Description C. tenellum is one of two British damselflies in which the male is predominantly red, but is smaller and daintier than the much more common Pyrrhosoma nymphula. The abdomen of the male, and one of the three female forms (var. erythrogastrum Sélys-Longchamps), is entirely crimson-red, unlike P. nymphula. Other distinguishing features are the red legs, red pterostigmata and the lack of antehumeral stripes on the bronze-black dorsal surface of the thorax. In one of the other two female colour forms (var. intermedia Sélys-Longchamps), the anterior three abdominal segments are mostly red dorsally, the remaining segments being black. In the third female colour form (var. melanogastrum Sélys-Longchamps) the abdomen is entirely black apart from thin yellow intersegmental abdominal rings, but the dull reddish legs and red pterostigmata distinguish it from other species. Breeding biology C. tenellum is territorial, but can occur at very high densities — approaching 150 per 100 m of water's edge. Copulation can take as long as 90 minutes. The female oviposits in tandem, inserting her eggs into the tissues of Sphagnum moss and other aquatic and emergent plants. The larvae live among the peaty detritus and plant roots, and usually take two years to develop. . Flight periods C. tenellum is on the wing from early June to early September. In heathland areas it can be found by slow-flowing runnels with Coenagrion mercuriale and Ischnura pumilio, and on bog pools in valley mires with Orthetrum coerulescens. When Sphagnum bogs are marginal to larger heathland ponds, C. tenellum may occur with a much wider range of species, including Aeshna juncea, Anax imperator, Sympetrum danae and Lestes sponsa. Status and distribution The distribution of C. tenellum is strongly influenced by its habitat requirements. European and world distribution Ceriagrion tenellum (Villers) Small red damselfly Habitat C. tenellum typically breeds in shallow bog pools, fringed with Sphagnum moss, on lowland heaths. These pools often contain lesser bladderwort, marsh St John'swort and marginal grasses, sedges and bog-myrtle through which the adults fly weakly, seldom wandering far. C. tenellum is also found in peaty ditches on a few cut-over bogs and poor fens, as well as the shallow well-vegetated margins of old ball-clay and china-clay ponds, and old marl pits. It is not restricted to static water, and can occur on slow-flowing water on heathlands, and on former tinstreaming sites in Cornwall. It is also found on a few calcareous valley mires where it occupies shallow, often tiny, peaty pools within areas dominated by plants such as blunt-flowered rush, black bog-rush, and often with a loose scattering of common reed. However, a climatic factor is probably involved as well, limiting its range to the southern half of Britain. It has not been reliably recorded from Ireland, though apparently suitable habitat is present in some central and southern counties. In Britain, it is most commonly found in the heathland areas of the Surrey/Hampshire border, the New Forest, Dorset, Cornwall and Pembrokeshire. It occurs on several calcareous valley mires in Anglesey, the Lleyn peninsula, and at Cothill Fen in Oxfordshire and one locality in Norfolk. Its last Suffolk records were from Redgrave Fen in the 1940s and from heathland at Fritton Warren in the 1950s. It became extinct at Wicken Fen, Chippenham Fen and Gamlingay Bog in Cambridgeshire in the latter part of the 19th century Its Norfolk site is currently threatened by excessive extraction of water from underground aquifers, and by plans to widen an adjacent road. C. tenellum is vulnerable to seral changes in habitat. It bred regularly at a few sites on the Somerset Moors until the early 1970s, but became extinct as a result of the drying out of its habitat due to the lowering of the water table caused by adjacent peat extraction operations. C. tenellum is essentially a species of south-west Europe and the Mediterranean area, with isolated pockets further north as far as Britain and Germany, where it is probably at the limits of its ecological tolerance (Parr & Parr 1979). It also occurs in northern Morocco and Algeria. 62
Ceriagrion tenellurn (Villers) 1975-90 o 1950-74 o Pre-1950 a Se 00 63 SO 0.0 0 S 0 0 0 O Os 000 Small red damselfly o 0
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Cover photograph: Aeshna juncea Ins
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@ NERC Copyright 1996 ISBN 0 11 701
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FOREWORD Having been on the fringe
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ACKNOWLEDGMENTS The following list
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Howard, G.; Howard, LW; Howe, M.; H
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Walker, D.S.; Walker, FA; WaLker, I
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CHECKLIST The following checklist i
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Aeshna mixta Latreille 1805 Aeschna
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THE BRITISH AND IRISH ODONATA IN A
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of distributions of dragonflies usi
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I 00 o o Figure 3. Map of coverage
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- Page 28 and 29: FIELDWORK AND DATA MANAGEMENT METHO
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- Page 32 and 33: Table 3. Distribution of each speci
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- Page 38 and 39: Computerisation and validation Havi
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- Page 42 and 43: RESIDENT SPECIES Description Habita
- Page 44 and 45: Calopteryx splendens (Harris) Bande
- Page 46 and 47: Description Flight periods Status a
- Page 48: Description Lestes dryas Kirby Scar
- Page 51 and 52: Platycnemis pennipes (Pallas) White
- Page 53 and 54: Pyrrhosoma nymphula (Sulzer) 1975-9
- Page 55 and 56: Erythromma najas (Hansemann) 1975-9
- Page 57 and 58: Coenagrion mercuriale (Charpentier)
- Page 59 and 60: Coenagrion scituluni (Rambur) Daint
- Page 61 and 62: Coenagrion hastulatuni (Charpentier
- Page 63 and 64: Coenagrion lunulatum (Charpentier)
- Page 65 and 66: Coenagrion armatum (Charpentier) No
- Page 67 and 68: Coenagrion puella (Linnaeus) Azuxe
- Page 69 and 70: Coenagrion pulchellum (Vander Linde
- Page 71 and 72: Enallagma cyathigerurn (Charpentier
- Page 73 and 74: Ischnura pumilio (Charpentier) Scar
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- Page 79 and 80: Aeshna caerulea (Strom) Azure hawke
- Page 81 and 82: Aeshna juncea (Linnaeus) Common haw
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- Page 87 and 88: PLATE 1 Calopteryxvirgo adult PLATE
- Page 89 and 90: PLATE 13 Libellula fulva adult PLAT
- Page 91 and 92: Aeshna mixta Latreile Migrant hawke
- Page 93 and 94: Aeshna cyanea (Muller) Southern haw
- Page 95 and 96: Aeshna grandis (Linnaeus) Brown haw
- Page 97 and 98: Aeshna isosceles (Muller) Norfolk h
- Page 99 and 100: Anax imperator Leach Emperor dragon
- Page 101 and 102: Brachytron pratense (Muller) Hairy
- Page 103 and 104: Gomphus vulgatissimus (Linnaeus) 19
- Page 105 and 106: Cordulegaster boltonii (Donovan) Go
- Page 107 and 108: Cordulia aenea (Lin.naens) Downy em
- Page 109 and 110: Somatochlora metallica (Vander Lind
- Page 111 and 112: Somatochlora arctica (Zetterstedt)
- Page 113 and 114: Oxygastra curtisii (Dale) Orange-sp
- Page 115 and 116: Libellula quadrimaculata Linnaeus 1
- Page 117 and 118: Libellula fulva Mailer Scarce chase
- Page 119 and 120: Libellula depressa Linnaeus 1975-90
- Page 121 and 122: Orthetrum cancellatum (Linnaeus) 19
- Page 123 and 124: Orthetrum coerulescens (Fabricius)
- Page 125 and 126: Sympetrum striolaturn (Charpentier)
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Sympetrum sanguineum (Muller) Ruddy
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Sympetruni danae (Sulzer) 1975-90 o
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Leuconhinia dubia (Vander Linden) W
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IMIVLIGRANTS AND ACCIDENTAL SPECIES
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POSSIBLE ADDITIONS TO THE BRITISH A
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SEASONAL OCCURRENCE PREVIOUS REPRES
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700 600 500 400 300. 200 100 0 90 8
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70 60 50 40 30 20 10 90 80 70 60 50
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Finally, differences in recorder be
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ODONATA LOCALITY 6411 V10E-COUNTY N
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Particularly in the case of residen
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conditions and which may be of grea
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1960s from its single locality alon
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pond. One of the authors did this o
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REFERENCES Aguilar, J. d', Dommange
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Gabb, R. & Kitching, D. 1992. The d
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Coenagrion rnercuriale (Charpentier
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Dee'. Transactions of the Natural H
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Circumboreal Occurring in a band en
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Marl A whitish clay soil with a hig
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Vulvar scale WATCH Weald Wheel posi
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Appendix 2. LIST OF PLANT NAMES Pla
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Libefiula depressa 5,6,14,17,18,19,