Stigmella mevia Remeikis & Stonis

Stonis, Jonas R. & Remeikis, Andrius, 2016, Southern Andean Stigmella sinuosa complex (Lepidoptera, Nepticulidae): unraveling problematic taxonomy with a pictorial key of adults?, Zootaxa 4136 (2), pp. 309-322 : 311-316

Stigmella mevia Remeikis & Stonis , sp. nov.

( Figs 7–12 , 23 )

Type material (23 Ƌ). Holotype Ƌ: ARGENTINA, Río Negro, S. C. de Bariloche, Colonia Suiza, elevation ca. 800 m, 9.xi.1981, Nielsen & Karsholt, genitalia slide no. RA525 ( ZMUC). Paratypes (22 Ƌ): 10 Ƌ, ARGENTINA, Neuquen, San Martin de los Andes, elevation ca. 640 m, 21.ix–31.x.1981, Nielsen & Karsholt, genitalia slide nos RA297, RA324, RA351, RA364, RA437, RA596, RA603, RA640, RA656, RA661 ( ZMUC); 1 Ƌ, Río Negro, S. C. de Bariloche, Colonia Suiza, elevation ca. 810 m, 5.xii.1978, Mision Cientifica Danesa, genitalia slide no. RA534 ( ZMUC);1 Ƌ, same locality, 9.i.1979, Mision Cientifica Danesa, genitalia slide no. RA295; 9 Ƌ, same locality, elevation ca. 800 m, 22.ix.–22.xi.1981, Nielsen & Karsholt, genitalia slide nos RA296, RA298, RA321, RA328, RA334, RA597, RA701, RA702, RA703; 1 Ƌ, CHILE, Malleco Provice, Nahuelbuta Natural Park (near Los Gringos Camp), elevation ca. 1300 m, 29.i–5.ii.1979, D. & M. Davis & B. Akerbergs, genitalia slide no. RA647 ( USNM).

Diagnosis. S. mevia belongs to S. salicis group (see Remarks under S. sinuosa sp. nov.). From the most similar S. sinuosa it differs in the strong golden gloss of the forewing, dark frontal tuft, darker antenna, longer apical processes of valva and uncus, and the specific set of cornuti with a large sickle-shaped cornutus.

Male ( Figs 7 , 11 ). Forewing length 3.1–3.3 mm; wingspan 6.7–7.2 mm. Head: palpi whitish cream; frontal tuft dark beige-brown to beige cream (occasionally); collar golden grey, occasionally with purple iridescence; scape white, occasionally grey-white with purple iridescence; antenna longer than half the length of forewing; flagellum with 37 segments, fuscous to dark grey (at certain angle brownish grey) on upper side, dark grey to grey on underside. Thorax and tegula golden grey to golden grey-brown, occasionally with strong purple iridescence. Forewing brown, at certain angle dark grey or slightly darker before fascia, but always with medium to strong golden gloss; fascia distinctly postmedian (subapical), silvery shiny, from distinctive and straight to ill-defined, strongly narrowed or fully interrupted in the middle; occasionally forewing with two large subapical spots instead fascia; additionally, some silvery shiny lamellar scales could occur just before fringe and form short, ill-defined apical (second) fascia; often area between fascia and fringe darker, with purple iridescence; fringe grey-brown, distally pale grey; underside of forewing grey-brown, without spots. Hindwing and its cilia brownish white on upper side and underside, at certain angle pale brown, occasionally brown; without androconia. Legs glossy grey, with some dark brown scales. Abdomen dark grey to fuscous on upper side and underside; anal tufts short, dark grey to greyish brown or pale brown; genital plates grey to dark grey.

Female. Unknown.

Male genitalia ( Figs 8–12 ). Capsule longer (320–325 mm) than wide (225–230 mm). Vinculum with long, occasionally slightly angular lateral lobes; ventral plate long. Uncus gradually narrowed caudally, with four small caudal lobes ( Figs 8 , 12 ). Gnathos with two very slender caudal processes ( Figs 8, 9 , 12 ). Valva ( Figs 9 , 12 ) 165– 170 mm long, with small to prominent inner lobe and two slender apical processes; transtilla with short transverse bar but without sublateral processes ( Figs 8 , 12 ). Juxta membranous, indistinct, triangularly shaped. Phallus ( Figs 10 , 11 ) 225–240 mm long, 105–110 mm wide; vesica with 6 to 10 (usually 8) various horn-like cornuti; one of the largest cornuti is distinctly curved, sickle-shaped ( Figs 10 , 11 ).

Bionomics. Host-plant: unknown. Adults fly in October–November, however some specimens were collected in late September, December, and early January (probably two different generations).

Distribution. Known mostly from the western (mountainous) Argentina, also central Chile, at elavations about 600–1300 m ( Fig. 23 ).

Etymology. The species name is derived from Latin mevia (a woman warrior) referring to the large curved (sickle-shaped) cornutus on the vesica.

Remarks. Among the specimens of the type-series, some color variation was observed (including the forewing’s purple iridescence which could be distinctive but sometimes is weaker or absent). It is rather unusual that the number of cornuti in the phallus varies, from 6 to 10.

Figures

FIGURE 11. Comparison of Stigmella sinuosa sp. nov. and S. mevia sp. nov.

FIGURE 12. Comparison of male genitalia of Stigmella sinuosa sp. nov. and S. mevia sp. nov.

FIGURE 23. Distribution of Stigmella sinuosa sp. nov. and S. mevia sp. nov.

FIGURES 7 – 10. Stigmella mevia sp. nov. 7, male adult, holotype; 8, male genitalia, holotype, genitalia slide no. RA 525; 9, valvae, gnathos and uncus, paratype, genitalia slide no. RA 534; 10, phallus, paratype, genitalia slide no. RA 295 (ZMUC).