The Barkflies & Booklice (Psocoptera)
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THE BARKFLIES & BOOKLICE (PSOCOPTERA) OF CORNWALL & THE ISLES OF SCILLY by Keith N.A. Alexander Metylophorus nebulosus (Stephens) Stenopsocus stigmaticus (Imhoff & Labram) THE BARKFLIES & BOOKLICE (PSOCOPTERA) OF CORNWALL & THE ISLES OF SCILLY Keith N.A. Alexander CISFBR (Cornwall and Isles of Scilly Federation for Biological Recorders) & ERCCIS (Environmental Records Centre for Cornwall and the Isles of Scilly) OCCASIONAL PUBLICATIONS No. 3 2011 CISFBR & ERCCIS OCCASIONAL PUBLICATIONS No. 3 2011 Design and typesetting by Wheal Seton Press Dr. Colin French, 12 Seton Gardens, Weeth Road, Camborne, Cornwall TR14 77S, UK. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise without the permission of the copyright owners. Copyright © KNA Alexander & CISFBR ISBN: 1-902864-08-5 Contents 1 INTRODUCTION 1 2 SPECIAL FEATURES OF THE CORNISH FAUNA 1 3 SPECIES TOTALS 2 4 EQUIPMENT FOR FIELDWORK 2 5 RETENTION OF VOUCHER SPECIES 3 6 USEFUL LITERATURE 3 7 NATIONAL RECORDING SCHEMES 3 8 RECORDING IN CORNWALL 3 9 THE CATALOGUE OF BARKFLIES & BOOKLICE OF CORNWALL & THE ISLES OF SCILLY 4 9.1 Sources of Records 4 9.2 Area of Study 4 9.3 Nomenclature 4 9.4 Status 4 9.5 Organisation of 10km Square Records 7 9.6 Abbreviations used for recorders 7 9.7 Mapping 7 9.8 Details of species ecology and local records in current taxonomic order 8 Acknowledgements 18 References 18 Index 19 1 INTRODUCTION Nearly 100 species of Psocoptera have been recorded in Britain. Although amongst the least known of insects, they are actually abundant in the Cornish countryside, especially on trees and shrubs, and some live with us in our homes and work places. All are small, soft- bodied insects, often with distinctively patterned wings but some have reduced wings and are flightless. The species which naturalists are most likely to come across and identify are the free- living species known as barkflies and which occur on trees and shrubs – the arboreal group. Other wild situations which support a few species include: • leaf-litter beneath concentrations of trees and shrubs, • tall grassy vegetation, particularly reed beds and fens, but also dry calcareous or base- rich grasslands; • rock faces with lichen growth. The arboreal barkflies found in Britain fall into two well-defined ecological groups. Most species are found mainly on the bark, but a smaller group of about a dozen species are predominantly found on foliage. They lay their eggs mainly on the foliage and both the young stages and the adults feed on the debris and microflora on the leaf surfaces. The bark-living species feed on encrusting algae and fungal spores – see Saville (2010) for example. A large group of species are found associated with artificial environments created by the activities of people, such as stored produce, especially grains and grain products, where they feed upon fungal spores and thereby further contaminate the perishable goods with their waste. In this situation Psocoptera are generally referred to as booklice, as the species concerned are similar in appearance to other species found exploiting fungal spores from the pastes formerly used in book-binding. Other household debris may also be exploited. Most of the British (and Cornish) species also occur on mainland Europe and some of the domestic ‘booklice’ are almost cosmopolitan. There is also an Atlantic islands element to the fauna, and one which is currently expanding, presumably in response to climate change but perhaps also aided by increasing transport and commercial linkages. The recent appearance of Atlantopsocus adustus is an interesting example, otherwise only known from Madeira, the Azores and the Canary Islands. 2 SPECIAL FEATURES OF THE CORNISH FAUNA Many of the arboreal species appear to have some degree of association with old growth – sites with a long and unbroken continuity of large old open-grown trees – and this links with the well-recognised species-richness of the epiphytic lichen communities of these situations – the better developed epiphytic vegetation will provide a greater variety of opportunities for associated invertebrates. Caecilius fuscopterus, for instance, may primarily be associated with ancient oak woodlands, while the larger picture-winged Loensia and Trichadenotecnum are best known from historic parklands, old orchards and other old wood-pasture situations. Cornwall appears to have a particularly good representation of the larger species with patterned wings – ideal camouflage while at rest amongst lichens. Old heather stands may also have their own distinctive assemblage of barkflies, although this is little studied. The woody stems are a good source of encrusting algae and old stands will provide good ecological continuity of habitat. Enderleinella obsoleta may be a key species in this respect as it has so far only been found on the old heather along the bounder fields of Carn Galver, Zennor. Rock outcrops and especially sea cliffs also provide bare surfaces encrusted with epiphytes. The rare Blaste quadrimaculata may prove to be a key species for this situation, although the saxicolous fauna is not well-studied. A further important habitat type is situations with tall grassy vegetation. The rare Kolbia quisquiliarum is a speciality of this type of situation and has been found amongst tall grasses on the abandoned tin-streaming site at South Penquite Farm, Blisland The Atlantic island fauna has already been referred to and three species only recently detected in the county were originally described from Madeira, the Canary Islands and the Azores: Atlantopsocus adustus, Epicaecilius pilipennis and Trichopsocus brincki. The last two have also been turning up widely across Britain, which suggests that accidental transportation by people must be involved to some extent at least. However, A. adustus has been steadily expanding in Cornwall since it was first detected and has otherwise only been found in Sussex – this may be colonising naturally via the Atlantic air currents. A fourth species, Propsocus pulchripennis, may also fit in with this fauna as it is a widespread subtropical species known from Madeira. These are just recent arrivals of course – early colonists from the south-west would be more difficult to appreciate in such a poorly studied group. 3 SPECIES TOTALS The Cornish list currently stands at 45 species, including 28 species which are probably natives, 5 probable recent colonists, colonists, 6 introductions and 6 difficult to categorise. Additions may be expected in all three categories as the fauna here has not been well-studied in the past. The true total of natives is probably around 35 of the 50+ nationally, while the potential for further introductions is enormous. Distinguishing the three origins is however fraught with difficulty as the so-called natives colonised the area as conditions became suitable for them following natural climate change. Ectopsocus species were unknown to early recorders and so the longer-established species may be assumed to have colonised only about 100 years ago, most probably arriving with imported plant material during the Victorian period. Continual colonisation is as much a natural phenomenon as local extinction, species ranges are dynamic, responding to a wide range of variables, some natural, some clearly man-made, and the distinction is all too often indecipherable. The majority of the 26 species listed by Clark (1906) have been found subsequently, the exceptions being some of the synanthropic species. Two species named in Clark (1906) are now regarded as synonymous and it is unclear whether he was really referring to two different species. 4 EQUIPMENT FOR FIELDWORK & STUDY The most widely used piece of equipment for catching barkflies is the standard entomological sweep-net which is used to capture specimens which are otherwise invisible amongst tall vegetation or on aerial branches. Close examination of trunk bark may also reveal many species. Increasingly specialists are using the leaf-sucker devices now available from garden centres - a net securely placed across the opening of the sucker tube intercepts solid materials which can then be sorted in a tray. This technique is especially useful for leaf litter species, although sieving is another approach. A microscope is essential for the identification of most barkflies, but the experienced field naturalist can get by without one for some of the larger - and especially picture-winged - species, and a hand-lens can help a lot. The most useful general microscope is a binocular with magnification to x40, or even better x60. Some identification characters are best seen at higher magnification however and especially if slide-mounted. 5 RETENTION OF VOUCHER SPECIES As with so many invertebrate groups, the retention of voucher material and the maintenance of a reference collection are essential. Common and widespread species with which recorders can demonstrate familiarity are not a problem however, and such records are generally acceptable. Specimens for retention will normally need to be treated in some way to promote preservation. Psocoptera are relatively delicate and specimens should either be pickled in 70- 80% industrial meths or made into permanent slide mounts. For certain species it is necessary to examine genitalia and these may need to be carefully displayed in any slide mount. Information on techniques can be found in New (2005) Obviously all reference or voucher specimens need to have attached details of where found, when and by whom. Labels should be kept in the same individual pickle storage container or written onto the slide mount. 6 USEFUL LITERATURE While identification keys have been available for the British fauna for many years (New, 1974 and 2005) the regular arrival of additional species makes it advisable to have access to a copy of the European handbook (Lienhard, 1998; in French but well illustrated). New (1969a & b, 1971) provides useful introductory information on the natural history of many of the British species.