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

In addition to the Millipede Key I've also been working on a Centipede Key - so here it is! As with the millipedes, the strategy is to deploy the most obvious features first, and where possible to include a number of different features, and in addition 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.

To my tremendous surprise I have ended up keying out every British species, although it will not allow the confident identification of every species in every combination of habitat and leg count: the Geophilus flavus/seurati/osquidatum group is particularly knotty (there are also a couple more species of very doubtful presence in the UK that I have ignored such as Schendyla monoeci). There are a few species that key out in two or even three places (L. borealis). I have tried to use features that might just be visible in a high quality macro photograph from above or the side - very rarely have I included a ventral feature. It is worth noting however that in practice most photographs will not be identifiable to species, especially in Cryptops.

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/centipede-checklist which can be used to help interpret the key. The key also draws heavily on information in Tony Barber's AIDGAP guide.

After the key are a couple of charts illustrating the trunk length of Geophilomorph species and the antennal length of Lithobiomorph species.

KEY TO THE ORDERS OF BRITISH CENTIPEDES
1. a. 35-101 leg pairs (even in juveniles).
b. 21 or 15 leg pairs, juveniles may have fewer, it is not uncommon for legs to be snapped off - especially the hind legs which should point backwards.
ORDER GEOPHILOMORPHA
CLASS CHILOPODA cont...
29
2
2. a. 21 leg pairs (even in juveniles)

b. 15 leg pairs, juveniles may have fewer.
ORDER SCOLOPENDROMORPHA (Subgenus Cryptops (Cryptops))
CLASS CHILOPODA cont...
4

3
3. a. Legs exceptionally long and spindly, even more so towards the back (some over half the length of the body), tergites of a similar length, body with three longitudinal dark stripes.
b. Legs not exceptionally long and spindly, always less than half the body length, tergites 1-7 and 8-15 alternating long and short (7+8 are both long), body without three longitudinal dark dorsal stripes..
ORDER SCUTIGEROMORPHA (Scutigera coleoptrata)
ORDER LITHOBIOMORPHA
End

6
KEY TO THE ORDER SCOLOPENDROMORPHA (Subgenus Cryptops (Cryptops))
4. a. Head with complete longitudinal sutures, X-shaped suture on T1, very large (up to nearly 50mm), no groove on the underside of the hind prefemur.
b. Head sutures incomplete or absent, no X-suture on T1, hind prefemur with or without a distinct longitudinal groove, <40mm.
Cryptops anomalans

Subgenus Cryptops (Cryptops) cont..
End

5
5. a. Head with short sutures at front and back, no ventral groove in hind prefemur
b. No head sutures, ventral longitudinal groove in hind prefemur.
Cryptops parisi
Cryptops hortensis
End
End
KEY TO THE ORDER LITHOBIOMORPHA
6. a. Very small - 4-11mm, 0 or 1 ocellus each side (but there may be a darkened patch around the ocelli), 24-29 antennal articles, legs without spines, tergites without posterolateral projections.
b. Mainly larger species, at least 3 ocelli per side and usually many more, legs with spines (very rarely without spines but then hind legs greatly thickened), 20-54 antennal segments, some tergites with or without projections.)
Genus Lamyctes

Genus Lithobius
7

9
7. a. Chestnut colour, one ocellus each side surrounded by a large black patch, 7-10mm, 25-29 antennal articles, unlikely to be found outdoors.
b. Chestnut or pallid colour, one ocellus each side, 4-11mm, 24-25 antennal articles, ocelli not surrounded by a large black patch.
Lamyctes africanus

Subgenus Lamyctes (Lamyctes)
End

8
8. a. Chestnut colour, one ocellus each side, up to about 11mm, 25 antennal articles, likely to be found outdoors.
b. Pallid colour, no ocelli, up to about 5mm only, 24 antennal articles, unlikely to be found outdoors.
Lamyctes coeculus
Lamyctes emarginatus
End
End
9. a. Legs with obvious dark banding, tergites with a distinctive marbled pattern, (tergite projections on T7,9,11 and 13, 35-46 antennal articles).
b. Legs and tergites without such a pattern, (no other species has tergite projections on T7).
Lithobius variegatus

Genus Lithobius cont...
End

10
10. a. Trunk pale, sometimes greyish, with a darker midline, head usually a more yellowish colour against which the dark eye patches stand out, projections on at least T11, 13.
b. Colouration different, or if pale with a dark stripe then no tergite projections
Subgenus Lithobius

Genus Lithobius cont...
11

12
11. a. Trunk pale, usually greyish, 17mm, projections on T9, 11 and 13, 32-42 antennal segments, no accesory spine between VpP15 and DpP15.
b. Trunk usually more chestnut coloured, 12/13mm, projections on T11 and 13 only but not on T9 except somewhat noticeably in northern specimens, 28-34 antennal segments, accesory spine between VpP15 and DpP15.
Lithobius melanops

Lithobius borealis
End

End
12. a. Small species, a little over 10mm, 20 antennal segments, no tergite projections, tarsi and metatarsi fused on legs 1-11.

b. Mostly larger species, >20 antennal segments, tarsi and metatarsi not fused, tergites with projections or not.
Subgenus Lithobius (Monotarsobius)
Genus Lithobius cont...
13

14
13. a. Broad projection on posterolateral apex of the hind tibia of males, 6-9 Ocelli arranged with two large posterior ocelli side by side and an 'incomplete rosette' in front of them (appearance of tapering posteriorly).
b. No such hind leg projection in males, 9-13 with one larger posterior ocellus and the others arranged in about 4 columns of three posteriorly and 2 anteriorly (impression of narrowing anteriorly)).
Lithobius curtipes

Lithobius crassipes
End

End
14. a. Small species with characteristic body shape tapering towards the head, and thickened hind four legs giving the appearance of a Cryptops. 23-27 antennal articles, no tergite projections.
b. Larger species with at least 26 antennal articles, body shape and hind legs different.
Lithobius microps

Subgenus Lithobius (Lithobius)
End

15
15. a. No tergite projection on T9.

b. Tergite projection on T9.
Subgenus Lithobius (Lithobius) cont...
Subgenus Lithobius (Lithobius) cont...
16

22
16. a. No tergite projections on T11 or 13

b. At least with tergite projections on T13.
Subgenus Lithobius (Lithobius) cont...
Subgenus Lithobius (Lithobius) cont...
17

20
17. a. Tiny species (8mm), tergites with wrinkled appearance, chestnut colour, 23-34 antennal articles. (usually does have projections on T11 and 13 but keys out here because they may be indistinct).
b. Dark or pale species, tergites not with wrinkled appearance, larger, about 15mm, 33-50 antennal articles).
Lithobius lapidicola

Subgenus Lithobius (Lithobius) cont...
End

18
18. a. Pale species, may have a darker stripe, rare and Scottish, 33-50 antennal articles, head not distinctly wider than trunk, tergites not 'wrinkled'.
b. Darker species,26-50 antennal articles, may have an enlarged head.
Lithobius lucifugus

Subgenus Lithobius (Lithobius) cont...
End

19
19. a. Dark species, enlarged head, especially in males, much broader than the trunk. Males without a distinct projection on the inside apex of the hind tibia, 39-50 antennal articles, 10-14 ocelli arranged in a forward pointing triangle.
b. Head not enlarged, males with or without a dictinct apical projection on the inside of the hind femur, 6-9 ocelli arranged as a rosette with two larger ocelli positioned side by side posterodorsally to the rosette.
Lithobius muticus

Lithobius calcaratus
End

End
20. a. Very large species (35mm) hind legs nearly half the body lenth, 29-34 antennal articles, evenly coloured.
b. very small species 8-13mm, hind legs in normal proportion to the body, 26-34 antennal articles, often with a darker medial line.
Lithobius pilicornis
Subgenus Lithobius (Lithobius) cont...
End
21
21. a. Tiny species (8mm), tergites with wrinkled appearance, chestnut colour, 23-34 antennal articles, tergite projections may be indistinct, without a hint of a projection on T9, no accesory spine between VpP15 and DpP15.
b. 12/13mm, tergites without 'wrinkled' appearnace, may be a hint of a projection on T9 especially in northern specimens, 28-34 antennal segments, accesory spine between VpP15 and DpP15.
Lithobius lapidicola

Lithobius borealis
End

End
22. a. Larger species (>20mm), prominent projections, 35-54 antennal segments.

b. Smaller species (<20mm), more or less prominent projections, 36-45 antennal segments
Subgenus Lithobius (Lithobius) cont...
Subgenus Lithobius (Lithobius) cont...
23

25
23. a. Found in only one location in Sheerness (Kent), projections on T11 and 13 distinctly narrower than those on T9, 38-52 antennal segments.
b. More widespread or very ubiquitous species, tergite projections not distinctly narrower on T11 and 13, 35-54 antennal segments.
Lithobius peregrinus

Subgenus Lithobius (Lithobius) cont...
End

24
24. a. Rare, southern species, 49-54 antennal segments, 11-16 ocelli.
b. Completely ubiquitous, 35-43 antennal segments, 20-30 ocelli.
Lithobius piceus
Lithobius forficatus
End
End
25. a. Very prominent tergite projections, 39-45 antennal segments.

b. Small and narrow projections, 28-45 antennal segments
Subgenus Lithobius (Lithobius) cont...
Subgenus Lithobius (Lithobius) cont...
26

27
26. a. The projections on T13 significantly larger than those on T9, 32-42 antennal segments, 10-13 ocelli - this species will only key out here if the colour is more uniform than usual.
b. Projections on T9, 11, 13 all very pronounced, 39-45 antennal segments, 7-9 ocelli.
Lithobius melanops

Lithobius macilentus
End

End
27. a. 28-34 antennal segments, accesory spine between VpP15 and DpP15 - this species will only key out here if the colour is more uniform than usual.
b. 36-45 antennal segments, no accesory spine between VpP15 and DpP15
Lithobius borealis.

Subgenus Lithobius (Lithobius) cont...
End

28
28. a. 14-18 ocelli in 4-5 rows, 36-43 antennal articles, T9 projections not noticably broader than the others, head not typically darker than the body.
b. 10-12 ocelli, 40-45 antennal articles, T9 projections broader than the others, head typically darker than the body.
Lithobius tenebrosus

Lithobius tricuspis
End

End
KEY TO THE ORDER GEOPHILOMORPHA
29. a. Body greyish except orange at both ends.
b. Different body colour.
ORDER GEOPHILOMORPHA cont...
ORDER GEOPHILOMORPHA cont...
30
31
30. a. 51-57 leg pairs, often found on vertical surfaces eg walls, tree trunks.
b. >63-75 leg pairs, usually found on the ground.
Geophilus carpophagus
Henia vesuviana
End
End
31. a. Body distinctly reddish throughout (if uncertain key both ways).
b. Body not distinctly reddish throughout.
ORDER GEOPHILOMORPHA cont...
ORDER GEOPHILOMORPHA cont...
32
36
32. a. 37-41 leg pairs, body distinctly tapering toward the head.
b. At least 45 leg pairs, body tapering or not.
Strigamia acuminata
ORDER GEOPHILOMORPHA cont...
End
33
33. a. Body distinctly tapering toward the head, 47-53 leg pairs.
b. Body not tapering toward the head, 45-53 leg pairs.
Genus Strigamia
ORDER GEOPHILOMORPHA cont...
34
35
34. a. Pleurites of the final trunk segment fused to the pretergite, 49-53 leg pairs, widespread.
b. Pleurites of the final trunk segment not fused to the pretergite, 47-51 leg pairs, exclusively littoral including in estuaries.
Strigamia crassipes
Strigamia maritima.
34
35
35. a. Hind legs with claw, in males hind legs only moderately swollen, widespread
b. Hind legs without claw, in males hind legs grossly swollen, exclusively littoral SW.
Geophilus easoni
Hydroschendyla submarina
End
End
36. a. Antennae with elongate articles so that the length of the antennae are five or more times as long as the width of the head, pale yellowish species with distinctly redder heads.
b. Antennae and their constituent articles shorter relative to the head, colour contrast between the body and head less distinct if present.
Genus Geophilus

ORDER GEOPHILOMORPHA cont...
37

39
37. a. 49 leg pairs.
b. 51-57 leg pairs.
c. 59-63 leg pairs.
Geophilus flavus
Genus Geophilus cont...
Geophilus osquidatum
End
38
End
38. a. Exclusively found in littoral habitats, carpophagus fossae on underside, may have 51 leg pairs.
b. May be found anywhere, no carpophagus fossae on underside, may have 51 leg pairs.
c. Known distribution Wales, Western and Southern England, carpophagus fossae on underside, at least 53 leg pairs.
Geophilus seurati
Geophilus flavus
Geophilus osquidatum
End
End
End
39. a. >90 leg pairs (Cornwall).
b. 77-83 leg pairs.
c. 59-75 leg pairs.
d. 51-57 leg pairs.
e. <51 leg pairs.
Haplophilus souletina
ORDER GEOPHILOMORPHA cont...
ORDER GEOPHILOMORPHA cont...
ORDER GEOPHILOMORPHA cont...
ORDER GEOPHILOMORPHA cont...
End
40
41
42
44
40. a. Hind coxae dorsally covered in pores, head shorter than broad, max 83 leg pairs.
b. Hind coxae not dorsally covered in pores, head as long as broad, max 81 leg pairs.
Haplophilus subterraneus
Stenotaenia linearis
End
End
41. a. Forcipular tergite trapezoidal, (narrower anteriorly) and straight sided, some coxal pores opening dorsally at the base of the hind coxae, head slightly longer than broad
b. Forcipular tergite not much narrower at the front and with rounded edges, hind coxae without dorsal pores, head as long as broad).
Geophilus electricus

Stenotaenia linearis
End

End
42. a. Short for its leg count (<20mm) and very pale with hind legs stubby.
b. longer species, yellower with darkened head, hind legs normal.
Henia brevis
Genus Geophilus
End
43
43. a. Not in Shetland, (with an isolated ventral pore in the centre of the hind coxae, forcipule without an accessory claw).
b. Shetland, (but is *G impressus* present there too? Currently no records) (without an isolated ventral pore in the centre of the hind coxae, forcipule with an accessory claw).
Geophilus impressus
Geophilus proximus
End
End
44. a. Hind coxae dorsally covered in pores, head distinctly (>1.25x) longer than broad.
b. Hind coxae not dorsally covered in pores, head barely longer than broad.
ORDER GEOPHILOMORPHA cont...
ORDER GEOPHILOMORPHA cont...
45
48
45. a. Head in dorsal view parallel sided, forcipular tergite also parallel sided, coastal sites, head not distinctly narrower than gap between the poison claws, found outside in the UK.
b. Head distinctly narrower than the gap between the poison claws, broadest at the front; forcipular tergite very narrow, trapezoid, giving the appearance of a neck between the claws, only known from greenhouses.
Pachymerium ferrugineum

Family Mecistocephalidae
End

46
46. a. 49 leg pairs, head twice as long as broad, up to about 40mm only known from the Eden project.
b. <49 leg pairs, head about 1.3x as long as broad, body may be distinctly longer or distinctly shorter
Mecistocephalus guildingi
Family Mecistocephalidae cont...
End
47
47. a. 45 leg pairs, short species up to 20mm, known from various greenhouses in southern England.
b. 43 leg pairs, long species up to 60mm, old records from greenhouses in Northern England and Scotland.
Tygarrup javanicus
Dicellophilus carniolensis
End
End
48. a. 35-37 leg pairs, stocky orange yellow species, forcipular tergite very short.
b. At least 37 leg pairs, normally proportioned and paler species, sometimes with head slightly redder, forcipular tergite normal.
Eurygeophilus pinguis
ORDER GEOPHILOMORPHA cont...
End
49
49. a. Exactly 45 leg pairs, pallid species, very slender hind legs ending in a bristled tubercle. Scilly, Cornwall coasts.
b. Hind legs different.
Arenophilus peregrinus
ORDER GEOPHILOMORPHA cont...
End
50
50. a. 37-39 segments, pale species, head resembling Pachymerium, hind leg normal (metatarsus not reduced) with claw, Scilly and Isle of Wight.
b. If 39 segments then either hind leg with reduced metatarsus or typical Geophilus appearance (yellowish with darker head).
Nothogeophilus turki

ORDER GEOPHILOMORPHA cont...
End

51
51. a. Hind legs with the final segment much shorter and without claw, pale species.
b. Hind legs normal with claw.
Genus Schendyla
Genus Geophilus
52
54
52. a. Hind legs relatively long (>1.5x the previous pair ignoring coxae), the final segment of the hind legs 1/3-1/2 as long as the penultimate, not shorter, 37-43 leg pairs.
b. Hind legs <1.5x as long as the previous pair ignoring coxae, the final segment <1/3 as long as the penultimate, 39-49 leg pairs.
Schendyla nemorum

Genus Schendyla cont...
End

53
53. a. The final segment of the last leg 1/5-1/3 the length of the penultimate, 39-49 leg pairs, exclusively coastal and southern.
b. The final segment of the last leg minute - <1/7 the length of the penultimate, 39 leg pairs exactly, widespread.
Schendyla Peyerimhoffi
Schendyla dentata
End
End
54. a. At least 45 leg pairs.
b. Fewer than 45 leg pairs.
Genus Geophilus cont...
Genus Geophilus cont...
43
55
55. a. Head 1.3x as long as broad and rather rectangular, coastal sites, southern, males 41 leg pairs, females 43 leg pairs.
b. Head about as long as broad, widespread, males 37-39 leg pairs, females 39-41
Geophilus pusillifrater
Geophilus truncorum
End
End

British Geophilomorpha by Number of Leg Pairs

Colours represent families: Green = Geophilidae, Red = Lintotaeniidae, Pale yellow = Schendylidae, Purple = Mecistocephalidae, Grey = Dignathodontidae, Golden brown = Himantariidae,

British Lithobiomorpha by Number of Antennal Articles:

Colours in header row represent subgenera: Cyan = Lithobius (Monotarsobius), Purple = Lithobius (Sigibius) [Myriatrix] or Lithobius (Polybothrus) [Chilobase], Yellow = Lamyctes (Lamyctes), Green = Lamyctes (Metalamyctes), Red = Lithobius (Lithobius)

Colours in the body represent tergite projections: Red (Lithobius) and Black (Lamyctes) = No tergite projections, Yellow = T7, 9, 11 and 13, Green = T9, 11 and 13, Blue = T11 and 13 but pale blue are those variable or ambiguous species that usually have T11 and 13 only but may also have T9 (borealis) or may lack projections of T11 and even occasionally T13 (lapidicola)


Posted on March 27, 2023 03:30 PM by matthewvosper matthewvosper

Comments

@bmig_steve @szucsich and here are the centipedes...

Posted by matthewvosper 11 months ago

Great stuff @matthewvosper :-)This looks really useful.

Posted by bmig_steve 8 months ago

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