ENTOMOLOGIST'S MONTHLY MAGAZINE 219 NEW AND LITTLE-KNOWN BRITISH XYELIDAE AND TENTHREDINIDAE (HYMENOPTERA, SYMPHYTA) BY ANDREW D. LISTON & STEPHAN M. BLANK ABSTRACT First records from the British Isles ofzyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONM Xyela curva Benson (Xyelidae), Heterarthrus cuneifrons Altenhofer & Zombori and Pseudodineura mentiens (Thomson) (Tenthredinidae) are presented. X. curva is also recorded as new to Belgium. These are introduced sawflies with endophytic larvae on hostplants long established in British forestry and horticulture. The status of Pontania myrsiniticola Kopalke, 1991 as an indigenous gall- maker in the Scottish Highlands is confirmed. INTRODUCTION A revised checklist of British Symphyta is now being prepared by D. Sheppard. The four sawflies mentioned below should be included in this. Three are endophytic monophages on plants which have been deliberately introduced to the British Isles for afforestation, amenity or horticultural purposes. Initial indications are that these insects are at least locally established in widely separated regions of East England and Scotland. Their presence raises many questions about when and how they first appeared, and how widely they now occur. Rather than speculating using the veiy restricted data presented below, we wish only to observe that all the hostplants involved have already been present in Britain for at least two hundred and fifty years, so that the dates of introduction of the sawflies will probably now be very difficult to establish with any precision. Attention is also drawn to the occurrence in the Highlands of Pontania myrsiniticola as a native species, with a distinctive shape of gall intermediate between that of the P. viminalis species-group and those of the P. crassipes and aquilonis species-groups. Although this sawfly has already been mentioned from Scotland, no precise localities have so far been published. MATERIAL AND METHODS The following abbreviations are used for the names of collections in which voucher specimens are deposited: DEI = Deutsches Entomologisches Institut, Müncheberg; ISNB = Institut royal des Sciences naturelles de Belgique, Departement d'Entomologie, Brussels; RSME = National Museums of Scotland, Edinburgh. Xyela curva was identified by SMB during his research on the Xyelidae, in jmaginal material caught with a Malaise trap in East Anglia. The other species were recorded in Scotland and England by ADL based on larvae, leaf-mines and galls. Nomenclature follows Taeger & Blank (2005). 27th October, 2006 Vol. 142 (2006)