Group B: Forewing white with scattered fuscous scales
6 Species
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1. Forewing with a diffuse fuscous discal stigma in apical half; scape (with projecting scales but) not distinctly tufted > 37.039 Coleophora hemerobiella
The stigma may be sufficiently diffuse as to be uncertain, in which case the fairly even distribution of fuscous scales and the absence of a distinct tuft on the antennal scape should exclude the other species in Group B, provided that the specimen is reasonably fresh.
The remaining 5 species are sufficiently similar in both external and genital appearance that they will usually require a combination of features for confident identification. In general, the key to the external features given here should be used to provide an indication as to which is the most likely species, but this should be confirmed by examination of the genitalia.
Sizes overlap but C.ibipennella and C.betulella average smaller than C.anatipennella, C.albidella and C.kuehnella such that at forewing length <6.5mm the former two species are more likely and at forewing length >6.5mm the latter three species are more likely. |
The remaining 5 species all have a distinctly tufted antennal scape (see images below).
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2. Fuscous scales randomly scattered > 2 species
2a Fuscous scales dark > 37.049 Coleophora anatipennella
2b Fuscous scales pale > 37.050 Coleophora albidella
In my experience the forewing of C.albidella can appear almost entirely white
2b Fuscous scales pale > 37.050 Coleophora albidella
In my experience the forewing of C.albidella can appear almost entirely white
3. Fuscous scales predominantly distributed along the veins > 3 species
MBGBI3 also distinguishes these species on the basis that the costal cilia are white-tipped in C.keuhnella and C.ibipennella, but not in C.betulella. I have not been convinced that the costal cilia of C.betulella are any less white-tipped than those of the other two species, either from observations of my own material or from web images labelled as C.betulella.
White-tipped costal cilia should be looked for towards the apex. It is usually a narrow whitish margin to the line of fuscous cilia. It may be easier to see in the live moth at rest and is likely to disappear, or at least become uncertain, with any degree of wear. All 5 of the "difficult" species have a line of black scales extending along the costa from the forewing base. According to MBGBI3, in C.ibipennella this line is confined to the base of the costa; in C.kuenella it extends to ~⅔; in C.betulella it is variable and may extend to anything from ⅖ to the full length of the costa. I have not found any convincing association between the extent of black along the costa and identifications confirmed by genital dissection. Note that abrasion and wear can also make the costa appear dark. |
C.betulella is very variable and may have the veins sufficiently well-marked that it is looked for in Group E or H, but differs from species in those groups in having a white ground colour.
All 5 of the "difficult" species have the antenna white, ringed ochreous-fuscous. In C.betulella and C.albidella the rings may be inconspicuous, so that the antenna appears more-or-less all white. A specimen with a white forewing with veins lined by fuscous scales with forewing length < 6.5mm and an almost unmarked antenna should be C.betulella. A specimen with a white forewing with randomly scattered fuscous scales with forewing length >6.5mm and an almost unmarked antenna should be C.albidella
Male genitalia
1. With the genitalia laid flat the anterolateral margin of the sacculus is distinctly angular in C.anatipennella, smoothly curved in C.albidella.
2. The valvula of C.albidella is relatively longer and narrower. An attempt to express this in more absolute terms is demonstrated in the images below.
Taking the breadth of the valvula at its base (a) and the length of the valvula (b): b/a = 2-3 for C.anatipennella and ~5 for C.albidella.
3. The apex of the sacculus (c) reaches past the anterior margin of the valvula in C.anatipennella but does not reach the valvula in C.albidella
4. The sacculus of C.albidella has a fairly large somewhat triangular flap (d) extending from ~midway along its anterolateral margin; this flap is minimal or absent in C.anatipennella. (As this flap projects at ~90° to the plane of the sacculus, this feature is easier to see before the preparation is laid flat).
2. The valvula of C.albidella is relatively longer and narrower. An attempt to express this in more absolute terms is demonstrated in the images below.
Taking the breadth of the valvula at its base (a) and the length of the valvula (b): b/a = 2-3 for C.anatipennella and ~5 for C.albidella.
3. The apex of the sacculus (c) reaches past the anterior margin of the valvula in C.anatipennella but does not reach the valvula in C.albidella
4. The sacculus of C.albidella has a fairly large somewhat triangular flap (d) extending from ~midway along its anterolateral margin; this flap is minimal or absent in C.anatipennella. (As this flap projects at ~90° to the plane of the sacculus, this feature is easier to see before the preparation is laid flat).
Coleophora kuehnella vs Coleophora ibipennella vs Coleophora betulella
These three are separable on features of the gnathos, tegumen and position of the apex of sacculus relative to the anterior margin of the valvula:
Coleophora kuehnella: tegumen broad; apex of sacculus well short of valva; median lobe of the gnathos triangular
Coleophora ibipennella: tegumen narrowed in middle (figure-of-eight); sacculus reaches past anterior margin of valvula; median lobe of gnathos ovoid
Coleophora betulella: tegumen straight, narrow; apex of sacculus just reaches anterior margin of valvula; median lobe of gnathos ovoid with dark margins
Coleophora kuehnella: tegumen broad; apex of sacculus well short of valva; median lobe of the gnathos triangular
Coleophora ibipennella: tegumen narrowed in middle (figure-of-eight); sacculus reaches past anterior margin of valvula; median lobe of gnathos ovoid
Coleophora betulella: tegumen straight, narrow; apex of sacculus just reaches anterior margin of valvula; median lobe of gnathos ovoid with dark margins
Female genitalia
Coleophora anatipennella vs Coleophora albidella
These two are very similar. According to MBGBI3 the key difference is in the posterolateral margin of the ostial plate - this is obtusely angular in C.anatipennella and fairly smoothly rounded in C.albidella.
These two are very similar. According to MBGBI3 the key difference is in the posterolateral margin of the ostial plate - this is obtusely angular in C.anatipennella and fairly smoothly rounded in C.albidella.
Coleophora kuehnella vs Coleophora ibipennella vs Coleophora betulella
C.ibipennella and C.betulella are very similar. The only consistent differences I can suggest are that in C.ibipennella the ostial plate is less transverse with the anterior apophyses about as long as the ostial plate; while in C.betulella the ostial plate is more transverse with the anterior apophyses about a little longer than the ostial plate. Possibly the signum of C.ibipennella curves abruptly near the apex of the spike; while that of C.betulella curves more evenly from the base of the spike. MBGBI3 illustrates coarser spiculation of the ductus bursae in C.betulella - but I have been unable to confirm this feature.
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