Kessleria cottiensis , Huemer, Peter & Mutanen, Marko, 2015

Huemer, Peter & Mutanen, Marko, 2015, Alpha taxonomy of the genus Kessleria Nowicki, 1864, revisited in light of DNA-barcoding (Lepidoptera, Yponomeutidae), ZooKeys 503, pp. 89-133: 89

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scientific name

Kessleria cottiensis

sp. n.

Taxon classification Animalia Lepidoptera Yponomeutidae

Kessleria cottiensis  sp. n.

Type material.

Holotype. ♂, "ITALIA, Prov. Torino Alpi Cozie, 2150 m Colle delle Finestre 27.7.1990 leg. Huemer & Tarmann" "YPO 58 ♂ P. Huemer" (TLMF).

Paratypes. Italy: 13 ♂, 7 ♀, same data, genitalia slides YPO 59 ♂ P. Huemer, YPO 77 ♂ P. Huemer, DNA barcode IDs TLMF Lep 03106, TLMF Lep 03107, TLMF Lep 03108 (TLMF); 3 ♂, 6 ♀, same data, but V. delle Finestre, 1700 m, genitalia slides YPO 66 ♂ P. Huemer, YPO 67 ♀ P. Huemer (TLMF). France: 1 ♂, Dep. Hautes-Alpes, Nevache, 1950m, 31.7.2001, leg. Nel, genitalia slide 12937 J. Nel, DNA barcode ID TLMF Lep 03144 (TLMF); 1 ♂, Dep. Hautes-Alpes, Vallee de la Claree, 2000 m, 3.7.2002, leg. Nel, genitalia slide 14644 J. Nel, DNA barcode ID TLMF Lep 03142 (TLMF).


Kessleria cottiensis  resembles other taxa of the Kessleria alternans  -group in wing markings and colour (Figs 2-11), but the male differs in the on average smallest forewing length of 7.59 mm (n=14) vs. 8.75 mm (n=13) in Kessleria wehrlii  , 8.55 mm (n=26) in Kessleria alternans  , 8.05 mm (n=6) in Kessleria alpmaritimae  and 8.25 mm (n=6) in Kessleria dimorpha  . Compared to Kessleria wehrlii  and Kessleria alpmaritimae  , the whitish suffusion of the forewing is largely reduced. The ochre-brown markings, which are well present in Kessleria alternans  , are almost completely absent. The female of Kessleria cottiensis  is also distinctly smaller than Kessleria alternans  , with a forewing length of 6.13 mm (n=8) on average vs. 7.58 mm (n=11), whereas females of Kessleria cottiensis  and Kessleria alpmaritimae  are indistinguishable. Kessleria wehrlii  is insufficiently known from only a single worn female specimen. Compared to the genetically nearest neighbour Kessleria dimorpha  , which is similar in forewing length (6.0 mm, n=4), the hindwings are slightly less reduced and the ground colour of the forewing is much lighter. Diagnostic characters in genitalia are generally weak. The male genitalia differ from Kessleria alpmaritimae  by the medially strongly widened valva, from Kessleria alternans  by the more slender cornuti, from Kessleria wehrlii  by three instead of four cornuti, and from the nearest neighbour Kessleria dimorpha  by the distinctly longer phallus (1.65-1.70 mm vs. 1.32-1.36 mm) (Figs 12-21). The female genitalia show no diagnostic characters to related species of the Kessleria alternans  -group (Figs 22-31).


Male (Fig. 4). Head covered with erected whitish hair-like scales; antennae dark grey-brown, indistinctly lighter ringed; thorax and tegulae dark grey-brown. Forewing length 7.0-8.8 mm ( Ø 7.59 mm; n=14); ground colour dark grey-brown, mottled with whitish scales, particularly in distal half, forming indistinct patches in fold and on costa at about 4/5; irregular black dots on veins and few brown scales in medial part of wing; oblique blackish fascia at about 1/3 to 1/2 indistinct; termen mixed whitish-grey, dark grey-brown in apical part; fringes light grey, darker in apical area. Hindwing dark grey, fringes with dark grey base, distal part light grey.

Female (Fig. 5). Head covered with erected whitish hair-like scales; antennae grey-brown, distinctly ringed whitish; thorax and tegulae whitish. Forewing length 5.8-6.3 mm ( Ø 6.13 mm; n=8); ground colour whitish, mottled with black scales, particularly along veins and in tornal part, patches of brown scales in medial part of wing from base to end of cell; oblique blackish fascia at about 1/3 to 1/2 indistinct, separated into larger dash-like patch and reduced dot; termen whitish with some dark grey-brown mottling in apical part; fringes greyish-white, darker in apical area.

Male genitalia (Figs 14-15). Socii long and slender, with apical spine; anterior margin of tegumen with medial process; gnathos broadly tongue-shaped, smooth; valva moderately slender, length 0.66-0.70 mm, medially distinctly widened, maximum width of about 0.24-0.26 mm, densely covered with long hairs in medial part and short setae on ventromedial margin, ventromedial part weakly convex, distal part slender with ventrally convex and dorsally projected apex, costa strongly sclerotized with some distal dentation; sacculus oval, weakly confined, densely covered with strong setae; saccus sizeable in length, about 0.38-0.42 mm, stout, about same width throughout, apex rounded; phallus ca. 1.65-1.70 mm long and slender, straight, apically with distinct reticulate sculpture, uneverted vesica with ca. 0.76-0.80 mm long sclerotized part, three prominent needle-shaped, one single, the other basally connected, cornuti of about 0.46-0.51 mm in length.

Female genitalia (Figs 23, 28). Genitalia ca. 4.9 mm in length; papilla analis large, densely covered with long setae; apophysis posterior rod like, ca. 0.70 mm, about length of apophysis anterior; apophysis anterior rod like; posterior part bifurcated with straight dorsal and inwardly curved ventral branch; lamella postvaginalis with large sclerotized mediolateral patches, covered with microtrichia, medial area less sclerotized, posteriolateral part with hump, covered with some long setae; ostium bursae membranous; antrum weakly sclerotized, funnel-shaped; ductus bursae very long, about 2.8 mm, from entrance of ductus seminalis to transition into corpus bursae covered with finely granulous sculpture, particularly in posterior and anterior part, ductus bursae extended into posterior part of corpus bursae, entrance to corpus bursae weakly widened; corpus bursae well delimited, about 1.2 mm in length, ovoid, with small plate-like signum.

Molecular data.

The average intraspecific divergence of the barcode region is 0.0% (n=5). The minimum distance to the nearest neighbour Kessleria dimorpha  is 1.86%, whereas the minimum divergence to Kessleria alternans  , Kessleria alpmaritimae  and Kessleria wehrlii  ranges from 2.65% and 2.98% to 3.63%, respectively.


The species name refers to the type locality in the Cottian Alps (Alpi Cozie, Alpes cottiennes).


(Fig. 32). Only known from a small area in the southwestern Alps (Cottian Alps) of Italy and France. An alleged Kessleria alternans  from the Graian Alps ( Huemer and Tarmann 1992) likely refers to Kessleria cottiensis  , but the specimen in question could not be re-examined.


Host-plant and early stages unknown. The adults were collected in late July. The flight period can most likely be further prolonged, depending on snow coverage and elevation. A specimen collected earlier during the summer, on June 9th, by Jäckh in Valle delle Finestre ( Huemer and Tarmann 1992) probably belongs to Kessleria cottiensis  . The adults were collected during the day, flying freely in the morning hours and flushed out from their resting places with a bee-smoker. The species occurs in alpine grassland interspersed with calcareous rocks. Vertical distribution: from about 1700 m to 2150 m.


Kessleria cottiensis  described here was already suspected to be distinctive from Kessleria alternans  by Huemer and Tarmann (1992), who illustrated adults (Figs 6-7) and cornuti of male genitalia (Fig. 105).