There are 10 Stenoptilia species on the British list.
S.pneumonanthes is extinct and S.gallobritannidactyla is doubtfully British. These will not be considered further.
S.pneumonanthes is extinct and S.gallobritannidactyla is doubtfully British. These will not be considered further.
The genus is keyed in Hart as:
Forewing with two lobes, hindwing with 3 lobes; 3rd lobe of hindwing without a scale tooth; first forewing lobe pointed; tornus of first forewing lobe indistinct but identifiable.
Forewing with two lobes, hindwing with 3 lobes; 3rd lobe of hindwing without a scale tooth; first forewing lobe pointed; tornus of first forewing lobe indistinct but identifiable.
The last mentioned feature distinguishes Stenoptilia from several genera in which there is no identifiable tornus of the first forewing lobe and from Gillmeria in which the first forewing lobe has a distinct tornus. Gillmeria is better distinguished by its generally ochreous forewings and long labial palps (extending beyond the eyes by 2x the diameter of an eye).
S.islandicus has a restricted distribution in the Scottish Highlands and has a pale grey or fawn forewing (all other species being darker)
Hart keys several features that may help to distinguish the remaining species:
S.pterodactyla has a brown 1st forewing lobe (usually grey or blackish in other species)
S.zophodactylus has an entirely white saddle
S.bipunctidactyla has a white saddle with a brown median line
S.millieridactyla has a white line across the first forewing lobe
S.scabiodactylus and S.annadactlya lack the above features but require genital determination to distinguish from each other.
S.inopinata is not keyed in Hart but he comments that it is plain brownish-grey with a large black spot at the base of the forewing cleft
S.pterodactyla has a brown 1st forewing lobe (usually grey or blackish in other species)
S.zophodactylus has an entirely white saddle
S.bipunctidactyla has a white saddle with a brown median line
S.millieridactyla has a white line across the first forewing lobe
S.scabiodactylus and S.annadactlya lack the above features but require genital determination to distinguish from each other.
S.inopinata is not keyed in Hart but he comments that it is plain brownish-grey with a large black spot at the base of the forewing cleft
Male genitalia: to follow
Female genitalia
All Stenoptilia species have a pair of elongate pointed thorn signa in the corpus bursae; the ductus bursae has a distinct antrum posteriorly and a narrower anterior portion with a sclerotised band. (In the fractions mentioned below I have taken the antrum to be part of the ductus bursae). The species divide fairly distinctly into those with a long antrum (antrum ½ length of ductus bursae) and those with a short antrum (antrum distinctly shorter that ½ length of ductus bursae).
All Stenoptilia species have a pair of elongate pointed thorn signa in the corpus bursae; the ductus bursae has a distinct antrum posteriorly and a narrower anterior portion with a sclerotised band. (In the fractions mentioned below I have taken the antrum to be part of the ductus bursae). The species divide fairly distinctly into those with a long antrum (antrum ½ length of ductus bursae) and those with a short antrum (antrum distinctly shorter that ½ length of ductus bursae).
Species with a short antrum
S.millieridactlya - antrum very short (~⅙ length of ductus bursae), with pointed posterolateral margins and steeply tapering from ostium.
S.annadactyla - antrum ~⅓ length of ductus bursae, parallel-sided, junction with anterior ductus abrupt; dorsal wall extends posteriorly as a rugose tongue.
S.islandica - antrum ~⅓ length of ductus bursae, parallel-sided with a rounded anterior end such that the junction with the ductus is not so abrupt as in S.annadactyla
S.millieridactlya - antrum very short (~⅙ length of ductus bursae), with pointed posterolateral margins and steeply tapering from ostium.
S.annadactyla - antrum ~⅓ length of ductus bursae, parallel-sided, junction with anterior ductus abrupt; dorsal wall extends posteriorly as a rugose tongue.
S.islandica - antrum ~⅓ length of ductus bursae, parallel-sided with a rounded anterior end such that the junction with the ductus is not so abrupt as in S.annadactyla
Species with a long antrum
S.zophodactylus - antrum broad at ostium, gradually tapering; dorsal wall of antrum extending posteriorly to a midline point
S.bipunctidactyla - antrum gradually tapering. 1. The antrum of S.bipunctidactyla appears distinctly narrower than that of S.zophodactylus but I need to examine more material to provide an absolute distinction; 2. The dorsal wall of the antrum extends posteriorly as a rounded "tongue" in the images at Moth Dissection, but this is not illustrated in Hart; 3. Hart comments and illustrates one side of the antrum as fairly straight and the other side as distinctly curved; this distinction is not so clear on the images at Moth Dissection and in Hart's illustrations the curved side is on the right while, to the extent that a distinction is visible, the curved side is on the left in the images at Moth Dissection.
S.inopinata - antrum narrow tapered; dorsal wall extends posteriorly as a rugose plate that narrows to a midline point; anterior ductus bursae strongly curved.
S.scabiodactylus - antrum broad, only slightly tapered
S.pterodactyla - antrum more-or-less parallel-sided, possibly broader midway along its length than at level with anterior margin of A8.
S.zophodactylus - antrum broad at ostium, gradually tapering; dorsal wall of antrum extending posteriorly to a midline point
S.bipunctidactyla - antrum gradually tapering. 1. The antrum of S.bipunctidactyla appears distinctly narrower than that of S.zophodactylus but I need to examine more material to provide an absolute distinction; 2. The dorsal wall of the antrum extends posteriorly as a rounded "tongue" in the images at Moth Dissection, but this is not illustrated in Hart; 3. Hart comments and illustrates one side of the antrum as fairly straight and the other side as distinctly curved; this distinction is not so clear on the images at Moth Dissection and in Hart's illustrations the curved side is on the right while, to the extent that a distinction is visible, the curved side is on the left in the images at Moth Dissection.
S.inopinata - antrum narrow tapered; dorsal wall extends posteriorly as a rugose plate that narrows to a midline point; anterior ductus bursae strongly curved.
S.scabiodactylus - antrum broad, only slightly tapered
S.pterodactyla - antrum more-or-less parallel-sided, possibly broader midway along its length than at level with anterior margin of A8.
