Caryocolum amaurella Hering 1924

Caryocolum amaurella is a moth of the family Gelechiidae. It is found in Denmark, Fennoscandia, Germany, Austria, Switzerland, Italy, Estonia, Latvia, the Czech Republic, Slovakia, former Yugoslavia, Hungary, Greece, Ukraine and Russia. It is also present in Turkey. The species is restricted to warm and sunny habitats such as dry meadows and pastures from lowland localities to about 2,200 meters in the Alps.

The length of the forewings is 5–6 mm. The forewings are blackish, with scattered white and brown scales particularly along the dorsal margin and across the first quarter and middle. Adults have been recorded on wing from late June to late September.

The larvae feed on Lychnis viscaria. They initially feed between spun terminal shoots, but later feed within the stem. Larvae can be found in April and May.

Adult (Figs 4–5). Wingspan 10–14 mm. Segment 2 of labial palpus bone-white on inner and upper surface, blackish grey on outer and lower surface; segment 3 almost black with light tip. Antenna black, indistinctly lighter ringed. Head with light yellow frons and black neck; thorax and tegula black mottled with brown. Forewing blackish grey mottled with some light brown; base black; two indistinct black spots in fold; one oblique spot above it and one in cell; some white scales before and after these spots; costal and tornal spot small, white, rarely fused. Hindwing light grey. Variation. The colour of the forewings varies from greyish to blackish. Worn specimens look lighter than fresh ones. Sometimes there are no white scales in the middle of the wing. Male genitalia (Figs 8–9, 12–13). Uncus subovate; tegumen stout; transtilla membranous; valva short, moderately stout, apex rounded; sacculus short, with angular ventral and convex dorsal margin, apically pointed; posterior margin of vinculum with deep medial emargination and slight medial incision, two pairs of short processes developed; saccus long, comparatively broad at base, distal part gradually tapered; phallus long and slender, weakly curved, with some minute cornuti apically. Female genitalia (Figs 16–17). Segment VIII without processes, subgenital plate sub-triangular, with numerous narrow folds, separated from sclerotized lateral plates by membranous zone; apophysis anterior slightly longer than segment VIII; antrum moderately short, about one-third to one-quarter length of apophysis anterior, broadly funnel-shaped; posterior part of ductus bursae with pair of lateral sclerites, extending to anterior third of apophysis anterior, and with two tiny sclerites anteriorly; signum with crescent-shaped base, short and stout, strongly bent hook. Molecular data. The intraspecific divergence of the barcode region is high with mean intraspecific divergence of 3.01% and maximum intraspecific divergence of 4.62% (n=9). The distance to the nearest neighbour Caryocolum mucronatella is 5.21%, the divergence to the morphologically closest Caryocolum crypticum is 6.82%. The extraordinary high intraspecific divergence with 4 haplotypes is partially related to geographical pattern. However, we also found two haplotypes within one population in Finland and morphology does not support cryptic diversity.

With certainty known from scattered records from northern and Central Europe and Turkey. All the specimens from north of the Alps that we have been able to cross-check are correctly attributed to Caryocolum amaurella. However, recent records from Ukraine (Bidzilya and Budashkin 2009) and Russia (southern Ural Mountains) (Junnilainen et al. 2010) have to be re-examined due to a possible mix-up with Caryocolum crypticum. Records from Switzerland are dubious, and at least in one instance refer to the new species, whereas those from France (Nel 2003) are confirmed (see Huemer and Karsholt 2010, Fig. 154c). Bionomics. The larva has been recorded feeding on Silene viscaria (L.) Jess (= Lychnis viscaria L. (Caryophyllaceae) (Huemer and Karsholt 2010), while the other stated host-plants, namely Silene otites (L.) Wibel (Burmann 1990) and Silene nutans L. (Huemer 1989a), refer to Caryocolum crypticum. Schütze (1926, 1931) gives a detailed account of the life-history. The larva feeds in April and May in the young terminal leaves which are – without spinning – attached to a tube where the larva is hidden. Dark frass is frequently extruded at the tip of the larval dwelling. Later it bores into the stem and the shoots often become swollen and stunted. Pupation takes place on the ground in a cocoon among debris. The adult occurs from late June to early September and it is attracted to light. Caryocolum amaurella is restricted to warm and sunny habitats such as dry meadows and pastures. Vertical distribution: from lowland localities to about 2200 m in the Alps.