Stigmella tripartita Diškus & Stonis,

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, Zootaxa 4136 (1), pp. 101-128: 110

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Stigmella tripartita Diškus & Stonis

sp. nov.

3. Stigmella tripartita Diškus & Stonis  , sp. nov.

( Figs. 3View FIGURE 3, 33–43View FIGURES 33 – 38View FIGURES 39 – 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. 38View FIGURES 33 – 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 39–43View FIGURES 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. 41View FIGURES 39 – 43) or two papillae. Gnathos stout, with two caudal processes broadening basally ( Fig. 41View FIGURES 39 – 43); central plate of gnathos large to very large, 85 µm broad, in the form of a trapezium ( Fig. 41View FIGURES 39 – 43). Valva ( Fig. 39View FIGURES 39 – 43) 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, 43View FIGURES 39 – 43). Juxta membranous, distinctly triangular, broadening caudally ( Fig. 39View FIGURES 39 – 43). Phallus ( Figs 40, 42, 43View FIGURES 39 – 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. 40View FIGURES 39 – 43); no small spinose cornuti developed.

Bionomics. Larvae mine in leaves. Host-plant: Baccharis buxifolia (Lam.) Pers.  ( Asteraceae  ) ( Figs 34, 36View FIGURES 33 – 38). 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. 37View FIGURES 33 – 38). Adults emerged in March.

Distribution ( Fig. 3View FIGURE 3). This species occurs high in the equatorial Andes ( Ecuador) at altitudes between 3800– 3870 m ( Fig. 33View FIGURES 33 – 38), mostly along roadsides ( Fig. 35View FIGURES 33 – 38).

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.


Zoological Museum, University of Copenhagen