Provisional key to Tribe: Trifurculini (Trifurcula, Bohemannia, Ectoedemia) males
Collar with lamellate scales: Stigmella (fascia usually postmedian) and Bohemannia quadrimaculella and B.auriciliella
Collar with hair scales: Ectoedemia (fascia if present usually median) and Bohemannia pulverosella
Trifurcula species have at least two types of forewing scales and a 'velvet' patch of usually yellow androconial scales on hindwing underside

In the tables below: fw=forewing length (mm), ws=wingspan (mm), ant=number of antennal segments; colour of collar may be described in relation to colour of frontal tuft eg "paler"; hair-pencil when present is on hindwing; valva has a pointed apex unless otherwise stated
A) Species with an unmarked forewing
 
fw
ws
ant
frontal tuft
collar
spots
hair pencil
other
B.pulverosella
  
6.2-7.5
34-38
orange
yellow-orange
absent
absent?
costal bristles
T.cryptella
 
~5
 
ochreous-ferruginous
paler
absent*
absent
 
T.subnitidella
2.0-2.6
 
31-36
yellow-ochreous-fuscous
concolorous
absent
absent
 
T.immundella
 
6.0-8.2
35-43
whitish - ferruginous-fuscous
yellow-white
absent
absent
 
T.beirnei
 
8.0-9.0
 
yellow-orange
yellow-white
absent
absent
 
T.squamatella
 
7.8-9.8
46-55
yellow-white to yellow-orange
paler
absent
absent
 
Z.atrifrontella
2.9-3.2
 
45-53
brown-black
brown-black
absent
white
thorax whitish
Z.longicaudella
2.7-3.6
 
41-50
brown-black
brown-black
absent
yellow-brown
thorax brown
Z.amani
3.2-3.9
 
36-41
orange-ochreous
orange-ochreous
absent
white, long
hp ⅓ fw
*MBGBI1 mentions that T.cryptella may have a pale tornal (ie postmedian dorsal) spot; Nepticuloidea.info states that it has a costal spot
B) Species with a dorsal pale spot only
 
fw
ws
as
ft
c
sf
hp
other
E.intimella
2.4-2.8  
 
39-45
ferruginous to yellowish
ferruginous to yellowish
median dorsal
ochreous
antennae pale
E.heringella
2.1-2.7
 
35-42
yellow-white to orange
yellow-white
median dorsal
absent
costal bristles,
​white costal scales*
F.septembrella**
 
 
 
ferruginous
whitish
postmedian dorsal
?
antennae dark
* E.heringella has an elongate patch of brown androconial scales on the forewing underside.
** Stigmella catharticella is very similar to F.septembrella - S.catharticella has long hindtibial hairs and dark-spotted tarsi; F.septembrella has short tibial spines and unspotted tarsi (MBGBI1)
C) Species with both costal and dorsal pale spots, without a complete fascia
E.argyropeza is parthenogenetic (females only)

Spots postmedian; 50-57 antennal segments, apical 11-12 antennal segments contrastingly white, ws 7.4-8.5mm: B.quadrimaculella
Spots postmedian; ~44 antennal segments, ws 6mm: B.auriciliella
Frontal tuft and collar dark ferruginous-fuscous/ochreous, spots postmedian, yellow androconial scales on hw underside: T.headleyella/T.eurema
Frontal tuft and collar black; median dorsal, antemedian costal and postmedian discal: E.quinquella
Frontal tuft and collar black; median dorsal, median costal variable antemedian spots and white scales: E.turbidella
Frontal tuft yellow/orange/ferruginous; collar concolorous; large antemedian costal and smaller postmedian dorsal spots: E.weaveri
Frontal tuft yellow/orange/ferruginous; collar concolorous; no basal spots, no hair-pencil: E.albifasciella
Frontal tuft yellow/orange/ferruginous; collar concolorous; variable basal spots, yellowish-white hair-pencil: E.turbidella/hannoverella*
* in E.turbidella the ventral margin of the valva is concave and the apex demarcated as a point; in E.hannoverella the ventral margin straight and there is no apical point 
Frontal tuft yellow/orange/ferruginous; collar brown-black, basal spot: E.heringi/subbimaculella**
** these may not be separable but in E.subbimaculella the apex of the rounded tegumen is slightly more produced, the ventral margin of the valva is more serrate and the apex more pointed than in E.heringi
 
fw
ws
ant
frontal tuft
collar
spots±
hair pencil
other
B.quadrimaculella
  
7.4-8.5
50-57*
orange-ferruginous
shining fuscous
pm c&d
dark brown, short
hp ⅙ fw
B.auriciliella
 
~6
~44
orange
coppery fuscous
pm c&d §
absent
spots almost fasciate
T.headleyella
 
5.0-5.8
35-41
dark ferruginous-fuscous
dark ferruginous-fuscous
pm c&d, metallic
absent?
 
T.eurema
 
6.0-8.0
 
ferruginous-ochreous
ferruginous-ochreous
pm c&d
absent
spots sometimes fasciate
E.weaveri
 
8.0-9.0
 
yellow-orange
yellow-white
c large am
​d small pm
?
 
E.albifasciella
2.3-3.0
 
34-41
orange-ferruginous
orange-ferruginous
c am, d m
absent
costal bristles
E.heringi
1.9-2.4
 
29-32
ferruginous
brown-black
b, c am, d m
absent
costal bristles
E.subbimaculella
2.2-2.8
 
31-36
yellow-orange
dark brown
b, c am, d m
absent
costal bristles
E.quinquella
1.8-2.3
 
36-42
black
black
c am, d m, di pm 
yellowish
 
E.hannoverella
2.4-3.2
 
44-53
yellow-orange-ferruginous
sl. paler
c m, d m**
yellowish-white
 
E.turbidella
2.4-3.2
 
44-53
black or ​yellow-orange-ferruginous
sl. paler
c m, d m**
yellowish-white
 
E.argyropeza
 
 
 
 
 
 
 
FEMALES ONLY
± b = basal, pm=postmedian, m= median, am=antemedian, c=costal, d=dorsal, di=discal
* Apical 11-12 segments contrastingly white
​§ Dorsal spot extended proximally along dorsum
​** variable, ​sometimes fused, sometimes antemedian discal, basal dorsal
 
pseuduncus
central element of gnathos
valva±
other
B.quadrimaculella
absent, tegumen truncate  
very long, narrow
abruptly narrowed in apical half
 
B.auriciliella
absent, tegumen rounded
long, narrow
vm concave?
uncus band-like with lateral setose pads
T.headleyella
tegumen pointed or truncate
large, rounded
triangular
uncus pointed
T.eurema
pointed
rounded
vm convex
uncus bifurcate
E.weaveri
 
 
 
 
E.albifasciella
triangular, apex rounded
parallel-sided, apex truncate
serrate, dm strongly convex*
 
E.heringi
rounded
short, broad, rounded
vm straight in proximal ⅓ then concave, apex blunt
 
E.subbimaculella
rounded
tapered to a rounded apex
somewhat serrate
 
E.quinquella
absent, tegumen indented
bifurcate
vm concave
 
E.hannoverella
absent, tegumen wide, rounded
long with ventral spines
vm straight, dm strongly convex, no apical point
 
E.turbidella
absent, tegumen rounded
ttriangular
vm concave
 
E.argyropeza
 
 
 
FEMALES ONLY
± vm=ventral margin, dm=dorsal margin
* Nepticuloidea.info states that the "inner margin" (which I interpret as the ventral margin) is strongly convex; the image at Dissection Group clearly shows the dorsal margin to be strongly convex. The serrate appearance of the ventral margin of these species is due to prominent sockets of setae.
D) Species with a complete median fascia, without other pale spots
Frontal tuft and collar black; pseuduncus truncate: E.rubivora
Frontal tuft and collar black; pseuduncus long pointed: E.occultella/minimella*
Frontal tuft yellow/ferruginous; collar paler, hair-pencil absent: E.erythrogenella
Frontal tuft yellow/ferruginous; collar concolourous, hair-pencil white: E.angulifasciella
Frontal tuft yellow/ferruginous; collar dark; hair-pencil absent / pseuduncus pointed: E.agrimoniae
Frontal tuft yellow/ferruginous; collar dark; hair-pencil brown / pseuduncus truncate: E.spinosella
Frontal tuft yellow/ferruginous; collar dark; hair-pencil white / pseuduncus truncate: E.atricollis/arcuatella**
*E.occultella has a small elongate patch of narrow white scales along the costa of the forewing underside; absent in E.minimella
** May be separable on size but there is overlap
 
fw
ws
ant
frontal tuft
collar
fascia
hair pencil
other
E.agrimoniae
2.3-3.0  
 
35-41
ferruginous-brown
grey-brown
yellow-silver
absent
fascia constricted in middle
E.angulifasciella
1.9-2.7
 
29-35
pale ochreous-ferruginous
concolorous
oblique, metallic
white
 
E.arcuatella
1.8-2.3
 
24-28
yellow-ferruginous mixed fuscous
fuscous-black
oblique, metallic
white
 
E.atricollis
2.1-2.6
 
29-39
orange-ferruginous
dark fuscous-black
oblique, metallic
white
 
E.minimella
2.3-2.7
  
35-42
black
black
broad, transverse, dull white
?
fascia sometimes constricted in middle
E.occultella
2.3-3.5
 
31-42
black, mixed fuscous-ferruginous
black
broad, transverse, dull white
white
fascia often constricted in middle
E.rubivora
2.0-2.6
 
25-31
black
black
oblique, metallic
white
 
E.spinosella
1.4-2.2
 
24-30
orange
fuscous
silvery
brown
fascia sl. concave to base
E.heckfordi*
 
4.8-6.2
 
ferruginous
?
 
 
 
E.erythrogenella
1.8-2.3
 
33-41
ferruginous-orange
yellow-white
costal portion antemedian
absent
 
* From Wickipedia: discovered 2004 and only known from Devon; genital images available. Leaf-mine on oak
 
pseuduncus
central element of gnathos
valva±
E.agrimoniae
pointed
pointed
widest at base, constricted preapically
E.angulifasciella
truncate
bifurcate
vm sinuate, preapical bulge
E.arcuatella
truncate
bifurcate?
vm straight
E.atricollis
truncate
bifurcate?
vm straight
E.minimella
long, pointed
narrow, truncate  
vm ~straight, dm strongly convex
E.occultella
long, pointed
broad, blunt
vm ~straight, dm strongly convex
E.rubivora
truncate
bifurcate
vm straight
E.spinosella
broad, trunctae
short, rounded
vm ~straight
E.heckfordi*
 
 
 
E.erythrogenella
sl. truncate
broadly spatulate
vm straight
​± vm=ventral margin, dm=dorsal margin
E) Species with a broad complete antemedian fascia and postmedian costal and dorsal spots
= subgenus Etainia: E.sericopeza, E.louisiella, E.decentella
​Refs: Nepticuloidea.info, MBGBI1