Fauna Europaea: Annelida – Hirudinea, incl. Acanthobdellea and Branchiobdellea

Abstract Fauna Europaea provides a public web-service with an index of scientific names (including important synonyms) of all living European land and freshwater animals, their geographical distribution at country level (up to the Urals, excluding the Caucasus region), and some additional information. The Fauna Europaea project covers about 230,000 taxonomic names, including 130,000 accepted species and 14,000 accepted subspecies, which is much more than the originally projected number of 100,000 species. This represents a huge effort by more than 400 contributing specialists throughout Europe and is a unique (standard) reference suitable for many users in science, government, industry, nature conservation and education. Hirudinea is a fairly small group of Annelida, with about 680 described species, most of which live in freshwater habitats, but several species are (sub)terrestrial or marine. In the Fauna Europaea database the taxon is represented by 87 species in 6 families. Two closely related groups, currently treated as distinct lineages within the Annelida, are the Acanthobdellea (2 species worldwide, of which 1 in Europe) and the Branchiobdellea (about 140 species worldwide, of which 10 in Europe). This paper includes a complete list of European taxa belonging to the Hirudinea, Acanthobdellea and Branchiobdellea. Recent research on a limited number of taxa suggests that our current appreciation of species diversity of Hirudinea in Europe is still provisional: on the one hand, cryptic, unrecognised taxa are expected to emerge; on the other, the status of some taxa currently treated as distinct species deserves revisiting.


Introduction
The European Commission published the European Community Biodiversity Strategy, providing a framework for development of Community policies and instruments in order to comply with the Convention on Biological Diversity. This Strategy recognises the current incomplete state of knowledge at all levels concerning biodiversity, which is a constraint on the successful implementation of the Convention. Fauna Europaea contributes to this Strategy by supporting one of the main themes: to identify and catalogue the components of European biodiversity into a database in order to serve as a basic tool for science and conservation policies.
With regard to biodiversity in Europe, both science and policies depend on a knowledge of its components. The assessment of biodiversity, monitoring changes, sustainable exploitation of biodiversity, and much legislative work depend upon a validated overview of taxonomic biodiversity. Towards this end Fauna Europaea plays a major role, providing a web-based information infrastructure with an index of scientific names (including important synonyms; i.e. alternative names still in use, or at lead found in recent literature) of all living European land and freshwater animals, their geographical distribution at country level and some additional useful information. In this sense, the Fauna Europaea database provides a unique reference for many user-groups such as scientists, governments, industries, conservation communities and educational programs.
Fauna Europaea started in 2000 as an EC-FP5 four-year project, delivering its first release in 2004. After thirteen years of steady progress, in order to improve the dissemination of Fauna Europaea results and to increase the general awareness and acknowledgement of Fauna Europaea contributors, novel e-Publishing tools have been used to prepare data papers of all 58 major taxonomic groups (Jong et al. 2014).

Data-papers & gap-analysis
In order to improve the dissemination and citation of Fauna Europaea and to increase the acknowledge of the Fauna Europaea contributors, a special Biodiversity Data Journal Series has been compiled using novel e-Publishing tools, called Contributions on Fauna Europaea, preparing data-papers of all major Fauna Europaea taxonomic groups. This work was initiated during the ViBRANT project and is further supported by the recently started EU BON project. This contribution represents the first publication of the Fauna Europaea Annelida-Hirudinea data sector as a BDJ data paper.
In the EU BON project ) also further steps will be made on implementing Fauna Europaea as a basic tool for biodiversity research and for taxonomic expertise evaluation and management in Europe, using Fauna Europaea as a standard reference for taxonomic Information. The Fauna Europaea data-papers will contribute to a quality assessement on biodiversity data by providing estimates on gaps in taxonomic information and knowledge (see Table 1). The Annelida-Hirudinea, together with their allies Acanthobdellea and Branchiobdellea, are one of the 58 Fauna Europaea major taxonomic groups, covering 98 species (Fig. 2). The data were acquired and checked by two specialists (Tables 1, 2). Table 1.
Responsible specialists per family in Annelida-Hirudinea. Addititional information: The Hirudinea or leeches form a quite small group of macrophagous or blood-sucking annelids, including about 680 species (Sket and Trontelj 2008), probably derived from a lineage of freshwater oligochaetes. Their presence in the sea, and in terrestrial habitats, is secondary, following a primary radiation in freshwater habitats. About 15% of the ca. 680 species described thus far (Sket and Trontelj 2008), including many representatives of the Piscicolidae and all members of the Ozobranchidae, are marine; ca. 100 species (all members of the Americobdellidae, Cylicobdellidae, Haemadipsidae, Xerobdellidae, a few Hirudinidae and one member of the Salifidae) are terrestrial or semiterrestrial, all the remaining Hirudinea live in freshwater habitats. Three main feeding styles can be recognized among the leeches. The Rhynchobdellida, represented in the continental fauna of Europe by members of the Glossiphoniidae (Fig. 3) and the Piscicolidae, are provided with a stiff protrusible proboscis through which they pierce the skin of their preys (cold-and warm-blooded vertebrates, mollusks, insect larvae) and suck their body fluids or tissues; within the Arhynchobdellida, many representatives of the Hirudiniformes (in Europe, those of the family Hirudinidae) are provided with toothed muscular 'mandibles' used to produce superficial wounds in the skin of their vertebrate hosts, the blood of which they feed on, while those of other families (in Europe, Haemopidae and Xerobdellidae (Fig. 4), and also the Erpobdelliformes (only family Erpodbellidae native in Europe) are macrophagous and ingest whole preys, e.g. insect larvae, crustaceans, oligochaetes. Most leeches are temporary ectoparasites, their contact with their hosts being limited to the feeding phase, but many members of the Rhynchobdellida live more ore less permanently attached. All leeches are hermaphrodite. Large species may suck human blood. Hirudo spp. have been traditionally used in medicine.
The Annelida-Hirudinea database in Fauna Europaea includes also information on two smaller annelid groups, the Branchiobdellea and the Acanthobdellea, often treated in the past as members of the Hirudinea, in which case the true leeches (i.e., the Hirudinea of most current classifications) are often renamed Euhirudinea (e.g., Siddall et al. 2001). Today, the Hirudinea (in strict sense, corresponding to Euhirudinea of other classifications), Branchiobdellea and Acanthobdellea are treated by most authorities as distinct lineages within the clitellate annelids, alongside the taxa traditionally grouped as the Oligochaeta, Acanthobdellea and Branchiobdellea. All Branchiobdellea, ca. 140 species worldwide , are small (1-12 mm) freshwater worms that live on crustaceans, mainly crayfish. The Acanthobdellea, 2 species of cold riverine waters, are parasitic on fish, mainly salmon. Table 2.
Molecular phylogenetic studies have heavily impacted on the internal classification of the Hirudinea (e.g., Borda and Siddall 2004) and more progress is expected from further studies. Detailed molecular systematics studies have shown gross errors in the traditional delineation of leech species, including the case of the European medicinal leech -a concept under which other species must be recognized besides Hirudo medicinalis Linnaeus, 1758 (Trontelj andUtevsky 2005). On the other hand, reproductive isolation seems not to be completed between lineages currently treated as distinct species, such as within the same group of species (S. Utevsky, pers. com.). Discrepancies between the results of morphological vs. molecular systematic analyses have also been noted in other groups, as in the endemic lineage of Dina species inhabiting Lake Ochrid (Trajanovski et al. 2010) and future reassessments are likely to increase the number of taxa worth recognition at the species level.
A revised delineation of genera and families is also suggested by a first molecular taxonomic study on Branchiobdellea (Williams et al. 2013).

Project description
Title: This BDJ data paper includes the taxonomic indexing efforts in Fauna Europaea on European Annelida-Hirudinea covering the first two versions of Fauna Europaea worked on between 2000 and 2013 (up to version 2.6).

Personel:
The taxonomic framework of Fauna Europaea includes partner institutes, providing taxonomic expertise and information, and expert networks taking care of data collation.
Every taxonomic group is covered by at least one Group Coordinator responsible for the supervision and integrated input of taxonomic and distributional data for a particular group. The Fauna Europaea checklist would not have reached its current level of completion without the input from several groups of specialists. The formal responsibility of collating and delivering the data of relevant families rested with a number of Taxonomic Specialists

Sampling methods
Study extent: See spatial coverage and geographic coverage descriptions.
Sampling description: Fauna Europaea data have been assembled by principal taxonomic experts, based on their individual expertise, including literature sources, collection research, and field observations. In total no less than 476 experts contributed taxonomic and/or faunistic information to Fauna Europaea. The vast majority of the experts are from Europe (including EU non-member states). As a unique feature, Fauna Europaea funds were set aside for rewarding/compensating for the work of taxonomic specialists and group coordinators.
To facilitate data transfer and data import, sophisticated on-line (web interfaces) and offline (spreadsheets) data-entry routines were built, integrated within an underlying central Fauna Europaea transaction database (see Fig. 5).
A first release of the Fauna Europaea index via the web-portal has been presented on the 27 of September 2004, the most recent release (version 2.6.2) was launched on the 29th August 2013. An overview of Fauna Europaea releases can be found here: http:// www.faunaeur.org/about_fauna_versions.php.
Quality control: Fauna Europaea data are unique in the sense that they are fully expertbased. Selecting leading experts for all groups assured the systematic reliability and consistency of the Fauna Europaea data.
Furthermore, all Fauna Europaea data sets are intensively reviewed at regional and thematic validation meetings, at review sessions on taxonomic symposia (for some groups), by Fauna Europaea Focal Points (during the FaEu-NAS and PESI projects) and by various end-users sending annotations using the web form at the web-portal. Additional validation on gaps and correct spelling was effected at the validation office in Paris.
In conclusion, in general we expect to get taxonomic data for 99.3% of the known European fauna. The faunistic coverage is not quite as good, but is nevertheless 90-95% of the total fauna. For the Annelida-Hirudinea (this paper) the taxonomic coverage is 100% (see Table 1), but the distribution by country is still incomplete, especially for the Branchiobdellea.
Checks on technical and logical correctness of the data have been implemented in the data entry tools, including around 50 "Taxonomic Integrity Rules". This validation tool proved to be of huge value for both the experts and project management, and contributed significantly to preparation of a remarkably clean and consistent data set. This thorough reviewing makes Fauna Europaea the most scrutinised data sets in its domain.
Step description: By evaluating team structure and life cycle procedures (data-entry, validation, updating, etc.), clear definitions of roles of users and user-groups, according to the taxonomic framework were established, including ownership and read and writes privileges, and their changes during the project life-cycle. In addition, guidelines on common data exchange formats and codes have been issued (see also the 'Guidelines for Experts' document).  Fig. 1).

Geographic coverage
The focus is on species (or subspecies) of European animals of terrestrial and freshwater environments. Species in brackish waters, occupying the marine/freshwater or marine/ terrestrial transition zones, are generally excluded.

Taxonomic coverage
Description: The Fauna Europaea database contains the scientific names of all living European land and freshwater animal species, including numerous infra-groups and synonyms. More details about the conceptual background of Fauna Europaea and standards followed are described above and in the project description paper(s).
All species described to date are included in the current version of the data base. We may expect a future increase of species numbers for Erpobdellidae (ca 10 or even more species), and perhaps one or two species in other families, e.g. Glossiphoniidae and Piscicolidae (see Table 1). A reliable assessment of the expected number of species is not feasible at present for the Branchiobdellidae.   FaEu Annelida-Hirudinea species per family. See Table 1 for family statistics. Notes: Currently living animals in stable populations, largely excluding (1) rare/irregular immigrants, intruder or invader species, (2) accidental or deliberate releases of exotic (pet) species, (3) domesticated animals, (4) foreign species imported and released for biocontrol or (5) foreign species largely confined to hothouses.   Fauna Europaea on-line (browser interfaces) and off-line (spreadsheets) data entry tools.