on foreleg upper side.

Female. Unknown.

Male genitalia ( Figs 27–36 ). Capsule longer (245 Μm) than wide (170 Μm). Vinculum with two short but broad lateral (anterior) lobes ( Figs 27–29 ). Uncus with large, weakly individualized anterior lobes ( Figs. 31, 32 ). Gnathos 85 Μm broad, with two anterior and two posterior (caudal) processes ( Fig. 33 ). Valva ( Figs 27, 30 ) 160 Μm long, basally broad, narrowed apically, with small chitinized apical papilla; inner lobe absent; transtilla with interrupted transverse bar ( Fig. 28 ), without sublateral processes. Aedeagus ( Figs 10, 12 ) 180 Μm long, 60–70 Μm broad ( Fig. 27 ); vesica with three extremely large pointed cornuti ( Figs. 34–36 ). Juxta membranous, narrowed medially ( Fig. 30 ). Manica absent.

Bionomics. Host-plant Quercus dentata Thunb. (Fagaceae) ( Fig. 20 ). Egg flat and oval, on upper side of the leaf. Larvae mine in August. The first half of the mine is a narrow contorted gallery completely filled with blackgreen frass ( Fig. 23 ) which turns brownish in old mines ( Fig. 24 ); in the second half of the mine gallery widens to an oval blotch with scattered black frass ( Figs 21, 22 ). Larval exit slit on upper side of the leaf. Cocoon brownish cream; length 1.8 mm, maximal width 1.3 mm ( Fig. 19 ). Adults fly in September.

Distribution. It was found in deciduous broad-leaved forests of NE China ( Fig. 18 ). Etymology. The species name is derived from Latin cornuta (horned) in reference to the extremely large cornuti of aedeagus.

Figures

FIGURES 1 – 7. Stigmella acuta Diškus, Navickaitė & Remeikis, sp. nov., bionomics. 1, 2, habitat, mountainous broadleaf and mixed forests of the western Himalaya, Mussoorie, 30 ° 27 ' 31 '' N, 78 ° 01 ' 46 '' E, elevation 1980 – 2000 m; 3, host-plant, Quercus acutissima Carruth., Fagaceae; 4, cocoon. Scale bar 1 mm; 5 – 7, leaf-mines with feeding larvae.

FIGURES 8 – 12. Stigmella acuta Diškus, Navickaitė & Remeikis, sp. nov., morphology. 8, male adult, holotype. Scale bar 1 mm; 9, female adult, paratype. Scale bar 1 mm; 10, male genitalia, paratype, gen. slide no. AD 481. Scale bar 100 m; 11, male genital capsule, holotype, gen. slide no. AD 480. Scale bar 100 µm; 12, aedeagus, holotype, gen. slide no. AD 480. Scale bar 100 µm.

FIGURES 13 – 17. Stigmella acuta Diškus, Navickaitė & Remeikis, sp. nov., genitalia. 13, male genital capsule, holotype, gen. slide no. AD 480. Scale bar 100 µm; 14, same, dorsal view. Scale bar 100 µm; 15, female genitalia, paratype, gen. slide no. RA 265. Scale bar 300 µm; 16, same, accessory sac. Scale bar 200 m; 17, same, pectinations of bursa copulatrix. Scale bar 100 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).

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.