British Insects: the Odonata (Dragonflies and Damselflies)
| British Insects: the Odonata (Dragonflies and Damselflies) | |
#1. <Synonyms:>/
#2. <Common names:>/
mm long/
The ranges given here are mostly taken from Lucas (1900), with the interpolation of mean values quoted from Hammond (1983).
When constructing keys for practical application, the existence of intraspecific variation is no excuse for downweighting differences of obvious identificatory value in favour of obscure morphological features, regardless of the supposed taxonomic “importance” of the latter. See further comment under ‘wingspan’.
#4. Average wingspan <mid-thorax to wing-tip, X 2; records with an inbuilt allowance of +/- 20%, permitting measurements on single specimens to be used for interactive identification>/
mm/
Measured with the front edges of the hindwings at right angles to the body. The figures given are quoted from Hammond (1983).
This character exemplifies very well the value of simple estimates of size as primary identificatory separators, although they are invariably ignored in favour of obscure morphological features in printed keys. In the present case, the data on wingspan remain a very useful primary separator in INTKEY, even automatically allowing (as here) for variation of 20% above and below the means given by Hammond. See “Percent error”, in Dallwitz, M. J., Paine, T. A., and Zurcher, E. J. (1995 onwards): User’s guide to Intkey.
#5. Hindwings <length>/
mm long/
Measurements are quoted from Hammond (1983), cross referenced with Lucas (1900).
When constructing keys for practical application, the existence of intraspecific variation is no excuse for downweighting differences of obvious identificatory value in favour of obscure morphological features, regardless of the supposed taxonomic “importance” of the latter. See further comment under ‘wingspan’.
#6. The <compound> eyes <of adults, insertion and distance apart>/
1. lateral and widely separated <separated by more than their dorsal diameter>/
2. dorsally narrowly apposed <very close or meeting only at a point>/
3. dorsally broadly contiguous/
#7. The <compound> eyes <of adults, colour>/
1. grey/
2. black/
3. brown/
4. red/
5. green/
6. blue/
#8. The front of the head immediately interior to the eyes <colour>/
1. pale whitish blue/
2. not pale whitish blue <implicit>/
#9. The three ocelli <of adults, arrangement>/
1. arranged in a triangle <implicit>/
2. in a row/
#10. The narrow black band at the base of the frons <configuration>/
1. conspicuously continued for some distance down the inner sides of the eyes/
2. only briefly continued down the inner sides of the eyes/
3. not continued down the inner sides of the eyes/
#11. Thorax <whether very hairy>/
1. very hairy/
2. not very hairy <implicit>/
#12. The prothorax <shape>/
1. <of both sexes> deeply two-cleft posteriorly, resulting in a distinctly 3-lobed posterior margin/
2. <of both sexes> posteriorly more or less entire <no more than indistinctly 3-lobed>/
#13. Legs <colour>/
1. black/
2. black and yellow/
3. black and brown/
4. black and blue/
5. pale red/
#14. Legs <whether red>/
1. pale red/
2. not red <implicit>/
#15. Hind tibia <of adults, whether with a feather-like extension>/
1. with a conspicuous featherlike expansion/
2. without a featherlike expansion <implicit>/
#16. Thoracic antehumeral stripes <of adults, presence>/
1. present/
2. absent/
#17. Thoracic antehumeral stripes <colour>/
1. greyish/
2. blue/
3. violet/
4. green <or greenish>/
5. yellow <or yellowish>/
6. orange/
7. red/
8. brown/
#18. The <forewings and hind-> wings <posture in repose>/
1. held vertically in repose/
2. spread more or less horizontally in repose/
3. held partly open in repose/
#19. The <forewings and hind-> wings <similar or different>/
1. similar in shape and venation/
2. dissimilar in shape and venation <the hindwings broadened basally>/
#20. The <forewings and hind-> wings <petiolate or sessile>/
1. petiolate <basally narrowed>/
2. sessile/
#21. The <forewings and hind-> wings <patterning and colouring>/
1. unpatterned and clear <except for venation and pterostigma>/
2. suffused with colour at their bases only/
3. suffused with colour basally and in the leading half/
4. suffused with colour basally and (in the forewings only) in a patch near the cubital point/
5. colour tinted throughout/
6. with a sharply defined, dark brown basal fascia/
7. with a broad, purple-brown to deep blue-violet fascia extending from costa to hind margin, and occupying all but their bases and tips/
8. with a large purplish brown to deep Prussian blue fascia, extending from costa to hind margin, and nearer to the apex than the base/
#22. The tinting <of tinted as opposed to fasciated wings, colour>/
1. amber/
2. light brown/
3. dull greenish brown/
4. dull purplish brown/
#23. The inner wing venation <excluding the costa: colouring>/
1. red/
2. brown/
3. blackish/
#24. Discoidal cell <of forewings and hindwings, whether divided into triangle and supra-triangle>/
1. a simple <trapezoid or elongated-rectangular> quadrilateral, not longitudinally divided/
2. divided longitudinally into a conspicuous triangle and supra-triangle <sometimes with a subtriangle proximal to the former>/
#25. The <forewings and hind-> wings exhibiting <number of postquadrilateral cells between the quadrilateral (discoidal) cell and the subnodus>/
psqs cells between the quadrilateral <discoidal> cell and the subnodus/
#26. Antenodal veins in the forewings <number>/
#27. Antenodal veins in the forewings <whether including two obvious primaries>/
1. incorporating two conspicuously stronger primaries, and those in the costal and subcostal spaces unaligned/
2. without distinct primaries, and those in the costal and subcostal spaces more or less aligned/
#28. Pterostigma <presence>/
1. present <implicit>/
2. absent/
#29. Pterostigma <shape>/
1. more or less isodiametric/
2. elongated but only about about twice as long as wide/
3. well over twice but no more than five times as long as wide/
4. narrow-linear <well over five times as long as wide>/
#30. Pterostigma <colour>/
1. black/
2. dark brown/
3. reddish brown/
4. light brown/
5. yellow/
6. orange/
7. red/
8. white/
9. pale with a dark centre/
#31. The hindwings <number of cell rows distal to the pterostigma>/
1. with only one row of cells distal to the pterostigma between the costa and the radial vein/
2. with two rows of cells distal to the pterostigma between the costa and the radial vein/
#32. Abdomen <of adults, shape in dorsal view>/
1. lanceolate <relatively broad, dorsiventrally flattened>/
2. <more or less> linear from base to tip/
3. <more or less> linear from a conspicuously swollen base <the swelling generally involving segments 1–3; sometimes briefly constricted immediately behind the basal swelling>/
4. swollen both basally and distally and markedly constricted in between/
#33. Abdomen <length, including anal appendages>/
mm long/
Measurements are quoted from Hammond (1983), cross referenced with Lucas (1900).
When constructing keys for practical application, the existence of intraspecific variation is no excuse for downweighting differences of obvious identificatory value in favour of obscure morphological features, regardless of the supposed taxonomic “importance” of the latter. See further comment under ‘wingspan’.
#34. Abdomen predominantly <ground colour>/
1. grey/
2. blue/
3. green/
4. bronze/
5. red/
6. yellow/
7. brown/
8. black/
#35. Abdomen <whether metallic>/
1. metallic/
2. non-metallic/
#36. Abdomen <of adults, patterning>/
1. plain/
2. predominantly transversely banded/
3. predominantly longitudinally lined/
4. complexly patterned <with bands and/or lines and/or spots>/
#37. Abdomen <of adults, presence of yellow triangle on segment 2>/
1. with a conspicuous, median yellow triangle on segment 2/
2. without a yellow triangle on segment 2 <implicit>/
#38. Abdomen <of adults, mid-dorsal spots>/
1. with mid-dorsal spots/
2. without mid-dorsal spots/
#39. Abdominal segments 9 and 10 <of adults, markings: for Aeshna species>/
1. exhibiting complete <blue or green> bands/
2. unbanded, but each with a pair of <blue or green> rounded posterior spots/
3. unbanded, but each with a pair of more or less rectangular <blue or green> spots/
4. neither colour-banded nor colour-spotted/
#40. Abdominal segment 2 of the male <markings>/
1. blue, with a black U-shaped dorsal mark which is separated from the black circlet behind it <no lateral black lines>/
2. blue, with a black U-shaped dorsal mark which is joined to the black circlet behind it <no lateral black lines>/
3. blue, with a complex dorsal black Mercury mark <a circle with two horns in front, and a strong stem behind joining it to a posterior circlet; no lateral black lines>/
4. blue, with a more or less spear-shaped but variable dorsal black mark joined to the black posterior circlet, and consistently exhibiting a black line on either side/
5. blue, with only a broad black band near the middle/
#41. The male abdomen <auricles>/
1. auriculate on segment 2/
2. without auricles on segment 2/
#42. The male abdomen <inferior anal appendages, paired or single>/
1. with paired inferior anal appendages <and two superior ones>/
2. with a single inferior anal appendage <and two superior ones>/
#43. Abdominal segment 8 of the female <presence of ventral spine>/
1. with a ventral apical spine/
2. without a ventral apical spine/
#44. The <adult> female <presence of conspicuously long ovipositor>/
1. with a relatively very long ovipositor/
2. without a long ovipositor <implicit>/
1. elongate and slender-bodied, gradually tapering posteriorly/
2. <relatively> stout, the body expanded in the middle/
Identifications of nymphs cannot be pursued with optimism until they are sufficiently mature; i.e., until the wing sheaths reach beyond the third abdominal segment.
#46. The nymphs when mature, <length, including posterior appendages>/
mm long/
#47. The head <of nymphs, spotting>/
1. with prominent spots/
2. without prominent spots/
#48. The eyes <of nymphs, size>/
1. small <less than half the length of the posterior margin of the postocular lobe>/
2. large <at least half as long as the posterior margin of the postocular lobe>/
#49. The eyes <of nymphs, insertion on the head>/
1. lateral and widely separated on the top of the head <separated by more than their dorsal diameter>/
2. approaching one another closely at a point on the top of the head/
#50. The eyes <of nymphs, dorsal flattening>/
1. markedly flattened dorsally, their posteror margins forming a transverse straight line in dorsal view/
2. convex dorsally, their posterior margins not aligned/
#51. The head <of nymphs> in dorsal view <shape>/
1. markedly narrowing <the postocular lobes sloping inwards> from immediately behind the eyes/
2. not markedly narrowing from immediately behind the eyes/
#52. The postocular lobes <of nymphs, shape>/
1. curving smoothly to the back of the head from immediately behind the eyes/
2. curving sharply to the back of the head from some distance behind the eyes <with a more or less marked latero-posterior bulge>/
#53. The antennae <of nymphs, numbers of segments>/
segmented/
#54. The antennae <of nymphs, elongation of the scape (first segment)>/
1. with the scape <first segment> as long as the other segments taken together/
2. with the scape considerably shorter than the other segments taken together/
#55. The antennae <of nymphs, relative length of first flagellar segment>/
1. with the first flagellar segment <segment3> shorter than the pedicel <segment 2>/
2. with the first flagellar segment longer than the pedicel/
#56. The mask <of nymphs, shape>/
1. abruptly narrowed well before the hinge, with the prementum stalked <“ladle-shaped”>/
2. narrowed gradually to the hinge <often more or less triangular>/
#57. The prementum <of nymphs, length relative to front width>/
1. quite elongated, being nearly twice as long as the width of its front/
2. relatively short, being much less than twice as long as its front width/
#58. The mask <of nymphs, spoon-shaped or flat>/
1. having the prementum hollowed dorsally <“spoon-shaped”, covering the face>/
2. with a flat prementum/
#59. The mask <of nymphs, cleft of prementum>/
1. with a wide median cleft extending half the length of the prementum/
2. with a short slit-like median cleft/
3. with the median lobe of the prementum shortly apiculate and bifid/
4. without a median cleft <and prementum not apiculate-bifid>/
#60. The cleft <in the prementum of the nymphs, width>/
1. less than four times as long as its maximum width/
2. more than four time as long as its maximum width/
#61. The prementum <of the mask of nymphs> bearing <number of setae>/
major setae/
#62. The body of the labial palps bearing <of nymphs, number of major setae>/
major setae/
#63. The outer margins of the labial palps <of nymphs, whether armed with small spines>/
1. armed with small spines/
2. without spines/
#64. Distal margins of the labial palps <of nymphs, incision>/
1. <more or less> entire <smooth>/
2. crenate/
3. finely toothed/
4. coarsely toothed/
#65. The moveable hooks of the labial palps <of nymphs, number of setae>/
1. without setae <dubiously implicit>/
2. with two setae/
3. with three or more setae/
#66. Legs <of the nymph, relative length>/
1. shorter than the abdomen/
2. longer than the abdomen/
#67. The apical combs of the tibiae <of nymphs, form of setae>/
1. mainly of bifurcated setae/
2. mainly of trifurcated setae/
3. of “spinate” <unbranched?> setae/
#68. Fore- and middle tarsi <of the nymph, number of segments>/
1. 2-segmented/
2. 3-segmented/
#69. The abdomen <of nymphs, presence of three caudal gills or five spine-like appendages>/
1. terminating in three conspicuous caudal <lamellate> gills/
2. terminating in five short spine-like appendages <when not spread, constituting the armed ‘anal pyramid’ protecting the rectal gills and anus; comprising a median dorsal ‘appendix dorsalis’, paired ventro-lateral paraprocts or cerci, and paired dorso-lateral paraprocts or ‘cercoids’>/
#70. The three caudal appendages <of zygopteran nymphs, whether all lamellar>/
1. all lamellar/
2. comprising a lamellar median and three-edged laterals/
#71. The caudal lamellae <of nymphs, shape in outline>/
1. oval <broadest in the middle, symmetrically curved>/
2. lanceolate <or ovate: broader and more strongly curved below the middle>/
3. oblanceolate <or obovate: broader and more strongly curved beyond the middle>/
#72. The caudal lamellae <of nymphs, shape of tip>/
1. blunt/
2. pointed/
#73. The caudal lamellae <of nymphs, colouring>/
1. hyaline without coloured markings/
2. with transverse dark bands/
3. patterned beyond the middle with conspicuous a dark cross/
4. mottled with brown/
5. spotted/
#74. The caudal lamellae <of nymphs, occurrence of marginal setae>/
1. hairy on both margins to beyond the middle/
2. with one margin hairless beyond the middle, the other hairy to nearer the apex/
#75. The caudal lamellae <of nymphs, whether exhibiting nodes>/
1. nodate, with the marginal hairs coarser proximally to the node and finer beyond it/
2. without nodes, and with no clear demarcation between proximal and distal series of marginal hairs/
#76. The caudal lamellae <of nymphs, tracheal branching pattern>/
1. with the primary tracheal branches departing more or less at right angles to the main trunk, themselves branching only near the margin/
2. with much-branched primary tracheal branches leaving the main trunk at an upward angle/
#77. The cerci <of nymphs, relative length>/
1. more than half the length of the paraprocts/
2. no more than hald the length of the paraprocts/
#78. The abdomen <of nymphs, whether with mid-dorsal spines>/
1. with mid-dorsal spines/
2. without mid-dorsal spines <dubiously implicit>/
#79. The mid-dorsal abdominal spines <of nymphs, distribution>/
1. prominent on segments 3 to 8/
2. prominent on segments 3 to 6/
3. prominent on segments 4 to 8/
4. prominent on segments 4 to 7/
5. prominent on segments 4 to 9/
6. prominent on segments 4 to 6/
7. prominent on segments 5 to 8/
8. prominent on segments 5 to 7 only, but sometimes a vestigial one on segment 8/
9. prominent on segments 6 to 8 only/
#80. The abdomen <of nymphs, mid-dorsal spine on segment 8>/
1. with a prominent mid-dorsal spine on segment 8/
2. without a mid-dorsal spine on segment 8/
#81. The ventral surface of the abdomen <of nymphs, banding>/
1. with distictive dark longitudinal bands/
2. without distictive markings/
#82. The gizzard <of nymphs, number of folds>/
1. with 4–8 folds/
2. with 8–16 radially symmetrical folds/
1. northern Scotland/
2. southern Scotland/
3. northern England/
4. English Midlands/
5. East Anglia/
6. Wales/
7. southeast England/
8. central southern England/
9. southwest England/
10. Isle of Wight/
11. Ireland/
Known distributions of organisms are obviously taxonomically useful, but equally obviously, they have to be used with caution. The very detailed data provided by Hammond and Merritt (1985) have therefore been geographically generalized here, mainly to render them practicable and reasonably reliable for helping with identifications. The distributions have automatically been widened, by recording them quite liberally under the broad regions used here; and the routine advice we advocate when using INTKEY (if in doubt, select more than one character state) remains available to users as a further precaution.
Southern Scotland: south of the Firth of Forth.
Northern England: including north Derbyshire, Cheshire, Lancashire, Yorkshire, north Lincolnshire.
English Midlands: central England, including Warwickshire, Northamptonshire, Leicestershire, Nottinghamshire, southern Lincolnshire, Derbyshire, Staffordshire, Worcestershire, Shropshire, Herefordshire, etc.
East Anglia: eastern England south of The Wash, including Norfolk, parts of Cambridgeshire and Essex.
Southeast England: including London and the Home Counties, Kent, East Sussex.
Central southern England: including Oxfordshire, Gloucestershire, Buckinghamshire, Hampshire, east Dorsetshire, Wiltshire.
Southwest England: west Dorset, Somerset, Devonshire, Cornwall.
#84. Adults on the wing <months>/
1. late April/
2. early May/
3. late may/
4. early June/
5. late June/
6. early July/
7. late July/
8. early August/
9. late August/
10. early September/
11. late September/
12. early October/
13. late October/
14. early November/
Adults found earlier or later during the flight periods given are likely to exhibit immature or very mature (i.e., atypical) colouration.
1. Zygoptera/
2. Anisoptera/
#86. Family/
1. Platycnemididae/
2. Coenagriidae <Agrionidae>/
3. Lestidae/
4. Agriidae <Calopterigidae>/
5. Gomphidae/
6. Cordulegasteridae/
7. Aeshnidae <Aeschnidae>/
8. Corduliidae/
9. Libellulidae/
#88. Abbreviated taxon name:/
#89. <Illustrations>/
#90. <Whether specimen male or female:>/
1. <mature adult> male/
2. <mature adult> female/
To view the illustrations with detailed captions, go to the interactive key. This also offers full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting or lacking specified attributes, and distributions of character states within any set of taxa.
Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 2003 onwards. British insects: the Odonata (dragonflies and damselflies). Version: 9th April 2007. http://delta-intkey.com’.