British Plant Gall Society

Verification of Gall Records
By Margaret Redfern, 2 Victoria Road, Sheffield S10 2DL

Many members of the BPGS, armed with a copy of British Plant Galls (Redfern, Shirley & Bloxham, 2011), will find that they can confidently identify most of the common galls they encounter, at least after they have had some experience. Novice cecidologists should attend as many field meetings as they can (these are advertised in the BPGS Calendar each year), where they will find more experienced people always willing to give newcomers a helping hand. Several galls have been identified by means of sending photographs to the BPGS forum – this enables other experts to view the specimen and make comments.

The publication of British Plant Galls in 2002 stimulated searches for galls and their identification, and the last few years have seen many advances in the study of galls. The 2002 edition was reprinted and included a leaflet (downloadable here) updating some names and noting some important amendments.  However, the revised edition of the keys is now published (2011) and incorporates all of these amendments and more. No doubt further changes to names will occur in the future and these will be reported in Cecidology and can be used to annotate and update the keys.

Verification

Verification is the term given to the process of checking the identification of the gall or gall causer and is the responsibility of the recorder. It may be a simple matter of identifying a common and easily recognised gall in the field and ticking the box on the Recording Sheet. However, some galls and gall causers are very difficult to identify and however experienced we become, we regularly come across galls that require determination of the causer, or for which we would like a second opinion. Similarly a very rare gall or gall causer or a new record for a county or vice county will require confirmation by an expert. As a general rule, if you are in any doubt in the field, keep a voucher specimen. Where an expert has been consulted, the expert’s (determiner’s) name will need to be added to the record so that the data manager will know that verification has been correctly carried out.

It will be assumed that all records sent in to the scheme are correct. Unfortunately, incomplete records, records with a question mark or ‘I think’ attached cannot be accepted! You can download a list of problem species requiring verification. See below for instructions on how to pack your specimens and details of where to send them.

Procedure for identifying and verifying problematic galls.

1. Identify the host plant as accurately as possible; ask a botanist friend to check it if you are unsure. (The advantage of doing fieldwork with a group of naturalists is that there is likely to be someone present who is able to check your identification.)
    
2. Identify the gall using British Plant Galls (2011); if there is a problem, consult other identification guides that you have access to, and note the references you have consulted. You may also send a photograph to the BPGS forum.
    
3. If possible, ask the opinion of a more experienced cecidologist, perhaps the Regional Coordinator for your area. You can find the Coordinators’ addresses inside the back cover of Cecidology.
    
4. If there is still a problem, especially if you suspect that the gall is uncommon or rare, send it to one of the experts listed below (all are members of the BPGS). These people will do their best to identify your gall and will consult taxonomic experts specialising in the particular group if they have problems.
   
   It is important to include as much information as possible with the gall that you send (and keep a copy of this information). You should send:
   
   
   • The unknown gall and the part of the plant it is on (leaf, twig, flower, fruit, etc.), plus an equivalent but ungalled piece of the plant (a sketch of the gall on its plant part would be useful too).
   • The name of the host plant, identified to species.
   • The date and name of the site where collected, with its vice-county and grid reference.
   • A summary of the attempts you have made to identify the gall.
   • Your name, address, telephone number plus an email address if you have one.

If you suspect that your gall is new to Britain or is a new county or vice county record, the causer must be identified and verified by a taxonomist who is expert in the group. If an insect, it may need to be reared to the adult stage. The BPGS expert to whom you send your gall will attempt to rear and identify it, or will send it to the appropriate taxonomist.

The experts will welcome problem galls – especially those that turn out to be rare or unusual or to be new records. However, please do make every attempt to identify the galls yourself before sending them on.

The keys in British Plant Galls are designed for typical galls that are mature and healthy. Even familiar ones may cause problems if they are young or if the gall causer has been parasitised, or if the gall contains inquilines; then they may be smaller than usual or enlarged and with a distorted shape. So, be aware of this and, if possible, check several individuals to find a typical gall. Most galls in the following three groups should be straightforward to identify, and should not need verification:

• Common galls that run down easily in the keys.
• Galls on oaks and roses (except for the Diplolepis pea galls on roses, the Cynips pea galls on oak leaves and the small galls on oak buds and catkins).
• Most gall wasp galls on other host plants.

The main problem groups, which should be verified and their causers determined, are:

• Galls identified tentatively in the keys or where a problem is noted.
• Rare galls and those you suspect are new to Britain or are new county records.
• Galls on host species not listed in the keys.
• Most gall midge galls in swollen or closed flowers and flower buds.
• Gall midges that cause leaves to cluster together at shoot tips in herbaceous host plants and in woody shrubs; although rosettes and artichokes on trees are better known, those on Salix caused by species of Rabdophaga often also cause problems.
• Rabdophaga galls in stems and twigs of Salix (apart from R. salicis which is well known).
• Galls on Carex and on grasses (apart from Phragmites).
• Most beetle galls.
• Many aphid galls (apart from most galls caused by Adelgidae, Pemphigus, Eriosoma and Tetraneura).

Eriophyoid mite gall taxonomy is confused on many host plants (e.g. Acer, Betula, Sorbus, Tilia, Ulmus) mainly because identification has relied on the gall with no reference to the mite. Determination of the mites will proceed slowly because there are so few expert eriophyoid taxonomists in Britain or elsewhere. For the time being, determine mite galls and their host plants as accurately as possible before making a record.

Sending specimens for verification

Pack the gall and plant carefully:

• Wrap the specimen in several layers of kitchen roll/toilet paper and, if the gall causer needs to be reared, put the specimen into a polybag – but do not put fungal galls in polybags. Fungal galls should be carefully dried to discourage mould from developing and then sent in paper bags or envelopes.
• Small and/or delicate galls, and those containing live larvae or nymphs, should be put into a small rigid container (e.g. film canister, specimen tube, small plastic or tin box).
• Ensure the specimen will be protected in the post – use bubble-wrap in a padded envelope or pack it into a box – and post it first class to the appropriate BPGS expert. Include a s.a.e. for a reply (or your email address, if available) and, if you want the specimen to be returned, include enough postage to cover this.

Where to send your specimens

The following BPGS experts are willing to verify identification of galls and their causers in the following groups (a list of their addresses follows):

• Gall midges, Cecidomyiidae: Keith Harris
• Gall wasps, Cynipidae: the galls: Peter Shirley
• Gall wasps, Cynipidae: rose bedeguar galls, their causers, inquilines and parasitoids: Robin Williams
• Gall wasps, Cynipidae: oak gall causers, inquilines and parasitoids: Robin Williams
• Galling fungi: Brian Spooner
• Galling bacteria, phytoplasmas and viruses: Brian Spooner
• Other groups, or if you have no idea to which group the gall causer belongs: Margaret Redfern

Names and addresses of experts listed above:

Dr Keith Harris, 81 Linden Way, Ripley, Woking, Surrey GU23 6LP.
Dr Margaret Redfern, 2 Victoria Road, Sheffield S10 2DL.
Peter Shirley, 72 Dagger Lane, West Bromwich, West Midlands B71 4BS.
Dr Brian Spooner, 31 Balmoral Crescent, West Molsey, Surrey KT8 1QA.
Robin Williams, Kynton’s Mead, Heath House, Wedmore, Somerset BS28 4UQ.


(This is a revised version of an article that first appeared in Cecidology, 20 (1): 6-9, in 2005)