Introduction

Until this year, most British bryologists would have thought of Conocephalum conicum as one of the most straightforward liverworts to identify – large, conspicuous and without taxonomic complications. However, a very thorough recent paper by Szweykowski et al. (2005) has shown that there are two species of Conocephalum in Europe, both of which occur in Britain. These are the typical C. conicum (L.) Dumort. and a second plant which they described as a new species, C. salebrosum Szweykowski, Buczkowska & Odrzykosli. These species were originally distinguished by isozyme studies. Fortunately a detailed examination of herbarium specimens and of cultivated material has revealed some morphological distinctions between the two taxa that allow them to be identified, even in the field.

Although Szweykowski et al. (2005) confirmed the presence of both species in Britain, checking both the isozymes and the morphology of a few specimens, there are as yet few records from our area. Since August 2005 we have seen both species in both Britain and Ireland, and our very preliminary observations suggest that most material can be identified without undue difficulty. Recent field experience has also revealed that the two taxa can coexist at the same locality, often in close proximity to one another, but populations of each species also occur independently. We think that the best way of investigating the distribution and ecology of the species here is to ask field bryologists to collect information from as wide an area of Britain and Ireland as possible. To do this, the BBS Conservation & Recording Committee have agreed to our suggestion of a ‘mini-survey’ of Conocephalum. The aims of the survey are:

1. to confirm that C. conicum and C. salebrosum can be distinguished in our area and check the characters used by Szweykowski et al. (2005) to separate them
2. to establish the vice-comital distribution of the two species
3. to produce provisional maps of their distribution in the 10-km squares of Britain and Ireland
4. to investigate the ecology and reproductive features of the two species with a view to highlighting any differences between them.

In this survey, we are just as interested in records of C. conicum as we are in those of the new species C. salebrosum.

The differences between the species set out in Table 1 are based on information published by Szweykowski et al. (2005), plus a few of our own measurements and observations. The characters are therefore based to a large extent on material from outside our area. Photographs of the two taxa are shown on the Conocephalum image page. In the field the dull surface of the C. salebrosum thallus with a more reticulate pattern provides the best way of distinguishing it C. conicum, which has a markedly shiny surface.

The microscopic differences between the two species are illustrated in Szweykowski et al. (2005), and this paper can be downloaded.

Both species are dioicous, and we hope to obtain information on the frequency of male and female plants, as well as sporophytes. Tubers have also been recently observed in both taxa; they are found most often on the ventral surface of moribund parts of thalli, either on the parent plant or among rhizoids and soil debris. A tuber is illustrated in Paton (1999) and further detail is provided by Paton (1993).

Taking part in the survey

We are asking bryologists to visit Conocephalum sites, to record the details on a Recording Sheet and to send us a fresh sample of the plant with the completed Sheet. The Sheets can be obtained from us or downloaded as a sheet for 2 records (pdf) or a sheet for 3 records (pdf). An example of a completed Recording Sheet is also shown. To split the workload we have each taken responsibility for different areas:

• Northumberland , Scotland (v.cc. 67-68, 72-112) David Long
• N Wales , N England , Man (v.cc. 47-52, 57-66, 69-71) Tim Blackstock
• SW England, S Wales, Ireland (v.cc. 1-6, 33-35, 41-46, H1-40) Sam Bosanquet
• Rest of England , Channel Islands (v.cc. 7-32, 36-40, 53-56, C) Chris Preston

Please send your material to the appropriate address (at head of this article), although there is no need to stick rigidly to these area reps if it is inconvenient to do so. If one weekend you collect several specimens from one region and a single specimen just over the border, for example, you might as well send them all to the person who is responsible for the main region in which you have collected. It is important to send material of C. conicum as well as C. salebrosum, as we would like to see as much comparative material as possible, and voucher specimens of both species will be needed for a revision of the vice-comital distribution. In sending fresh material, make sure that the plants are not too wet and, if possible, put them in a package which protects them from crushing in the post.

Interim results of the survey will appear on the BBS website, so you will be able to see where collections are still needed. If the species prove fairly easy to identify there may come a time when the area rep tells you that you need not send any more vouchers from those vice-counties in which you have already collected a voucher specimen.

The survey will continue until December 2006.

References

Paton JA. 1993. Tubers on Conocephalum conicum (L.) Lindb. thalli. Journal of Bryology 17: 503-505.

Paton JA. 1999. The liverwort flora of the British Isles. Colchester: Harley Books.

Szweykowski J, Buczkowska K, Odrzykoski IJ. 2005. Conocephalum salebrosum (Marchantiopsida, Conocephalaceae) - a new Holarctic liverwort species. Plant Systematics and Evolution 253: 133-158. pdf file