Micrurapteryx gradatella ( Herrich-Schaeffer , 1855)

Kirichenko, Natalia, Triberti, Paolo, Mutanen, Marko, Magnoux, Emmanuelle, Landry, Jean-Francois & Lopez-Vaamonde, Carlos, 2016, Systematics and biology of some species of Micrurapteryx Spuler (Lepidoptera, Gracillariidae) from the Holarctic Region, with re-description of M. caraganella (Hering) from Siberia, ZooKeys 579, pp. 99-156 : 105-108

Taxon classification Animalia Lepidoptera Gracillariidae

Micrurapteryx gradatella ( Herrich-Schaeffer, 1855) Figs 3, 13, 18, 24, 25, 40, 41, 59-64

Citations.

[No genus Gradatella Herrich-Schäffer, [1854]: plate 21: fig. 992 [unavailable]]

[ Euspilapteryx Gradatella Herrich-Schäffer, [1855]: 293. Type locality: near Regensburg, Germany]

[ Gracilaria gradatella ; Staudinger and Rebel 1901: 208]

[ Parectopa gradatella ; Meyrick 1912: 21; Benander 1944: 122; Hering 1957: 600, 1110]

[ Micrurapteryx gradatella ; Spuler 1910: 409; Bengtsson and Johansson 2011: 103]

Original description.

Alis anter. Margine interiore albo, triinciso. Etwas kleiner als vorige [ kollariella ], mit schmaleren Vorderflügeln, deren Vorderrandsstriche desshalb schräger stehen, aber feiner und länger sind, der erste geschlängelt, dem zweiten genähert, deren weisser Innenrund einwärts drei Zachen bildet, zwischen welchen die weisse Farbe tief schwarz ausgefüllt ist. Ich fand 3 Exemplare an verschiedenen Stellen bei Regensburg, im Mai.

[English translation] "Somewhat smaller than previous, with narrower forewings, and front-marginal-dashes therefore more angled but finer and longer, the first sinuate [translates as ‘tortuous’], adjacent to the second, in which three inward teeth are formed by the white inner border, with deep black filling between the white colouration. I found 3 specimens in various places near Regensburg in May."

Material examined.

Adult (9): 1♀, Norway, HEs, Elverum, Hernes, 1a, 28.VI.1981, Lathyrus montanus , O. Karsholt, slide TRB4060; 2♀, Norway, HEs, 20.VI.1961, Norway, Lathyrus montanus , K. Larsen, slide MIC6942; 1♂, Predota, Mezösig [ Mezöseg, Cluj County, Romania], 24.6, slide TRB755; 2♂, FIN V [Finland], Turku, 670:23, e.l. 6.2000, T. Mutanen leg., Lathyrus linifolius , slide TRB4091, TRB4095; 1♂, FIN V [Finland], Turku, 670:23, e.l. 6.1998, Lathyrus linifolius , slide TRB4081; 2 ♂, Russia, Siberia, Krasnoyarsk (Yenisei river bank, near), Vicia amoena , 3.VII.2015, reared from mines, N. Kirichenko, slides NK-82-15-1, NK-82-15-2.

Pupa (7): Finland V: Turku, 6611:3230 mine, 12.6.2008 on Lathyrus linifolius , J. Itämies leg.; Finland V: Turku, 6714:234 mine, 19.06.2000 on Lathyrus linifolius , J. Itämies leg.; Finland, Ab Turku, collected June 2005 on Lathyrus linifolius , Markus J. Rantala leg. Larva (1): Finland, Ab Turku, collected June 2005 on Lathyrus linifolius , Markus J. Rantala leg.

Diagnosis.

Superficially, this species can be confused with Micrurapteryx kollariella (Figs 17, 20, 30-31, 47), widespread in Europe east to Kazakhstan. However, the latter can be distinguished by its forewing pattern with wider costal strigulae and white dorsal margin not denticulate. In male Micrurapteryx kollariella , the coremata are very long; the valvar apex is more protruded than in Micrurapteryx gradatella ; the saccular apex has a strong, incurved bifurcate tooth; and the phallus is anteriorly widened and deeply invaginated and with fine lateral serrations (Figs 30, 31); in female Micrurapteryx kollariella , S6 is weakly sclerotized and less developed, the antrum is widest near the ostium, and the signa are a pair of finely denticulate plates (Fig. 47); in Micrurapteryx gradatella the antrum is elongate, cylindrical and widest more anteriorly. For differences with Micrurapteryx caraganella , see under that species.

Description of adult

(Fig. 3). Wingspan 9.5-11.5 mm.

Head. Frons and vertex white, sometimes with intermixture of brown scales on vertex, around eyes and at base of antenna. Labial palpus white, rather long and slender, upturned, spotted with dark brown in medial and apical segment; maxillary palpus about half of apical segment of labial palpus, outer side fuscous. Antenna fuscous, scape and pedicel white ventrally, remaining articles ringed with paler colour; pecten absent.

Thorax. Dorsum and venter white, tegulae dark brown. Legs white, tibiae and tarsi annulated with dark brown; fore coxa and femur grey outwardly. Forewing dark brown in ground colour with white markings; costal margin with 5 white strigulae; first three almost parallel, oblique and bent outwards; first costal strigula with basal half parallel to costa, then oblique and fragmented; second often obsolescent; fourth and fifth semicircular, often both touching opposite margin; dorsal margin white in basal two-thirds, with two or three white projections, the more distal one almost touching the first costal strigula; apical spot black, not quite touching 5th strigula; cilia white around apex to tornus, with dark brown tips forming a line which projects a little at apex; hindwing grey ochreous, cilia pale grey.

Abdomen. Brown dorsally and white latero-ventrally. Segment 7 in the male with pair of coremata of thin scales about half width of sternum (Fig. 13). In the female sternum 6 more strongly sclerotized with a slight convexity on the proximal margin (Fig. 18).

Male genitalia (Figs 24, 25). Tegumen short, subtriangular, with no setae; tuba analis membraneous, braced by pair of sclerotized lateral bars, produced beyond tegu men, a small microspinose area ventroapically. Valva longitudinally cleft, costal margin slightly concave, cucullus lobe rounded; sacculus markedly developed, rectangular, lower margin with large, sharp, downward-oriented tooth, distal half lined with row of denticles. Phallus tubular, nearly as long as valva, straight, base bifurcate, dorso-medially with small spine, median ridge more or less serrated; vesica with two cornuti, first elongate, spear-like, one-third length of phallus, and second smaller, spiniform.

Female genitalia (Figs 40, 41). Anal papillae rather short, posterior apophyses shorter than anterior ones. Segment 8 short, about same length as anal papillae, weakly sclerotized. Sternum 7 markedly sclerotized, elongate-subtriangular. Ostium bursae rather narrow, rounded, at apex of S7. Antrum sclerotized, subcylindrical with anterior portion swollen; distal two-thirds of ductus bursae irregularly sclerotized with dense papillate microsculpture and one half-twist, proximal third membranous, inception of ductus seminalis ventrally on twisted portion. Bursa copulatrix slender, with pair of opposite signa each as cluster of 2-3 spines. Ductus spermathecae with efferent canal forming 3 or 4 coils before vesicle (not shown). Segment 6 shorter than or equal to preceding ones, sternum strongly sclerotized, transversely trapezoid, anterior margin with slight medial convexity.

Pupa.

Maximum length 5.5 mm; width 1.3 mm; vertex just shorter than frons. Frontal process (cocoon cutter) a transverse ridge strongly and irregularly dentate; frontal setae not visible, clypeal setae paired, very reduced and nearly contiguous. Antenna extended to abdominal segments A9; forewing to A5 or A6; hind leg to A10 or slightly longer than abdomen. Setae D1, L1 and SD1 present on abdominal segment A1-A7. Patočka and Turčáni (2005) report seta D1 on segment 7 but this was not found in the specimens examined. Cremaster consisting of a ring of five pairs of small spines, dorsal pair slightly enlarged and more closely set, two ventral pairs very small.

Larva.

Very similar to Micrurapteryx kollariella and Micrurapteryx caraganella . Last larval instars of this species were studied in detail by Grandi (1933) and no structural differences were discovered. For description, see Micrurapteryx caraganella below.

Biology.

Lathyrus linifolius (Reichard) Bässler [Syn. Lathyrus montanus Bernh., Lathyrus linifolius subsp. montanus (Bernhardi) Bässler, Orobus tuberosus L.], Lathyrus tuberosus L. and Vicia sepium L. ( Hering 1957, Noreika 1997, De Prins and De Prins 2015, Bengtsson and Johansson 2011, Ellis 2015), Lathyrus linifolius in Finland (present study), Vicia amoena in Siberia (Figs 1, 59-61). Found in meadows and along forest edges. Flight period from mid-June to mid-July ( Bengtsson and Johansson 2011). Larvae mine on the upper leaf surface, forming a blotch, initially whitish green then turning brown (Figs 59-62). Most frass is ejected from the mine ( Hering 1957). Pupation takes place outside the mine (Figs 63-64).

Distribution.

Micrurapteryx gradatella is known from Finland, Norway, Sweden, Germany, Poland, Romania, Spain ( Karsholt and Nieukerken 2015), Ukraine ( Noreika 1997), Tajikistan ( Puplesis et al. 1996), the central part of European Russia, the Urals, Siberia, and the Russian Far East (Amur oblast exclusively) ( Sinev 2008). Reports from Tajikistan and the Urals need to be verified and, probably, those of the Russian Far East refer to Micrurapteryx caraganella .