Stigmella tripartita Diskus & Stonis, sp. nov.
Creators: name: Stonis, Jonas R.
name: Diškus, Arūnas
name: Remeikis, Andrius
name: Davis, Donald R.
name: Solis, M. Alma
name: Torres, Nixon Cumbicus
Publisher: name: Zenodo
Year: 2016
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Lepidoptera
Nepticulidae
Stigmella
Stigmella tripartita

description: 3. Stigmella tripartita Diškus & Stonis, sp. nov.
(Figs. 3, 33–43)
Type material. Holotype: ♂ (see Remarks), ECUADOR: 15 km SW Cajabamba (Chimborazo Province), 1°45'41"S, 78°48'51"W, elevation 3870 m a.s.l., mining larvae on Baccharis buxifolia (Lam.) Pers. 19.ii.2007, field card no. 4874, leg. A. Diškus, J. R. Stonis, genitalia slide nos AD 622♂ (ZMUC). Paratype: ♂ (see Remarks), same label data as holotype, genitalia slide no. AD 624♂ (ZMUC).
Diagnosis. In the male genitalia, the set of three very large cornuti distinguishes S. tripartita sp. nov. from all other Stigmella species; the host-plant (Baccharis buxifolia) also makes this species distinctive.
Male (Fig. 38). Forewing length about 3.0 mm; wingspan about 6.5 mm (n=2). Head: palpi cream; frontal tuft brown to brown cream; scape cream to yellowish cream; antenna longer than half the length of forewing; flagellum with approx. 26 segments, grey.Thorax and tegula dark grey-brown to fuscous. Forewing dark brown-grey to fuscous, with slightly postmedian fascia; fascia broad to narrow, whitish grey or grey cream; terminal and tornal cilia pale grey-brown. Abdomen dark grey to fuscous (also see Remarks).
Female. Unknown.
Male genitalia (Figs 39–43). Capsule short (230–295 µm) but broad (235–240 µm). Vinculum with very small (25–30 µm), triangularly shaped lateral (anterior) lobes; ventral plate of vinculum short. Uncus 85–90 µm broad, with two small lobes, each bearing one (Fig. 41) or two papillae. Gnathos stout, with two caudal processes broadening basally (Fig. 41); central plate of gnathos large to very large, 85 µm broad, in the form of a trapezium (Fig. 41). Valva (Fig. 39) 180 µm long, 80–85 µm broad, with two apical processes (ventral process short and pointed); inner lobe almost straight or slightly bulged; transtilla with rounded sublateral processes or without processes, rounded at corners (Figs 41, 43). Juxta membranous, distinctly triangular, broadening caudally (Fig. 39). Phallus (Figs 40, 42, 43) very short (145–200 µm) but broad (120 µm); vesica with a set of three very large (up to 100 µm long) cornuti (Fig. 40); no small spinose cornuti developed.
Bionomics. Larvae mine in leaves. Host-plant: Baccharis buxifolia (Lam.) Pers. (Asteraceae) (Figs 34, 36). Larvae yellow to pale yellow, and mine in February. Contorted gallery of mine with central line of dark brown to black frass (approximately resembling the mines of the European S. myrtilella (Stt.)). Larval exit slit on upper side of the leaf. Cocoon grey-beige to grey-ochre; length 2.6–3.2 mm, maximal width 1.3–1.8 mm (Fig. 37). Adults emerged in March.
Distribution (Fig. 3). This species occurs high in the equatorial Andes (Ecuador) at altitudes between 3800– 3870 m (Fig. 33), mostly along roadsides (Fig. 35).
Etymology. The species name is derived from the Latin tripartitus (divided in three parts; triple) in reference to the unusual set of three very large cornuti of the male genitalia.
Remarks. This distinctive new species, associated with Baccharis buxifolia as a host-plant and possessing three large cornuti in the male genitalia, is described from the genitalia slides dissected from adults still enclosed within the pupa shell.
description: Published as part of Stonis, Jonas R., Diškus, Arūnas, Remeikis, Andrius, Davis, Donald R., Solis, M. Alma & Torres, Nixon Cumbicus, 2016, The first record of Baccharis L. (Asteraceae) as a host-plant genus for Nepticulidae (Lepidoptera), with description of new Stigmella species from South America, pp. 101-128 in Zootaxa 4136 (1) on page 110, DOI: 10.11646/zootaxa.4136.1.4, http://zenodo.org/record/261786