Rhigognostis senilella

Rhigognostis senilella (Zetterstedt, 1839)

(Figs. 1–6)

Plutella senilella Zetterstedt, 1839: 1001. Type locality: Greenland. Holotype female in MZLU (not examined)

Material examined: 180 exx.

Greenland: 1 female, Kaysiarsuk, Igalikofjord [= Igaliko Fjord], 29.08. [18]89, Lundeck no 38 leg., Bang Hass coll., prep. gen. 481 G. Friese (det. Friese, 1962, Subeidophasia senilella Zett., = S. dalella Stt.), ZMHB; 12 females, 12 males, 3 specimens without abdomen, Missien P.E. Victor H. de Lesse, 1949, Groenland occ., 16.06.1949, MNHN; 1 female, W Grønland, Narssarssuaq, 31.08.1962, Niels L. Wolf leg., ZI; 146 exx. (females and males), from various locations and various colour forms, ZMUC.

Iceland: 1 female, 1 male, 24–26-VII- [1856], Staudinger coll., prep. gen. Friese no: 940, 941 (det. Friese, 1962, Subeidophasia senilella Zett., = S. dalella Stt.), ZMHB; 1 male, 5.08.1933, Reykjanes, Ísafj, S. Heding leg., prep. gen. N. L. Wolff no: 3705; 1 male, 24.07.[1939], ϸaralatursnes, B. Fristrup leg., 1 female, 4.08.1933, Ísafjörðdur, S. Heding leg., ZMUC.

Description. Forewing span 19–22 mm. Head coloured like wing background, covered with white and whitegrey erect scales, appressed only on frons. Antenna long, filamentous. Labial palp composed of 3 segments, central segment with erect scales. Maxillary palp reduced, hardly visible. Forewing elongate, with slightly pointed apex, varying in pattern, two colour forms can be distinguished, dominated by white or white-grey scales.

Light-coloured form. Scape and pedicel white-grey, flagellomeres similarly coloured, with narrow darker grey bands. Labial palp: first segment white-grey, second segment dominated by grey-brown scales, third segment white-grey. Forewing background white, with many scattered grey-brown scales; along costal margin, dark brown spots visible, two largest ones at about ½ and ¾ of wing length; dorsal margin white, with three conspicuous dark brown spots, two largest spots connected by oblique discontinuous bands with large spots near costal margin; basal area white, with scattered grey-brown scales; whitish area in apical part; small dark spots grouped along termen margin; cilia bicoloured, dark grey with a narrow dark brown band.

Dark-coloured form. Scape and pedicel grey, flagellomeres uniformly grey. Labial palp: first segment grey with a small proportion of white scales, second segment dark grey with characteristic erect white-grey scales, third segment uniformly white-grey. In forewing, subcostal vein (Sc) reaching costal margin beside 1/2 of wing length; radial veins free, R1–R4 reaching costal margin, R5 reaching termen margin near wing apex; medial and cubital veins free, M3 and Cu1 reaching termen margin close to one another; postcubital vein conspicuous only near dorsal margin, hardly visible in other part; anal veins A1–A2 free only near wing base, remaining parts fused, conspicuous; pterostigma conspicuous, no limited by veins Sc and R2. Forewing background light grey; small dark grey spots hardly visible along costal margin; two dark grey spots near dorsal margin; oblique bands poorly defined; small dark spots poorly visible near termen margin; cilia light grey.

Hindwing light grey, cilia long, coloured like wing background. Stalk of veins Sc+rR1 reaching costal margin at 4/5 of wing length; remaining radial veins R2–R5 fused, reaching costal margin near wing apex; medial veins M1–M3 and cubital veins Cu1–Cu2 free; postcubital vein CuP poorly visible only near wing base, remaining part conspicuous; anal veins A1–A2 free, conspicuous.

Abdomen cylindrical, coloured like wing background.

In male genitalia anal tube long, membranous. Uncus reduced. Tegumen poorly defined, usually its middle part very narrow. Socii wide, covered with hairs. Gnathos poorly visible, usually fused with socii. Saccus very long and narrow. Valva with a gently rounded apex, constricted at 2/3 of its length. Each valva near vinculum with apodeme, apodeme markedly narrowing in apical part, ending with small teeth. Aedeagus long and narrow, strongly sclerotized, in central part strongly convex; apex not widened but membranous with a single long, conspicuous, dentate, pointed spine, its two middle apical teeth clearly bifid; at 2/3 of spine length, numerous spinules visible on aedeagus wall; base of aedeagus much wider, ductus ejaculatorius large, membranous, sclerotized in middle part; aedeagus 1/3 longer than valva.

In female genitalia posterior and anterior apophyses long and thin; anterior apophyses hooked at apex. Ductus bursae sclerotized, markedly dilated near inception of corpus bursae, more sclerotized and twisted due to sclerotization in this part; only short section before inception of corpus bursae membranous, with a small membranous ductus bullae. Ductus bullae short, evenly thin, bulla seminalis large, membranous, ductus seminalis narrow, membranous. Corpus bursae oval, strongly sclerotized, signum absent.

Biology: Cardamine pratensis L. and Brassica sp. have been recorded as larval foodplants in Iceland. Adults visit flowers Saxifraga oppositifolia in the spring (Wolff 1971).

Distributional area: Greenland, Iceland (Fig. 13). It was also recorded from Alaska (Ferris et al. 2012), but the identity of these records should be verified.