Key for the Identification of the Millipedes of the British Isles from Photographs

So here's something I've been working at on-and-off for a while as a bit of a learning exercise. This is my best attempt at a key to the Millipedes of the British Isles from Photographs on iNat. The strategy is in line with other keys I have done for hoverflies: photographs don't give you the opportunity to choose which features you look at, and are often short on detail, so the key tries to deploy the most obvious features first, and where possible to include a number of different features. In addition, for iNat purposes it is helpful to try and follow the taxonomy step by step from the broader IDs down to species level, enabling the finest possible ID to be given - this is often not possible, but an attempt has been made. These two strategies can sometimes conflict, so compromises have to be made.

Of course certain species simply cannot be identified without microscopic treatment and therefore the key sometimes ends at a higher level (where it is not obvious I have listed the possible taxa in a footnote marked e.g. '(1)'). I have tried to use features that might just be visible in a high quality macro photograph.

I have not illustrated this key - I might add some pics at some time later, but there isn't much available. However there are pictures of the vast majority of British species on the website of the British Myriapod and Isopod Group www.bmig.org.uk/checklist/millipede-checklist which can be used to help interpret the key.

KEY TO THE ORDERS OF BRITISH MILLIPEDES
1. a. Body covered in obvious tufts of thick feathery setae and tufts of especially long setae extending backwards from the rear; 11 segments; less than 4mm long.
b. Body not covered in such tufts; usually longer.
ORDER POLYXENIDA (Polyxenus lagurus)
SUBCLASS CHILOGNATHA
End

2
2. a. 12 segments (can look like 11); woodlouse-like appearance; can curl into a ball (not a spiral).

b. More than 18 segments.
ORDER GLOMERIDA (Family Glomeridae)
SUBCLASS CHILOGNATHA cont...
8

3
3. a. 19 or 20 segments; often with 'flat-backed' appearance.
b. More than 25 segments.
ORDER POLYDESMIDA
SUBCLASS CHILOGNATHA cont...
12
4
4. a. 26 to 32 segments; head distinctly wider than the segments immediately behind it; may have 'flat-backed' or cylindrical appearance.
b. More than 32 segments; head a similar width to th following segments.
ORDER CHORDEUMATIDA

SUBCLASS CHILOGNATHA cont...
22

5
5. a. Head conical or 'beak-like'.

b. Head rounded.
SUPERORDER COLOBOGNATHA
SUPERORDER JULIFORMA
6

7
6. a. Ocelli present; found outdoors in the British Isles.
b. Ocelli absent; never found outdoors in the British Isles.
ORDER POLYZONIIDA
ORDER SIPHONOPHORIDA
11
End
7. a. Medial suture on the face to the labrum; not found outdoors in the British Isles.
b. Medial suture not extending to the labrum; found outdoors in the British Isles.
ORDER SPIROBOLIDA
ORDER JULIDA
End
34
KEY TO THE ORDER GLOMERIDA (Family Glomeridae)
8. a. Tergites rough and tuberculate; tergites pale or dark.
b. Tergites smooth and pale.
Family Glomeridae cont...
Subfamily Doderiinae
9
10
9. a. Tergites dark with pale borders.
b. Tergites entirely pale.
Glomeris marginata
Geoglomeris subterranea
End
End
10. a. Hind margins of tergites raised into distinct ridges.
b. Tergite hind margins not raised.
Trachysphaera lobata
Adenomeris gibbosa
End
End
KEY TO THE ORDER POLYZONIIDA
11. a. Small thread-like pink/purple millipede not found outside in UK.
b. Broad bodied brown millipede found outside in UK.
Rhinotus purpureus
Polyzonium germanicum
End
End
KEY TO THE ORDER POLYDESMIDA
12. a. Paranota with contrastingly pale colour compared to the main trunk.
b. Paranota of similar colouration to the trunk.
ORDER POLYDESMIDA cont...
SUBORDER POLYDESMIDEA
13
15
13. a. Dark brown millipede, paranota with white-ish tips, white-pointed telson and dark legs.
b. Reddish brown millipede with more orangish paranota.
Chondrodesmus cf riparius
Family Paradoxosomatidae
End
14
14. a. Pale colour restricted narrowly to the edges of the paranota, not found outdoors in the UK.
b. Pale colour in larger squarish patches at the sides of the paranota.
Oxidus gracilis
Stosatea italica
End
End
15. a. Was found outdoors in the British Isles (This is a shortcut - species compatible with the British Isles' climate will key out both ways).
b. Was not found outdoors in the British Isles.
INFRAORDER POLYDESMOIDES

SUBORDER POLYDESMIDEA cont...
16

19
16. a. Tiny translucent/white millipede whose rounded paranota create a 'string-of-beads' appearance.
b. Larger and more robust species whose paranota jut out as flattish ledges.
Family Macrosternodesmidae
Family Polydesmidae
End
17
17. a. 19 segments, small species.
b. 20 segments.
Brachydesmus superus
Family Polydesmidae cont...
End
18
18. a. Pinkish brown millipede with particularly well-rounded paranotal edges in dorsal view in the middle portion, typically found along the M4 corridor.
b. Different.
Propolydesmus testaceus

Genus Polydesmus
End

End
20. a. Paranota extended to the side as 'ledges'.
b. Paranota expanded 'rubber-ring-style'.
Family Polydesmidae
SUBORDER POLYDESMIDEA cont...
17
21
21. a. Tiny translucent/white millipede with 'string-of-beads' appearance found outdoors in UK.
b. Different.
Family Macrosternodesmidae
SUBORDER POLYDESMIDEA (1)
End
End
KEY TO THE ORDER CHORDEUMATIDA
22. a. Paranota laterally prominent in dorsal view.

b. Paranota not laterally prominent in dorsal view, (the segments smoothly cylindrical).
SUBORDER CRASPEDOSOMATIDEA
Family Chordeumatidae
26

23
23. a.Pallid species with ocelli in a flattened triangle, 28 or 30 segments
b. Darker species with ocelli in equilateral triangle, 30 segments.
Genus Melagona
Family Chordeumatidae cont...
24
25
24. a. 28 segments.
b. 30 segments.
Melagona scutellaris
Genus Melagona
End
End
25. a. In side view, male gonopods with large white structures filling the gap between anterior and posterior paragonopods (This area is not obscured by legs).
b. In side view, male gonopods with the gap between anterior and posterior paragonopods visible. (This area is not obscured by legs).
Genus Chordeuma

Orthochordeumella pallida
End

End
26. a. Large orange-brown millipede with paranota extremely well developed, having the appearance of a Polydesmus
b. Paranota less well developed, or colour different.
Nanogona polydesmoides
SUBORDER CRASPEDOSOMATIDEA cont...
End
27
27. a. Sides of the body and the dorsal midline dark - not reaching to the paranota - sides of the dorsum pale.
b. Different.
Ceratosphys amoena confusa
SUBORDER CRASPEDOSOMATIDEA cont...
End
28
28. a. Body unpigmented - very pure white.

b. Colour at least dirty white.
SUBORDER CRASPEDOSOMATIDEA cont...
SUBORDER CRASPEDOSOMATIDEA cont...
29

32
29. a. Body bearing long and stout curved setae.

b. Setae normal.
SUPERFAMILY ANTHROLEUCOSOMATOIDEA
Genus Brachychaeteuma
30

31
30. a. Paranota and cheeks very well developed.
b. Paranota and cheeks not very well developed.
Psichrosoma cf breuili
Cranogona dalensi
End
End
31. a. About 3 poorly pigmented ocelli
b. About 6 well pigmented ocelli
Genus Brachychaeteuma
Brachychaeteuma melanops
End
End
32. a. Body bearing many very long stout setae.
b. Setae much less prominent.
Hylebainosoma nontronensis
SUBORDER CRASPEDOSOMATIDEA cont...
End
33
33. a. Dark brown millipede, paler over the paranotal bumps.
b. Dark brown millipedes without such a pattern.
Craspedosoma rawlinsii
SUBORDER CRASPEDOSOMATIDEA (2)
End
End
KEY TO THE ORDER JULIDA
34. a. Small thread-like millipedes without longitudinal striae on the metazonites; never very dark, sometimes pure white with brightly coloured (red/orange) ozadenes.
b. More robust-shaped millipedes, sometimes large; longitudinal striae on the metazonites; sometimes very dark, always at least dirty white (never pure white); if visible, ozadenes usually dark red/brown, rarely brightly coloured.
ORDER JULIDA cont...

Family Julidae
35

39
35. a. Pure white millipede with brightly coloured (red/orange) ozadenes and without ocelli.
b. At least slightly pigmented and with less bright ozadenes; ocelli present.
Subfamily Blaniulinae
ORDER JULIDA cont...
36
37
36. a. Ozadenes red.
b. Ozadenes orange.
Blaniulus guttulatus
Tribe Boreoiulini (3)
End
End
37. a. Ocelli arranged in a roughly equilateral triangular patch.
b. Ocelli arranged in a narrow horizontal bar.
Family Nemasomatidae
Family Blaniulidae
End
38
38. a. Ocelli arranged in a single row.
b. A couple of ocelli placed higher than the main row so that the ocellar bar appears to widen anteriorly.
Family Blaniulidae (4)
Proteroiulus fuscus
End
End
39. a. Robust dark millipede with pink legs and antennae.
b. Legs and antennae not pink.
Ommatoiulus moreleti
Family Julidae cont...
End
40
40. a. Body with stripes running most of its length (Be aware that immatures of some unstriped species may exhibit vague stripes).
b. Different.
Family Julidae cont...

Family Julidae cont...
41

44
41. a. Dark with narrow pale medial stripe
b. Dark with pale submedial stripes and dark medial stripe.
Leptoiulus belgicus
Family Julidae cont...
End
42
42. a. Robust brown millipede with pale stripes orangeish, and dorsal projection of telson.
b. Smaller millipede, pale stripes not orange.
Ommatoiulus sabulosus
Genus Brachyiulus
End
43
43. a. Found near the Eden project!
b. Found far from the Eden project.
Genus Brachyiulus
Brachyiulus pusillus
End
End
44. a. Pale body with relatively brightly coloured ozadenes, no ocelli. (Beware of Cylindroiulus salicivorus in Edinburgh which is pale with orange ozadenes and just a few poorly pigmented ocelli)
b. Usually more pigmented; ocelli present, ozadenes usually dull or dark coloured if visible.
Family Julidae cont...

Family Julidae cont...
45

46
45. a. Ozadenes orange, telson with dorsal projection.
b. Ozadenes red, telson lacking dorsal projection.
Cylindroiulus vulnerarius
Metaiulus pratensis
End
End
46. a. Telson without dorsal projection.
b. Telson with dorsal projection.
Family Julidae cont...
Family Julidae cont...
47
49
47. a. Hind segment with ploughshare-like forward-pointing ventral projection; not a very dark species.
b. Hind segment with no such projection; dark or pale.
Unciger foetidus
Genus Cylindroiulus
End
48
48. a. Large (>20mm) dark blue-bronze millipede.
b. Small (<20mm) Brown to pale millipede.
Cylindroiulus caeruleocinctus
Genus Cylindroiulus (5)
End
End
49. a. Telson projection club-shaped.
b. Telson projection not club-shaped.
Genus Cylindroiulus
Family Julidae cont...
50
51
50. a. Very large (>>30mm) and very dark millipede.
b. Much smaller (<<30mm) pale pinkish brown millipede.
Cylindroiulus londiniensis
Cylindroiulus puctatus
End
End
51. a. Large very dark millipede with transverse striae on prozonates, and strongly contrasting white legs.
b. Large or small, dark or pale millipede without transverse striae on prozonates
Tachypodoiulus niger
Family Julidae cont...
End
52
52. a. Hind segment with ventral projection.
b. Hind segment without ventral projection.
Family Julidae cont...
Family Julidae cont...
53
55
53. a. Hairs on body arranged in conspicuous fringes on the metazonites and not limited to hind segments.
b. Hairs on body less conspicuous and limited to hind segments.
Enantiulus armatus
Genus Cylindroiulus
End
54
54. a. Large millipede >30mm.
b. Smaller species.
Cylindroiulus apenninorum
Cylindroiulus pyrenaicus
End
End
55. a. Pallid species with orange ozadenes and few, weakly pigmented ocelli.
b. Usually very dark species, if pallid then with a larger patch of well pigmented ocelli.
Cylindroiulus salicivorus
Family Julidae cont...
End
56
56. a. First leg-pair of males broad at base and then distinctly sickle shaped.
b. Females, or males with different first leg pairs.
Genus Ophyiulus
Family Julidae cont...
End
57
57. a. First leg-pair of males tiny, second with flattened projection
b. Females, or males with different first leg pairs.
Julus scandinavius
Family Julidae cont...
End
58
58. a. First leg pair of males swollen, terminally curved as hooks, 2nd legs with basal sheath-like projections.
b. Females, or males with different first leg pairs.
Leptoiulus kervellei
Family Julidae (6)
End
End

(1) Family Haplodesmidae or Poratia digitata
(2) Genera Anthogona, Anamastigona or Turdulisoma
(3) Genera Boreoiulus or Archiboreoiulus
(4) Genera Choneiulus or Nopoiulus
(5) Cylindroiulus britannicus, latestriatus or parisiorum
(6) Genera Haplopodoiulus or Allajulus, or Cylindroiulus dahli or sagittarius

Publicado el marzo 21, 2023 10:10 MAÑANA por matthewvosper matthewvosper

Comentarios

@bmig_steve @szucsich I've had a go at a millipede key (working on centipedes too!). If it's of any interest please take a quick look, hopefully there are no egregious errors!

Publicado por matthewvosper hace 11 meses

@matthewvosper really great, and thanks for sharing - I will try to give it a look, despite my expertise in Diplopoda is limited (but this will help to boost it somewhat). All the best
Nikola

Publicado por szucsich hace 11 meses

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