by Martin Harvey and Mark G. Telfer
|The Mordellidae (or Tumbling Flower-beetles) are routinely found on flowers such as umbellifers. In the sweep-net or on the beating tray they tuck their appendages in and lie on their sides (see photo) or skip and tumble about until they make it over the edge of the beating tray. They have a superficial resemblance to the members of the genus Anaspis (Scraptiidae) but are generally larger and have the abdomen ending in a long point (absent in Anaspis). Some species are associated with dead wood, others mine the stems of perennial herbs.|
|Identification of some species in this family is difficult. And the fact that they are so extraordinarily difficult to card doesn’t help. It is best to keep all glue off the hind legs and to have the maxillary palps and antennae showing. But to card a mordellid as in the photo to the left is a fight against the natural tendency of the specimen to lie on its side with its head and all its appendages tucked in. Specimens which have been given at least a few days in dilute acetic acid will be easier to manipulate.
This is a small (17 species) but taxonomically difficult family and it is possible that further species occur in Britain but have yet to be recognised.
Details of the techniques for catching, preparing and mounting mordellids may be found in these references:
- Levey, B. (2006). Mordellidae. Pp. 110 – 111 in Cooter, J. and Barclay, M. (eds) A coleopterist’s handbook (4th edition). Orpington: The Amateur Entomologists’ Society.
- Batten, R. (1988). Mordellidae (Coleoptera): catching, preparing and mounting. EIS Nieuwsbrief, 18: 9-10. A more detailed account, which can be obtained from the Netherlands Centre for Biodiversity Naturalis
The current checklist of beetles of the British Isles (Duff 2008, downloadable from The Coleopterist) lists 17 species in family Mordellidae, in five genera. Fifteen of these species are keyed out in Batten (1986), but there have been some confusing changes in nomenclature as well as the two additions to the British list since Batten’s key was published. The relevant papers are listed here, and at the foot of the page is a table of the British species and the papers in which they can be found.
The most nearly complete key to the British species is Batten (1986), which has all except Mordellistena pygmaeola and Mordellistena secreta:
- Batten, R. (1986). A review of the British Mordellidae (Coleoptera). Entomologist’s Gazette, 37: 225-235.
The two species missing from Batten (1986) are described in:
- Cooter, J. (1991). Mordellistena pygmeola Ermisch, 1956 (Coleoptera: Mordellidae) new to Britain. Entomologist’s Gazette, 42: 97-98.
- Levey, B. (1999). Mordellistena secreta Horák (Coleoptera: Mordellidae), a species new to Britain. British Journal of Entomology and Natural History, 12: 227-229.
Mordellistena neuwaldeggiana, M. humeralis and M. variegata: this difficult trio can be identified with these papers:
- Levey, B. (2011). A review of the British Mordellistena species (Mordellidae) related to M. humeralis Linnaeus. The Coleopterist, 20: 119 – 124. Excellent identification paper.
- Telfer, M.G. (2011). Identification of Mordellistena neuwaldeggiana, humeralis and variegata. Version 3 (11th Feb. 2012). [Click to download PDF.] Includes a postscript on Mordellistena rufifrons which may occur in Britain.
- Allen, A.A. (1995b). On the British Mordellistena humeralis (L.) (Col.: Mordellidae) and its allies. Entomologist’s Record and Journal of Variation, 107: 181-184. [Notes on variety of colour forms in M. humeralis, and key separating M. humeralis, M. neuwaldeggiana and M. variegata.]
These two papers provide additional keys and illustrations for other tricky groups within the family:
- Levey, B. (2002). A revision of the British species of Mordellistena (Coleoptera, Mordellidae) belonging to the parvula group and the subgenus Pseudomordellina Ermisch. British Journal of Entomology and Natural History, 15: 83-90.
- Allen, A.A. (1986). On the British species of Mordellistena Costa (Col. Mordellidae) resembling parvula Gyll. Entomologist’s Record and Journal of Variation, 98: 47-50. [As an identification work, this has been completely superseded by Levey (2002).]
A pdf key (in Dutch) to the Dutch species of Mordellidae, including genitalia illustrations for Mordellistena pygmaeola, is also available:
- Batten, R. (1976). De Nederlandse soorten van de keverfamilie Mordellidae. [The Dutch species of the beetle family Mordellidae.] Zoologische Budragen, 19.
Papers describing species that were believed to be further additions to the British list but that have subsequently been synonymised with existing species:
- Allen, A.A. (1995a). An apparently new species of Mordellistena (Col.: Mordellidae) in Britain. Entomologist’s Record and Journal of Variation, 107: 25-26. [This describes Mordellistena imitatrix, subsequently shown in Levey (2002) to be synonymous with Mordellistena acuticollis.]
- Allen, A.A. (1999). Another new species of Mordellistena Costa (Col. Mordellidae) in Britain. Entomologist’s Record and Journal of Variation, 111: 205-206. [This describes Mordellistena eludens, subsequently shown in Levey (2002) to be synonymous with Mordellistena pseudoparvula.]
The species now known as Mordellistena pseudoparvula, has had a particularly confused history. The first record to be published was by A.A. Allen who collected a single female at Shooters Hill, SE London on 1st July 1985. On the basis of this specimen it was included in Batten’s (1986) key and added to the British list by Allen (1986), both authors using the name parvuloides. However, the species had already been recorded in Britain: John Owen had been given a Malaise trap sample from Santon Downham, Norfolk taken in August 1983 containing a single male and had had its identity confirmed by Dr Batten as pseudoparvula. Owen (1999) published details of the earlier British record and reported that parvuloides should be treated as a synonym of pseudoparvula. Later that year, Allen (1999) described a new species (Mordellistena eludens) which Levey (2002) showed to be synonymous with pseudoparvula.
- Owen, J.A. (1999). Mordellistena pseudoparvula Ermisch (Col.: Mordellidae) new to Britain. Entomologist’s Record and Journal of Variation,111: 101-102.
Identification sources for the British species of Mordellidae: for a table of all the British species of Mordellidae, showing which literature references they can be identified with, see this PDF (version 3: 11th Feb. 2012). The PDF also includes the British conservation statuses of each species and a table of additional species which might yet be found in Britain.