Hirudo sanguisuga, (Linnaeus, 1758)

Šatkauskienė, Ingrida & Rutkauskaitė-Sucilienė, Jurgita, 2022, The present state of the leech fauna (Annelida: Hirudinea) in Lithuania, Zootaxa 5115 (1), pp. 47-62 : 57-59

Haemopis sanguisuga ( Linnaeus, 1758)

( Figure 6W )

Material examined: Maišia (Nr. 15), n=7, vii–viii.2019; Baltieji Lakajai (Nr. 22), n=3, 5.viii.2018; Lampėdžiai (Nr. 37), n=2, 11.ix. 2019. Didžiulis (Nr. 28), n=3, 18.vi.2019; Ilgis (Nr. 33), n=2, 21.viii.2018.

Diagnosis: Vermiform, large leech. 120–130 mm length and 8–9 mm width. Dark green or almost black leech. Ventral surface is lighter. Similar to H. medicinalis but doesn’t exhibit lateral yellow lines ( Fig. 6W ) ( Maitland et al. 2000). Five pairs of eyespots arranged in parabolic arc.

Habitat: Haemopis sanguisuga was found in stagnant or almost stagnant water bodies Mud bottom, flourished vegetation and water rich by organic material are preferred by this species.

Distribution: Haemopis sanguisuga inhabits in all Palearctic regions and is a common and widespread in European countries ( Farzali and Saglam 2020). Haemopis sanguisuga was found only in few localities ( Table 1 ).

In total, 12 species of freshwater leeches are recorded in the present study, leeches belong to 4 suborders ( Erpobdelliformes , Hirudiniformes , Glossiphoniiformes and Oceanobdelliformes ), 5 families: Haemopidae (1 species), Hirudinidae (1 species), Glossiphoniidae (6 species), Erpodellidae (3 species), and Piscicolidae (1 species). Erpobdella octoculata and Glossiphonia complanata were the most common and were found in 61 % and 34 % of studied sites, respectively. Both of these species were collected in stagnant and flowing water. Our findings are in agreement with previous authors, which showed that the type of body water is not important for the distribution of these species ( Moroz and Lipinskaya 2017).

Furthermore, two European rare leech species were found during this study, supplementing their known distribution and representing new records within Lithuania. One of these is the European medicinal leech Hirudo medicinalis classified as “near threatened” in the IUCN Red List in many European countries ( Surugiu 2018; Kutschera and Shain 2019). Two localities of H. medicinalis were recorded during our study, confirming the status of rare of this species in Lithuania. The second rare species is Erpobdella monostriata, which was found only in eastern part of country ( Fig. 1 ). Utevsky et al. (2015) reported the occurrence of this species in Denmark, Germany, Sweden, Poland, the Netherlands, Russia, Belarus, and Lithuania. In Germany E. monostriata has the status vulnerable ( Jueg and Zettler 2015).

Our findings reported here, confirm the presence of some leech species that were recorded previously, in particular in the Curonian lagoon, Lithuania: Szidat (1926), Gasiūnas (1959) and Zettler and Daunys (2007). Zettler and Daunys (2007) investigated the macrozoobenthos in Curonian lagoon and beside of other invertebrates, recorded a total of 21 species of leeches. A variety of rare leech species were recorded by Zettler and Daunys (2004): Batracobdelloides moogi Nesemann and Csányi, known only from a few places of Europe (Grosser and Pešić 2005), Erpobdella lineata (O.F. Müller) ( Bielecki et al. 2011b), Caspiobdella fadejewi (Epshtein), Piscicola pawlowskii (Sket) and Piscicola pojmanskae Bielecki. Any of these species were recorded in the present study.

The first records of E. octoculata and E. nigricollis in Lithuania Curonian lagoon were published by Szidat (1926). Later, E octoculata, E. nigricollis, E. testacea Savigny, E. monostriata and Erpobdella lineata were reported in findings from 1951 to 1957 ( Gasiūnas 1959) and 2004 ( Zettler and Daunys 2007). The summary of all published records of leeches from the Curonian Lagoon from 1921 to 2004, reach 21 species, belonging to families Glossiphoniidae, Erpobdelidae, Piscicolidae , Hirudinidae .

In contrast with the high leech diversity found in previous studies in Curonian lagoon, only E. octoculata and G. complanata were found in our study. Potential explanations for this discrepancy can be identified as follows: (1) unequal number of surveyed sites. The previous study focused only on Curonian lagoon and surveyed several sampling sites. In contrast to our study that was focused on various regions of Lithuania. (2) different time of sampling. The authors of the previous study collected their samples in September, when the water begins to cool after the summer and is therefore suitable for majority invertebrates, including leeches. Meanwhile in our study, leeches were studied in the middle of the summer, in July, when the water temperature in littoral was about 21– 23.80 C. By avoiding such temperatures, the leeches possibly retreated from surface layers. (3) Change of leech communities over time as a response to environmental factors. An explanation of the change in species over 15 years should be confirmed or rejected in future studies.

Furthermore, additional field work is necessary to determine the prevalence of Haemopis sanguisuga , which is considered a common European species. Finding of H. sanguisuga in Curonian lagoon was mentioned by Szidat (1926) and Gasiūnas (1959), however Zettler ( Zettler and Daunys 2007) failed to collect this species in Curonian lagoon. In the current study, H. sanguisuga was found only in 4 lakes and 1 stream from 41 investigated water sites. The rare occurrence in Lithuania of a European common species makes it necessary to perform additional studies in the future to allow a more accurate assessment of the status of the species.

Currently, the number of leech species recorded in Lithuania (including previous records) is 21 species, arranged in 14 genera and 5 families. For the confirmation of this list of leech species, and in particularly for rare species, additional surveys should be conducted in areas that were surveyed 15 years ago. It is clear the diversity of the leeches from Lithuania is far from complete. High number of species recorded in neighboring countries, for example 47 species recorded in Poland ( Bielecki et al. 2011b) clearly suggests that the number of leech species in Lithuania should be higher.

Figures

FIGURE 1. Sampling stations of freshwater leeches in Lithuania.

FIGURE 6. Freshwater leeches in Lithuania:dorsal view of Hirudo medicinalis (T), dorsal papillae (showed by arrow) (U), lateral–ventral view of the body (V); W–lateral view of Haemopis sanguisuga with male copulatory organ outside of the body.