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Leech confusions (Leech error message)The infamous blood suckers from Lacus Verbanus2 Results and Discussion
Over the past decade, I have purchased medicinal leeches from German leech
farms and from other companies in Europe (Kutschera 2004). According to the
suppliers, they were imported animals from Turkey that were cultivated and
bred in captivity. The leeches were sold as "
H. medicinalis
L. 1758", but I iden
tified all of them unequivocally as
H. verbana
Carena, 1820 (Fig. 1 A, B). We
have repeatedly co-cultivated
H. medicinalis
(animals from free-living relict
populations in Germany) and
H. verbana
in freshwater aquaria with a land area
(4–6 adult individuals of each leech species; room temperature) (Kutschera &
Wirtz, 2001). In September, the leeches produced spongy oval cocoons, laid
above the water-line, but no interbreeding occurred. Newly hatched leeches
had the species-specific colour pattern of their parents; no intermediate forms
were found. Since
H
.
medicinalis
and
H. verbana
are also distinguishable based
on molecular data (Trontelj et al. 2004, Trontelj & Utevsky 2005) it must be
concluded that they are two separate biospecies, as originally suggested by
Carena (1820) and more recently by Nesemann & Neubert (1999) and by Kut
schera (2004).
In the classical monograph on leeches by Sawyer (1986) no distinction is
made between the taxa
H. verbana
(syn.
H. officinalis
) and
H. medicinalis
. The
results summarized here show that this view is no longer acceptable.
A report on the uses of the European blood-sucking leech (
Hirudo medicina
lis
) for medical purposes, with a brief summary of contemporary leech trade
and farming, was recently published in a leading international journal (Pilcher
2004). The "return of the blood suckers" is described in detail, but, unfortu
nately, the author referred to and depicted the wrong leech species. The "hard-
working" laboratory animals described in this essay and other recent articles
(see, for instance, Jauker & Clauss 2003) are the descendants of the infamous
blood-suckers from
Lacus Verbanus
and not "true" European medicinal leeches.
It should be added that in all modern biology textbooks I have inspected so far
this "leech confusion" is documented, i. e., the authors usually depict
H. verba
na
Carena, 1820 under the pseudonym
H. medicinalis
L. 1758 (see, for instance,
Sawyer 1986, p. 571, Campbell & Reece 2002, p. 660 and Ludwig 2003, p. 144).
3 Conclusions
Current European conservation legislation (Bern Convention, EU Habitat Di
rective, CITES, IUCN) include
H. medicinalis
, but the taxon
H. verbana
is not
mentioned in these documents. Today, the leeches discovered in the 18th cen
tury in
Lacus Verbanus
are still widely distributed in some regions of South
eastern Europe and Turkey (Nesemann & Neubert 1999, Trontelj et al. 2004).
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