UK Tachyine Beetles (Coleoptera: Carabidae) With Special Reference to the Status of Tachys Edmondsi Moore
Total Page：16
File Type：pdf, Size：1020Kb
Report Number 465 UK tachyine beetles (Coleoptera: Carabidae) withspecial reference to the status of Tachys edmondsi Moore English Nature Research Reports working today for nature tomorrow English Nature Research Reports Number 465 UK tachyine beetles (Coleoptera: Carabidae) with special reference to the status of Tachys edmondsi Moore Peter M. Hammond The Natural History Museum, London You may reproduce as many additional copies of this report as you like, provided such copies stipulate that copyright remains with English Nature, Northminster House, Peterborough PE1 1UA ISSN 0967-876X © Copyright English Nature 2002 Summary ‘Edmonds’ Ground Beetle’ is one of six tiny ground beetles (Coleoptera: Carabidae) of the genus Tachys (in the broad sense) known to be resident in the UK First described from the New Forest area in 1934, where it was collected in various years between 1912 and 1937, it has never been recorded from elsewhere in the UK or from any other country. In this latter respect it is unique amongst British Carabidae. Although one of several putatively endemic terrestrial macro-invertebrate species subject to fairly detailed appraisal by Hammond (1996), the status of Tachys edmondsi has remained “something of an enigma”. Hammond (l.c.) noted that, although the conditions in which the species had been found in the New Forest “do not immediately point to an introduction . this cannot be ruled out”. However, Tachys edmondsi continues to be listed, eg in the UK Biodiversity Action Plan, as an UK endemic species. To further assess its status and, in particular, to seek to clarify whether it owes its presence in the UK to introduction, perhaps from far afield, a thorough search of the literature and of the extensive collections of tachyine ground-beetles held in The Natural History Museum, London, was undertaken. Examination of the hundreds of named species of Tachyina (ie members of the genus Tachys and related genera), of some thousands of named and un-named specimens of Paratachys, the subgenus (or genus) to which Tachys edmondsi proves to belong, and many published descriptions, uncovered no evidence that T. edmondsi has an extra-European origin. Indeed, all known taxa of the immediate species-group to which T. edmondsi turns out to belong appear to be native to the Palaearctic region and principally its western part. Unfortunately, current taxonomic understanding of this species-group, which includes two other British species – Tachys bistriatus and Tachys micros – is extremely poor. The investigation revealed much confusion in the naming of species, especially in the Mediterranean and neighbouring areas where many species of the group are found. There appear to be a number of as yet undescribed species in the group, several of which are represented in the collections of The Natural History Museum. A thorough taxonomic revision of the whole group is evidently needed but, equally clearly, this would be a major undertaking. Despite these difficulties, evidence that Tachys edmondsi is native to the western part of the Palaearctic region and does, in fact, occur in parts of Western Europe other than Britain, did emerge from the investigation. First, previously un-named specimens – from Spain and from Morocco – provisionally regarded as belonging to this species were located in The Natural History Museum collections. Second, if UK specimens of T. edmondsi are run through various published keys to members of its species-group that occur in France, Spain and Morocco, they run to other named taxa that have been described from those countries. Third, close examination of the original and other descriptions of various of these exotic species reveals few or no substantial points of difference with T. edmondsi. Three named taxa, in particular, present themselves as likely candidates to belong to the same species as T. edmondsi. These are Tachys kabylianus, described by Puel (1935) from Algeria and (apparently) France, Eotachys bistriatus ssp. obtusiusculus, described by Jeannel (1941) from France, and Eotachys otini, described by Antoine (1943) from Morocco. The type material of these and of other taxa that are possibly synonymous with T. edmondsi is deposited in a range of European museum collections, and not all of the material necessary for an appraisal has been gathered together as yet. Once fully assembled, this material will be carefully studied. There is a reasonable expectation that T. edmondsi will then be confirmed as a species present in countries other than the UK. It is also likely that T. edmondsi, a name dating from 1956, will prove to be preoccupied by a name (eg one or more of those listed above) of greater age. In line with current European and North American usage, the species should also be referred to the genus Paratachys Casey. Paratachys edmondsi thus appears to be a species native to the UK that on the evidence emerging, as well as a priori (see discussion in Hammond, 1996), is not endemic to the British Isles. However, the condition of its flight wings suggests that it may be a poor disperser, collection data suggest that it may be extremely fastidious in its habitat requirements, and its rarity in collections suggests that it may be very patchily distributed throughout its range. On present evidence this may encompass parts of France, Spain, Morocco, Algeria and perhaps some neighbouring countries, but is unlikely to extend to Central Europe or, apart from the UK, to Northern Europe. Whatever the precise situation, UK populations are probably of a relict type and they may well be quite distant from the nearest extant populations on the European mainland. Against this background, a high UK conservation status continues to be appropriate for the species. The first task, after an interval of more than 60 years since the species was last collected in the UK, remains to rediscover T. edmondsi in its (former) New Forest haunts. In the course of work on the status of Paratachys edmondsi a number of new findings were made with respect to the taxonomy, nomenclature and distribution of other species of Tachyina. A summary of those findings that are of particular relevance to the UK fauna are included in this report. These include a record of a single individual found at Bookham Common, Surrey, of a species (probably Paratachys pallidulus (Antoine)) not previously known from the British Isles. Recommendations for the future with respect to (1) nomenclature of British species of Tachyina, and (2) rarity/threat statuses appropriate for each of them, are also included. Contents Acknowledgements Summary 1. Background....................................................................................................................9 2. Introduction....................................................................................................................9 3. History of study of UK Tachyina (= Tachys sensu lato) .............................................10 4. Current classification and nimenclature of Tachyina with special reference to western Palaearctic species..........................................................................................11 4.1 Classification and nomenclature above the species level ................................11 4.2 Taxonomy and nomenclature of European Tachys and related genera ...........14 4.3 Species identification in the genus Paratachys Casey.....................................15 5. Identity and status of Paratachys edmondsi (Moore)..................................................16 6. Distribution and biology of the species of Tachyina recorded from the UK and neighbouring countries.................................................................................................20 7. Conclusions and recommendations..............................................................................28 8. Acknowledgments........................................................................................................29 9. References....................................................................................................................29 Appendix 1. List of Paratachys species, including all those examined while investigating the status and identity of P. edmondsi Moore..................................................35 Appendix 2. Locality data for British specimens of Tachyina (= Tachys sensu lato) in the collections of The Natural History Museum, London. ..............................41 1. Background Tachys edmondsi (“Edmonds’ Ground Beetle”) is listed in the UK Biodiversity Action Plan as a supposed UK endemic species. It is known from relatively few specimens, all collected from a small area of the New Forest bogs. Last known to have been found in 1937, repeated searches over recent years have failed to relocate it. In a recent English Nature contracted report (Hammond, 1996), it was suggested that Tachys edmondsi is unlikely to be endemic in the UK, and that it could be a temporarily established non-indigenous species. To check the latter possibility, a comprehensive search among Tachys species from other parts of the world would be needed. Should Tachys edmondsi turn out to be an immigrant from far afield any allocation of resources to its conservation would not be justified. Against this background, I was commissioned to carry out taxonomic investigations to clarify the status of Tachys edmondsi. To this end, all possible close relatives and species of similar appearance to T. edmondsi were examined, using the collections of named and un-named