Nemapogon identification
There are 9 species on the British list. Some are readily identifiable on external features, some require genital determination.
All are small with a forewing length of 5-8mm; N.picarella is a little larger with a forewing length 6-9.5mm
All have fungi as their larval food and all have a woodland habitat.
At the time of writing, N.picarella is confined to Scotland, N.falstriella is confined to North Essex, there has only been one British record of N.inconditella (Devon, 1979) and the only other species to occur in Scotland are N.cloacella and N.granella.
Some segregation can be based on head colour:
Head white:
N.clematella and N.picarella have extensive white areas of the forewing. N.clematella has an angulate black median fascia, more or less broken at the angle; N.picarella has a black streak from base to apex and several bold black spots.
Nemapogon clematella
|
N.variatella and N.inconditella have a white forewing with a variable amount of black marking, including a partial median fascia extending from the costa to midwing. These two require genital determination
Nemapogon variatella
|
Head black & white
N.falstriella has a black vertex and white frons and a predominently blackish forewing, which distinguish it from all other Nemapogon spp.
N.falstriella has a black vertex and white frons and a predominently blackish forewing, which distinguish it from all other Nemapogon spp.
Nemapogon falstriella
|
Head ochreous
N.granella, N.cloacella, N.koenigi and N.ruricolella have ochreous heads. The actual colour ranges from pale whitish-ochreous to distinctly ochreous. N.cloacella is by far the commonest and most widespread member of the genus. N.cloacella, koenigi and ruricolella all usually show a white spot in the distal half of the forewing, level with the tornus; N.granella may be suspected from the absence of this spot. N.ruricolella may be suspected from a general scattering of golden-brown scales. None of these species can be identified with certainty without genital determination.
N.granella, N.cloacella, N.koenigi and N.ruricolella have ochreous heads. The actual colour ranges from pale whitish-ochreous to distinctly ochreous. N.cloacella is by far the commonest and most widespread member of the genus. N.cloacella, koenigi and ruricolella all usually show a white spot in the distal half of the forewing, level with the tornus; N.granella may be suspected from the absence of this spot. N.ruricolella may be suspected from a general scattering of golden-brown scales. None of these species can be identified with certainty without genital determination.
Nemapogon cloacella
|
Nemapogon koenigi
|
Nemapogon ruricolella
|
Male genitalia
Preparation note: The most important diagnostic differences occur in features of the gnathos arms and at the apex of the sacculus. These features may be obscured in an unmanipulated preparation in ventral view. A better idea of the overall structure of the genitalia can be better seen in lateral view. The valvae and gnathos may be best displayed by either folding the valvae anteriorly or by separating the vinvulum-tegumen ring and presenting the valvae and tegumen separately. The gnathos arms are angular. In the set specimen they have lateral and medial components with an "elbow" at their junction. (In the natural position the lateral component is dorsal and in the long axis of the genitalia, and the medial section extends ventrally from the "elbow"; it turns medially when the specimen is set).
Preparation note: The most important diagnostic differences occur in features of the gnathos arms and at the apex of the sacculus. These features may be obscured in an unmanipulated preparation in ventral view. A better idea of the overall structure of the genitalia can be better seen in lateral view. The valvae and gnathos may be best displayed by either folding the valvae anteriorly or by separating the vinvulum-tegumen ring and presenting the valvae and tegumen separately. The gnathos arms are angular. In the set specimen they have lateral and medial components with an "elbow" at their junction. (In the natural position the lateral component is dorsal and in the long axis of the genitalia, and the medial section extends ventrally from the "elbow"; it turns medially when the specimen is set).
|
|
|
|
|
Left 3 images N.koenigi: unmanipulated ventral view, unmanipulated lateral view, valvae folded anteriorly
Right 2 images N.cloacella: valvae+aedagus, tegumen
Right 2 images N.cloacella: valvae+aedagus, tegumen
|
N.cloacella
a: the medial section of the gnathos is narrower and slightly shorter than the lateral section and has a distinct kink posteriorly towards its apex. b: the apex of the sacculus is obliquely truncate with the lateral margin extending further than the medial margin. c: the juxta has a medial notch |
|
|
N.koenigi
a: the medial section of the gnathos is narrower and longer than the lateral section and is smoothly curved towards its apex. b: the apex of the sacculus is evenly rounded. c: the juxta is evenly domed |
|
|
N.ruricolella
a: the medial section of the gnathos is narrower and distinctly longer than the lateral section and is straight apart from a slight kink posteriorly near its apex. b: the apex of the sacculus is slightly produced c: the juxta has a medial notch |
|
|
N.granella (no material)
a: the medial section of the gnathos is as broad as and distinctly longer than the lateral section and has a rounded apex b: the apex of the sacculus is concave with the lateral end of the concavity produced into a point c: the juxta has a medial notch |
|
N.variatella
a: the medial section of the gnathos is narrower and longer than the lateral section and has a fimbriate apex b: the apex of the sacculus is distinctly produced into a point |
|
|
N.inconditella (no material)
a: the medial section of the gnathos is narrower and longer than the lateral section and is evenly tapered from base to apex b: the apex of the sacculus is evenly tapered into a point |
|
N.clematella (no material)
a: the medial section of the gnathos is as broad as and distinctly longer than the lateral section and is straight apart from a curve at its apex b: the apex of the sacculus is produced into a broad dome |
|
N.picarella (no material)
a: the medial section of the gnathos is as narrower and longer than the lateral section and is straight with a hooked apex b: the apex of the sacculus is produced into a narrow point The aedeagus also appears to be unique amongst Nemapogon species in being extremely long with a series of small apical cornuti |
|
N.falstriella
a: the lateral section of the gnathos is very broad and rounded and the medial section very narrow and straight b: the apex of the sacculus is produced into a broad point The uncus lobes are also noticeably more robustly setose than in other Nemapogon species |
|
Female genitalia:
Illustrated in MBGBI2 (p176) and shown at Moth Dissection, but neither source clearly describes or indicates the key distinguishing features. The account below is also hampered by limited material and should be regarded as to some extent propositional and provisional. In particular I am uncertain whether the sclerotisation patterns appearing on the ventral surface of A8 are in the ventral lamina of A8 or in the antrum.
The main differences illustrated in MBGBI2 are in the shape of A8 and the periostial sclerotisations.
Illustrated in MBGBI2 (p176) and shown at Moth Dissection, but neither source clearly describes or indicates the key distinguishing features. The account below is also hampered by limited material and should be regarded as to some extent propositional and provisional. In particular I am uncertain whether the sclerotisation patterns appearing on the ventral surface of A8 are in the ventral lamina of A8 or in the antrum.
The main differences illustrated in MBGBI2 are in the shape of A8 and the periostial sclerotisations.
|
N.cloacella
A8 elongate Posterior edge of ventral lip of ostium with a midline protrusion |
|
N.koenigi (no material)
A8 quadrate or slightly transverse Posterior edge of ventral lip of ostium straight However, images at Moth Dissection show some protrusion of the ventral lip |
|
N.ruricolella
Distinctive pattern of sclerotisation of ventral lamina of A8 / antrum |
|
N.granella (no material)
Ventral lip of ostium strongly thickened with a rounded anterior margin and a slight protrusion of the posterior margin |
|
N.variatella
Strongly sclerotised ventral plate of A7 with ostium in a notch in its posterior margin |
|
N.inconditella (no material)
Antrum an angular funnel |
|
N.clematella
Ventral surface of antrum with a digitate ventral process |
|
N.picarella
Distinctive pattern of sclerotisation of ventral lamina of A8 / antrum |
|
N.falstriella
Ostium at the posterior margin of A8, with a scalloped ventral lip. |
|
Page published 07/11/2024
