Guidelines for future gyrodactylid descriptions
Comments on previous descriptions
Gyrodactylid species descriptions present a number of problems which can, in extreme cases, make re-identification of the species concerned, almost impossible. This is primarily a problem with older species descriptions, but can also apply to more up-to-date descriptions. Phenotypic descriptions of gyrodactylids have largely been restricted to the size and form of three hard structures (the sclerites) in the attachment apparatus, i.e. hamuli, marginal hook, ventral bar. In the last decade this traditional taxonomical approach has been supplemented with molecular data, particularly sequencing of the Internal Transcribed Spacers (ITS), and more recently the mitochondrial cytchrome oxidase 1 (COI) gene. Genetic examination of paratypes with subsequent submission of the results in GenBank upon descriptions of new species seems essential for future gyro-taxonomy.
To avoid future problems, we propose the following
guidelines for good practice for gyrodactylid descriptions.
In future, acceptance of records into the GyroDb project will depend upon these recommendations being followed.
For further information on problems with older Gyrodactylus descriptions, and the need for adequate descriptions, see this page.
Parasite species description should include the following information:
Ideally, diagnosis should also include:
- Parasite Family and genus;
- Parasite Species;
- Etymology of the new species names;
- Host species (age/sizes/sex). If host taxonomy is known to be problematic, voucher specimens to be deposited;
- Date of collection / collector of host and parasites;
- Host locality(ies), where possible with grid reference or GPS co-ordinates;
- Location (site, microhabitat) on host;
- Level of infection;
- Water temperature;
- Number of specimens examined from each host locality / site;
- Morphological description. This should be based on a single specimen which is subsequently designated the holotype. Taxonomically significant features of this specimen should be illustrated. Range of dimensions and other characters to be obtained from a series of one or more paratypes. The total number of specimens examined should be given;
- The description should be illustrated with measurements/landmarks used, in addition to drawings (LM) of one or more paratypes. Univariate or multivariate statistical data (e.g. mean ± SD (range) of selected characters;
- Number and condition of holotype and paratypes (or syntypes), with information on which museum has been chosen for deposition of specimens. Accession numbers should be included in the final description. If no molecular analyses have been undertaken, ethanol-fixed specimens should be deposited for future genetic studies;
- MorphoBank (when established) accession numbers;
- Genbank accession number where appropriate.
and where available:
- Genetic differences related to Internal Transcribed Spacer (ITS) regions of the rDNA cassette and sequence information on Cytochrome Oxidase 1 (COI). This latter allows articulation of gyrodactylid systematics with the international Barcoding Initiative (www.barcoding.si.edu);
- Number of specimens genetically examined from each host locality / site;
- Sequence data where possible (at least ITS).
- Comments on the intraspecific variability (ecological, morphological or genetic);
- Ecological differences related to host / level of host specificity;
- Ecological differences releated to site;
- Morphological differences related to pharynx / penis;
- Morphological differences related to the sclerites in the attachment organ.
Finally: results and description (when accepted for publication) should be sent to GyroDBase
Several of the informational units can be presented in different ways. However, it is desirable that all new descriptions are (1) sufficient for future comparisons, especially by making voucher specimens available for genetic studies at a museum; and (2) that the continuous development in taxonomic methodology is quickly and efficiently communicated globally. In these respects, GyroDBase may play a key role in the future of global gyrodactylid taxonomy.