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Status and distribution European and world distribution Coenagrion mercuriale (Charpentier) Southern damselfly Description The males of this small and dainty damselfly are predominantly blue and black, in common with other species in this genus. Typically they possess a 'mercury' sign On segment 2 of the abdomen, but this mark is subject to some variation and may superficially resemble C. pulchellum and C. scitulum. The pattern of black markings on the dorsal surface of the abdomen is usually quite distinctive, however. The shape of the anal appendages is diagnostic. Females are dark with pale olive-green or blue sides to the thorax and abdomen, extending to the dorsal abdominal surface as thin inter-segmental rings. Females of C. mercuriale can be distinguished from C. puella and Enallagma cyathigerum, with which they may be found, by the markings on the sides of the thorax and on the head (Welstead & Welstead 1983b), and from female C. pulchellum by the almost straight hind margin of the pronotum. Habitat C. mercunale breeds in base-rich runnels and streams, often in heathland areas but it is not confined to these (Merritt 1983a). Mayo and Welstead (1983) discuSs its occurrence on water-meadow ditches on the floodplains of two chalk rivers. Colley (1983) describes its presence on a spring flush in a calcareous valley mire on Anglesey. Winsland (1985) discusses its habitat requirements on the New Forest heathlands. Water at breeding sites is usually shallow and slow-flowing over a gravel or marl bed overlaid in places with organic detritus. Breeding biology The males are not territorial. Populations are usually small but densities of 250 per 100 m of stream can occur. Jenkins (1991) reviews a population study at a site in the New Forest. Oviposition occurs in tandem. The eggs are inserted into the tissues of aquatic and emergent plants such as marsh St John's-wort, black bog-rush, bog pondweed, and fool's water-cress. Larvae usually take two years to develop. Details of larval development are given by Corbet (1957). Flight periods C. mercunale has a relatively short flying season from early June to mid-August. It has a slow, weak flight, low down amongst emergent vegetation. In heathland localities, it may be seen with or near colonies of Ceriagnon tenellum, Ischnura pumilio, and Orthetrum coerulescens. On water meadows it may be found settled amongst lush vegetation with Calopteryx splendens, Coenagrion puella and I. elegans. C. mercuriale is confined to a few southern and western counties in England and Wales. It has not been recorded from Ireland. Its strongholds are the New Forest heathlands and Mynydd Preseli in Pembrokeshire. Elsewhere it breeds at a few sites on the Dorset heaths, east Devon pebble-bed commons, Gower peninsula, Anglesey, and the floodplains of the River Itchen and River Test in Hampshire. In July 1991, a single adult male was captured at Cothill Fen, Oxfordshire (too late to be included in the maps). C. mercunale is subject to many threats, principally the cessation of grazing by stock animals (Evans 1989) resulting in the smaller runnels and streams becoming completely overgrown with rank vegetation such as purple moor-grass. Other threats include excessiVe nutrient enrichment from the runoff of nitrogenous fertilizers from adjacent agricultural land, drainage due to agricultural and forestry pressures and, in the case of water meadows, over-extraction of water by water companies resulting in lowering of the water table. C. mercuriale has become extinct in Cornwall, having last been seen at its site at Trevorgans near St Buryan in 1957, and has been lost from several of its former sites in Devon during the 1950s and 1960s. It has also declined in Dorset. The species does not wander far from its breeding sites, and this apparent lack of dispersal ability could hinder its spread to suitable habitat in neighbouring areas. It needs rigorous protection. C. mercuriale has a restricted range on the continent, centred on south-west Europe and North Africa, becoming rare further north and east. It is threatened throughout most of its range, and is the only British resident dragonfly species to 42
Coenagrion mercuriale (Charpentier) Southern damselfly 1975-90 o 1950-74 O Pre-1950 43 0 0 OS be listed in the European Communities 'Habitats and Species' Directive, and in the Appendices to the Berne Convention. It occurs on several National Nature Reserves (NNRs) and one Royal Society for the Protection of Birds (RSPB) reserve.
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Cover photograph: Aeshna juncea Ins
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@ NERC Copyright 1996 ISBN 0 11 701
Page 7 and 8: FOREWORD Having been on the fringe
Page 9 and 10: ACKNOWLEDGMENTS The following list
Page 11 and 12: Howard, G.; Howard, LW; Howe, M.; H
Page 13: Walker, D.S.; Walker, FA; WaLker, I
Page 16 and 17: CHECKLIST The following checklist i
Page 18 and 19: Aeshna mixta Latreille 1805 Aeschna
Page 20 and 21: THE BRITISH AND IRISH ODONATA IN A
Page 22 and 23: of distributions of dragonflies usi
Page 24 and 25: I 00 o o Figure 3. Map of coverage
Page 26 and 27: ,o " Figure 5. Map of coverage at t
Page 28 and 29: FIELDWORK AND DATA MANAGEMENT METHO
Page 30 and 31: areas, and encouraged in this by bo
Page 32 and 33: Table 3. Distribution of each speci
Page 34 and 35: Table 4 (con°. Vice-county distrib
Page 36 and 37: Table 4 (cont). Vice-county distrib
Page 38 and 39: Computerisation and validation Havi
Page 40 and 41: dominance of one individual over an
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: Erythromma najas (Hansemann) 1975-9
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
Page 75 and 76: Ischnura elegans (Vander Linden) 19
Page 77 and 78: Ceriagrion tenellurn (Villers) 1975
Page 79 and 80: Aeshna caerulea (Strom) Azure hawke
Page 81 and 82: Aeshna juncea (Linnaeus) Common haw
Page 83 and 84: Montiaghs Moss, near Aghalee, Co An
Page 85 and 86: Sundon Springs chalk quarry, near L
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
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Cordulia aenea (Lin.naens) Downy em
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Somatochlora metallica (Vander Lind
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Somatochlora arctica (Zetterstedt)
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Oxygastra curtisii (Dale) Orange-sp
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Libellula quadrimaculata Linnaeus 1
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Libellula fulva Mailer Scarce chase
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Libellula depressa Linnaeus 1975-90
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Orthetrum cancellatum (Linnaeus) 19
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Orthetrum coerulescens (Fabricius)
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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,
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