Generic features: Ocelli absent in O.unicolorella/atrella/immaculatella; present in O.wilkella; Scape without pecten; O.wilkella has a singe pecten scale; Labial palps long, slender, S2 slightly thickened with appressed scales, S3=S2 in length; Forewing V7&8 stalked, V2,3&4 separate; V6 obsolete in O.wilkella; Male genitalia with small valvae, cylindrical tegumen with weak uncus; Female genitalia with subtriangular signum
Key to species of Oxypteryx |
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Forewing with one or more silver fasciae |
O.wilkella |
Forewing unmarked bronzy-fuscous |
O.unicolorella |
Forewing dark fuscous with a distinct pale tornal spot Pale flecks at base of costal cilia distal to pale costal spot Labial palps ochreous contrasting with fuscous antenna |
O.atrella |
Forewing dark fuscous without a distinct pale tornal spot May have pale flecks at base of costal cilia distal to pale costal spot Labial palps fuscous not contrasting with antenna |
O.immaculatella (also see Aproaerema anthyllidella) |
Identification of species: Although the key makes it seem that identification of these species should be relatively straightforward task, in reality, until considerable experience is gained, only O.wilkella is sufficiently distinct to be readily identifiable on external features. O.unicolorella can only be identified from the key when you know that it belongs to genus Oxypteryx and this is likely to require genital dissection to confirm, as it appears similar to some other poorly marked dark Gelechiids. O.atrella, O.immaculatella and Aproaerema anthyllidella are all very similar.
All web images show O.atrella with, and O.immaculatella without, a distinct pale tornal spot; however this feature is not used in the key in MBGBI4.2 and may be variable in both species. The tornus of O.immaculatella is described as usually "showing a few yellowish white scales". The key uses features of the labial palps "ochreous" in O.atrella and "greyish or yellowish white above and at sides, lower edge dark fuscous" in O.immaculatella. A wider size range is quoted for O.immaculatella (ws 8-13mm) than for O.atrella (11-13mm) so that small specimens (fw<5.0mm) should be O.immaculatella. O.immaculatella also has a longer flight period from May to Sep, while O.atrella is only found in Jul-Aug.
A.anthyllidella is distinguished in MBGBI4.2 on features of the the antennal scape "lined buffish fuscous anteriorly" - however it may be difficult to say with certainty that there is no buff on the antennal scape of the Oxypteryx species and I doubt that this can be used as a reliable feature. The antennal flagellum is entirely dark fuscous in both Oxypteryx species while in Aproaerema it is ringed buff at least in the basal portion - this seems to provide a more reliable distinction. The forewing of Aproaerema shows a dark line around the apex, though this may be lost or less distinct with wear; there is no such line in the Oxypteryx species. In the male, the genitalia protrude from the abdomen in Aproaerema but are completely withdrawn in Oxypteryx.
All web images show O.atrella with, and O.immaculatella without, a distinct pale tornal spot; however this feature is not used in the key in MBGBI4.2 and may be variable in both species. The tornus of O.immaculatella is described as usually "showing a few yellowish white scales". The key uses features of the labial palps "ochreous" in O.atrella and "greyish or yellowish white above and at sides, lower edge dark fuscous" in O.immaculatella. A wider size range is quoted for O.immaculatella (ws 8-13mm) than for O.atrella (11-13mm) so that small specimens (fw<5.0mm) should be O.immaculatella. O.immaculatella also has a longer flight period from May to Sep, while O.atrella is only found in Jul-Aug.
A.anthyllidella is distinguished in MBGBI4.2 on features of the the antennal scape "lined buffish fuscous anteriorly" - however it may be difficult to say with certainty that there is no buff on the antennal scape of the Oxypteryx species and I doubt that this can be used as a reliable feature. The antennal flagellum is entirely dark fuscous in both Oxypteryx species while in Aproaerema it is ringed buff at least in the basal portion - this seems to provide a more reliable distinction. The forewing of Aproaerema shows a dark line around the apex, though this may be lost or less distinct with wear; there is no such line in the Oxypteryx species. In the male, the genitalia protrude from the abdomen in Aproaerema but are completely withdrawn in Oxypteryx.
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O.atrella (left) and O.immaculatella (right)
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Male genitalia: Aproaerema is readily separable - it has a well-developed bilobed uncus and a narrow aedeagus. Features for separating O.atrella and O.immaculatella are as follows (but in well-marked specimens external features are easier to use once the genus has been confirmed):
1) Cornuti. Drawings in MBGBI4.2 (figs 2c & 2d) show the main difference between O.atrella/immaculatella as being the arrangement of minute spicules near the apex of the aedeagus. In O.atrella these are drawn as a patch of numerous overlapping relatively large spicules; in O.immaculatella the spicules are much smaller (~1/6 the length of those in O.atrella) and positioned in rows that do not overlap. So far I have found that with photography at 90x magnification individual spicules can be seen in O.atrella, but remain unresolved in O.immaculatella.
2) Valva. The apex of the valva is distinctly angular in O.immaculatella, somewhat rounded in O.atrella. This distinction may be easiest to see by viewing the outer side of the valva in lateral view. Both species have a subapical flap on the inner surface which may affect perception of the shape of the apex; and the genitalia are shaped so that it is impossible to make a slide specimen in the "set" position without considerable distortion.
Images at Moth Dissection also imply that the uncus of O.atrella is longer and the saccus broader than in O.immaculatella but I have not found these features to be reliable.
1) Cornuti. Drawings in MBGBI4.2 (figs 2c & 2d) show the main difference between O.atrella/immaculatella as being the arrangement of minute spicules near the apex of the aedeagus. In O.atrella these are drawn as a patch of numerous overlapping relatively large spicules; in O.immaculatella the spicules are much smaller (~1/6 the length of those in O.atrella) and positioned in rows that do not overlap. So far I have found that with photography at 90x magnification individual spicules can be seen in O.atrella, but remain unresolved in O.immaculatella.
2) Valva. The apex of the valva is distinctly angular in O.immaculatella, somewhat rounded in O.atrella. This distinction may be easiest to see by viewing the outer side of the valva in lateral view. Both species have a subapical flap on the inner surface which may affect perception of the shape of the apex; and the genitalia are shaped so that it is impossible to make a slide specimen in the "set" position without considerable distortion.
Images at Moth Dissection also imply that the uncus of O.atrella is longer and the saccus broader than in O.immaculatella but I have not found these features to be reliable.
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Oxypteryx atrella
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Oxypteryx immaculatella
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Female genitalia: Aproaerema has a short unsclerotised ductus bursae and no signum. Eulamprotes species show a long sclerotised ductus bursae and a signum in the bursa copulatrix
