Generic features: Head smooth-scaled; Ocelli present; Antenna simple, scape without pecten; Labial palp S2 with ventral furrowed brush of scales, S3 smooth-scaled as long as S2; Forewing lanceolate, width 1/4 length; Hindwing subtrapezoidal, width 1/5 length, termen oblique, moderately excavated near apex, tornus rounded; V7&6 separate, V4 connate/slightly stalked with V3
Male genitalia: Valvae flat/tubular with bristles; sacculus present, not hooked; gnathos narrow at apex, hook-like
Male genitalia: Valvae flat/tubular with bristles; sacculus present, not hooked; gnathos narrow at apex, hook-like
Key to extant species of British Scrobipalpa
I have found this genus to be one of the most confusing of the British Lepidopteran fauna. Most are variable. S.costella is the only common species that can be readily and reliably identified without recourse to genital dissection (it has a large dark blotch on the costa of the forewing). S.murinella is the smallest of the genus and its size (ws9-10mm) hardly overlaps with any other. It is rare and has only been found on Rum, Coll and near Braemar. S.clintoni has only been found on the West coast of Scotland. This leaves 10 species for the lepidopterist in England to choose from.
Male genitalia - armature
Care should be taken to note the presence or absence of coremata (a paired bundle of long hair-like scales at the base of tergite 8) when dissecting out the genital capsule, as this feature is used at the first step in the key. Other key features are: shape of the posterior margin of the uncus (rounded or notched); relative extent of uncus and valvae; relative extent of saccus and pedunculus; relative length of sacculus and posterior process of vinculum; continuity or otherwise of posterior process of vinculum with median emargination; inclination of posterior processes of vinculum.
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Aedeagus
Features of the aedeagus are only referred to in one couplet of the key in MBGBI4.2. The following should be noted: shape of apical arc; shape of subapical arc; presence and shape of 2nd bar; connection of ventral bar or second bar to subapical arc; relative diameter of apical and basal portions.
MBGBI4.2 also uses degree of curvature of aedeagus but I have not found this a convincing distinction. 
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Key to Males
Coremata present
6 species
Posterior margin of uncus notched
Scrobipalpa suedella
Uncus not notched, usually rounded, in remaining 5 species Saccus distinctly exceeding pedunculus
Scrobipalpa costella
This species can usually be identified on external features. Of the remaining 4 species pedunculus may exceed the saccus in S.salinella and the saccus is on a level with or only slightly exceeds the pedunculus in S.samadensis/instabilella/artemisiella (The key in MBGBI4.2 also states that the uncus distinctly exceeds the valvae but this feature does not seem to be either true or to distinguish S.costella from these remaining 4 species - the uncus slightly exceeds the valvae in all 5). Apical arc of aedeagus broad and curved
Scrobipalpa instabilella
The aedeagus is also straighter and stouter, with less contrast between the apical half and the coecum, than in the remaining 3 species. The key in MBGBI4.2 distinguishes this species and S.salinella on the basis that the posterior process of the vinculum is distinctly shorter than the sacculus. Comparing the drawings in MBGBI4.2 does not lead me to think this a particularly clear distinction from the 2 species (S.samadensis/artemesiella) in which the posterior process is said to be 'hardly shorter than the sacculus'. In any event I am not convinced that the specimens I have identified as S.instabilella show a particularly short posterior process. The aedeagal features do however seem to be distinctive. Apical arc of aedeagus narrow with a long straight section
a) Posterior process of vinculum shorter and narrower than sacculus, only slightly curved away from midline.
Scrobipala salicorniae
b) Posterior process of vinculum similar size to sacculus, distinctly curved away from midline.
bi) Posterior process of vinculum squat
Scrobipalpa samadensis bii) Posterior process of vinculum slender
Scrobipalpa artemisiella
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Coremata absent
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Female Genitalia
Features to note in the female genitalia are:
Is the corpus bursae (CB) clearly defined? or is the transition from the ductus bursae (DB) gradual? Is the signum clearly in the CB or in the transition zone between DB and CB? Is the CB oval or spherical? Is the signum on the left or right? Presence and extent of any teeth on the concave surface of the signum. Is the DB straight or curved? |
Close-up of segment 8
The key in MBGBI4.2 uses features of the microscopic architecture of the ventral and ventrolateral zones of segment 8. This seems to require higher power microscopy than I have access to, and the distinctions made are not very clear.
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Key to females
Transition from DB to CB abrupt so that CB is clearly defined
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Transition from DB to CB gradual so that CB is not clearly defined
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Page published 30/09/11 | S.costella female image added, links added and an error corrected 07/11/2011 | amendments to aedagus structure image and text and to distinction between S.nitentella/obsoletella 11/10/2012 | S.salinella male added and key ammended 05/02/2012
