Scrobipalpa
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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 ¼ length; Hindwing subtrapezoidal, width ⅕ 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
S.costella is the only common species that can be readily and reliably identified without 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 (ws: 9-10mm) 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 distinguish.
Male genitalia
The 5 images here show the male genitalia of S.obsoletella. Left to right, top to bottom: 1) genital capsule, natural position, ventral view; 2) genitalia, aedeagus removed, slide prep; 3) valvae and vinculum, labelled; 4) tegumen, labelled; 5) aedeagus, lateral view, labelled.
Note that the labels used here differ from those applied in MBGBI. An explanation is given below. Features used in distinguishing the species are: relative extent of costae and uncus; relative extent of saccus and pedunculus; shape of the posterior margin of the uncus; details of the shape of the saccular processes and median emargination; shape of the apical arm of the aedeagus. |
Coremata The image left shows the dorsal and ventral plates of A8 of S.suaedella. When dissecting out the genital capsule, care should be taken to note the presence or absence of coremata - a paired bundle of long hair-like scales at the base of the dorsal plate of A8 close to the junction of the two plates. They are easily overlooked if you are not aware of this first step in the key. |
Labelling of parts of the male genitalia.
The main differences between my interpretation of the genitalia and that illustrated in MBGBI is in the junction between valvae and vinculum and in the consequent labelling of the parts of the valvae.
I have taken the view that the saccus is the median component of the vinculum, that the valvae are composed of the fused costa + sacculus, and that the two sacculi are partially fused in the midline at the median emargination. The labelled image of the valvae and vinculum shows a dashed line at the clear junction between valvae and vinculum that results from this interpretation - and this interpretation can be applied to all Lepidopteran families.
MBGBI appears to have taken the view that the saccus is anterior to the vinculum, that what I have labelled as the costa is the valva, that what I have labelled as the lateral process of the sacculus is the sacculus, that what I have labelled as the median process of the sacculus is a posterior process of the vinculum and that the median emargination is in the posterior edge of the vinculum
The main differences between my interpretation of the genitalia and that illustrated in MBGBI is in the junction between valvae and vinculum and in the consequent labelling of the parts of the valvae.
I have taken the view that the saccus is the median component of the vinculum, that the valvae are composed of the fused costa + sacculus, and that the two sacculi are partially fused in the midline at the median emargination. The labelled image of the valvae and vinculum shows a dashed line at the clear junction between valvae and vinculum that results from this interpretation - and this interpretation can be applied to all Lepidopteran families.
MBGBI appears to have taken the view that the saccus is anterior to the vinculum, that what I have labelled as the costa is the valva, that what I have labelled as the lateral process of the sacculus is the sacculus, that what I have labelled as the median process of the sacculus is a posterior process of the vinculum and that the median emargination is in the posterior edge of the vinculum
Female genitalia
Features to note in the female genitalia are:
1) Is the corpus bursae (CB) clearly defined? or is the transition from the ductus bursae (DB) gradual? 2) Is the signum clearly in the CB or in the transition zone between DB and CB? 3) Is the CB oval or spherical? 4) Is the signum on the left or right? 5) Presence and extent of any teeth on the concave surface of the signum. 6) Is the DB straight or curved? 7) Detail of the ventral plate of A8 |
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 |
Page fully revised 01/12/2024
Page fully revised 01/12/2024