First Report of Branchiobdella kozarovi SUBCHEV, 1978 (Annelida: Clitellata) from the Western Bulgaria, with Remarks on its Recent Distribution

Biljana Rimcheska1,2, Vanja Marković1, Marija Ilić1, Valentina Slavevska-Stamenković2, Svetoslav Cheshmedjiev3, Katarina Zorić1, Bela Csányi4, Momir Paunović1, Mitko Subchev5


1 University of Belgrade, Institute for Biological Research "Siniša Stanković", Despota Stefana Boulevard 142, 11000 Belgrade, Serbia; E-mail: This e-mail address is being protected from spambots. You need JavaScript enabled to view it

2 Institute of Biology, Faculty of Natural Science and Mathematics, Ss. Cyril and Methodius University, P.O. Box 162, 1000 Skopje, Republic of Macedonia

3 SI Eco Consult Ltd., Sofia, Bulgaria

4 Danube Research Institute, Centre for Ecological Research, MTA (Hungarian Academy of Sciences), Göd H-2131, Hungary

5 Institute of Biodiversity and Ecosystem Research, Bulgarian Academy of Sciences, 2 Yurii Gagarin Str., 1113-Sofia, Bulgaria



A total of 336 Branchiobdella kozarovi (Subchev, 1978) were found as a part of the invertebrate investigation conducted in the vulnerable "wetland "Choklyovo Blato"" wetland (western Bulgaria) in October 2015. The collected branchiobdellid worms, found on three female Astacus leptodactylus (Eschscholtz, 1823), present the westernmost finding of this species on the Balkan Peninsula. In addition, the recent distribution of B. kozarovi is discussed.

Keywords: Branchiobdella kozarovi, narrow-clawed crayfish, recent distribution, Balkan Peninsula.



Among eight west-palearctic representatives of the genus Branchiobdella (Odier, 1823) known so far, B. kozarovi (Subchev, 1978) is one of the latest described species (Subchev, 2014). The species was described from branchiobdellidians found on crayfishes collected in a man-made pond near the village of Razdelna, Varna district (Subchev, 1978). Redescription of its reproductive system was done by Gelder et al. (1994). Later B. kozarovi was found in three new localities in Bulgaria all of them situated in the eastern and north-eastern part of Bulgaria. Of these three localities two were situated on the Danube and one was on a river flowing into the Black Sea (Subchev and Stanimirova, 1998). After these findings (from 1984 to 1986) this species was not reported in Bulgaria until now.

Here we report on a new locality of B. kozarovi in western Bulgaria.


Materials and Methods

A hydrobiological field sampling of macro-invertebrates of the wetland "Choklyovo Blato" (western Bulgaria: N 42°24'4.70", E 22°49'29.48", 864 m.a.s.l.) was conducted on October 12th, 2015. The "Choklyovo Blato" is a mountainous wetland situated 50 km south-west from the Bulgarian capital city, Sofia. It should be noted that this wetland is assessed as vulnerable on a national level (Michev and Stoyneva, 2007).

The sampling was done by standard benthological hand-net. The content of the hand-net was water-washed in a bucket. Some larger captured macroinvertebrate specimens, including three female Astacus leptodactylus (Eschscholtz, 1823) were identified in situ and then released unharmed. The collected macroinvertebrate material was preserved in an 80% ethanol solution.


Results and Discussion

A total of 336 branchiobdellid specimens were recorded during the laboratory processing of collected material from "Choklyovo Blato". By the body form and dimensions, as well as the shape of the jaws (Subchev, 1978; 2014), all the worms were identified as B. kozarovi. Knowing that the branchiobdellidans are exclusively epibionts on crayfishes, it could be reasonable to assume that the branchiobdellid worms found by us were washed from the captured A. leptodactylus crayfishes.

According to Boshko (2010) B. kozarovi has Caspian origin following the origin of its exclusive host A. leptodactylus. Ponto-Caspian drainages belong to Euro-Mediterranean Subregion, as the subregion of the Holarctic zoogeographical region (Bânârescu 1990). The fact that A. leptodactylus has been recorded in almost all water basins in the Ukraine, allowed Boshko (2005) to conclude that this country could be considered as the center of B. kozarovi areal . Further records on B. kozarovi in the Ukraine (Kolesnikova, 2006; 2007; Kolesnykova et al., 2008) supported this statement (Figure 1). Fard and Gelder (2011) reported B. kozarovi on A. leptodactylus from northwestern Iran and presented an overview of its distribution. They suggested that the peripheral locations of B. kozarovi could be a result of a commercial introduction of its specific host, A. leptodactylus, illustrating this statement with the presence of this branchiobdellid species in Poland (Śmietana and Wierzbicka 1999). The same authors supposed that as a result of the common use of A. leptodactylus in aquaculture and food production in the majority of the Euro-Mediterranean countries, B. kozarovi should be distributed more widely in this region. The recent finding of B. kozarovi in the Netherlands (Kolesnikova et al., 2012), Romania and Belarus (Subchev, 2013) (Figure 1) strongly support this assumption. Having in mind that the presence of A. leptodactylus has been confirmed in many localities in almost all Western European countries (excluding only a few, e.g. Spain, Portugal, Norway and Sweden; (Souty-Crosset et al., 2006) there is a "lot of room" for the possible presence of B. kozarovi. However, for unknown reasons, lack of data regarding this branchiobdellid worm includes even countries which almost fully or partially are situated in the area of the original distribution of A. leptodactylus (according to Souty-Crosset et al., 2006), and furthermore which branchiobdellid fauna is well studied, as Hungary (Kovács, Juhász. 2007) or Croatia (Klobučar et al., 2006). According to Fard and Gelder (2011) Iran should be regarded as part of the endemic range of both B. kozarovi and its host, A. leptodactylus. However, this contradicts the fact that Iran, as well as the Asian part of neighboring Turkey, where B. kozarovi was also recently found (Subchev and Gelder, 2010; Subchev, 2012), is not considered to be a part of the native range of A. leptodactylus, as it was described by Souty-Crosset et al. (2006).

After the description of B. kozarovi collected on crayfishes in the man-made pond near the Razdelna (Varna district), three new localities of this species were reported in Bulgaria – two of them from the Danube River and one from the Veleka River, a Black Sea tributary (Subchev and Stanimirova, 1998) (Figure 1). It should be noted that the crayfishes collected in Razdelna, the terra typica of B. kozarovi, had been introduced from the Beli Lom River, near the village of Gorotzvet (Subchev, 1978) and accordingly this locality, although it had never been investigated for crayfishes and branchiobdellidans, could be added to the known localities of the species in Bulgaria. By our present finding the known range of B. kozarovi on the Balkan Peninsula has expanded westward (Figure 1). However, it should be noted that the new locality of this species reported here is most certainly a result of a secondary introduction of the B. kozarovi host – the "Choklyovo blato" was drained in the 1970s but restored and recultivated in the 1980s (Kozhuharov, personal communication).


Figure 1: Recent distribution of B. kozarovi: The grey dots represent the localities previously marked by Fard and Gelder (2011); the black dots represent the newest findings of B. kozarovi (Kolesnykova et al., 2012; Subchev, 2013). On the map of Bulgaria the empty dot represents our new finding; ? – the locality was not investigated (see the text).




The study was carried out as part of the 'Actualization of typology and classification system for assessment of surface water bodies from categories "rivers", "lakes" and "transitional waters" in the period of the First River Basin Management Plans' project, financed by the Bulgarian Government. Additionally, the study was supported by the UNESCO/KEIZO OBUCHI RESEARCH FELLOWSHIPS PROGRAMME (UNESCO/Japan Young Researchers' Fellowship Programme), Cycle 2015, Japan Funds-in-Trust Project (REF.: ERI/MSP/PPF/ LZF/15.037). We would like to thank Dimitar Kozhuharov, from the Faculty of Biology, University of Sofia, Bulgaria, for valuable information regarding the history of "Choklyovo Blato".



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