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Article

Trematode Parasite Infections in Freshwater Leeches from the Central Region of Lithuania: First Record of Posthodiplostomum (Dubois, 1936) in a Leech Host

by
Jurgita Rutkauskaitė-Sucilienė
,
Loreta Griciuvienė
,
Baltramiejus Jakštys
and
Ingrida Šatkauskienė
*
Faculty of Natural Sciences, Vytautas Magnus University, K. Donelaičio 58, LT-44248 Kaunas, Lithuania
*
Author to whom correspondence should be addressed.
Diversity 2025, 17(2), 117; https://doi.org/10.3390/d17020117
Submission received: 13 January 2025 / Revised: 31 January 2025 / Accepted: 3 February 2025 / Published: 5 February 2025
(This article belongs to the Section Freshwater Biodiversity)
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Abstract

:
Leeches play a critical role in the transmission of digenean trematodes, yet their parasitic infections remain understudied in the Baltic region. This study investigates the diversity, prevalence, and molecular identification of trematode infections in freshwater leeches from central Lithuania. A total of five leech species (Alboglossiphonia heteroclita, Glossiphonia complanata, Glossiphonia verrucata, Helobdella stagnalis, and Erpobdella octoculata) were examined using compression and dissection techniques to detect trematode cysts, which were predominantly found in the soft tissues rather than the intestinal tract. Molecular sequencing of 18S rRNA, COI, and ITS markers, combined with phylogenetic analyses, confirmed the presence of three trematode genera: Cotylurus, Australapatemon, and Posthodiplostomum. The overall infection rate among leeches was 40.8%, with the highest prevalence observed in G. complanata (53.3%). Cotylurus spp. were the most frequently detected parasites, with genetic analyses revealing close affinities to Cotylurus syrius and Cotylurus spp. from Poland. Australapatemon species were also identified, though species-level classification remained inconclusive. Notably, this study provides the first molecular evidence of Posthodiplostomum cuticola utilizing leeches as intermediate hosts, extending the known range of hosts for this trematode. Phylogenetic analyses demonstrated the broad geographic distribution of these parasites, with close genetic matches to isolates from Poland, Russia, Canada, and Japan. The findings highlight the ecological significance of leeches in parasite transmission networks and contribute to the understanding of trematode diversity and host interactions in the Baltic region. Further molecular and ecological studies are needed to clarify species diversity and the role of leeches in the life cycles of aquatic parasites.

1. Introduction

The Leeches, a diverse group of annelids, inhabit various aquatic environments worldwide and play vital ecological roles. As integral members of freshwater ecosystems, they function as predators, scavengers, and prey for numerous invertebrates and vertebrates. Furthermore, leeches act as both hosts and vectors for a variety of parasites [1,2,3,4], making parasitic infections in leeches a significant but often underexplored aspect of aquatic ecology.
This study investigates parasitic infections in several species of freshwater leeches sampled from water bodies in the central region of Lithuania: Alboglossiphonia heteroclita (O. F. Müller, 1774), Glossiphonia complanata (Linnaeus, 1758), Glossiphonia verrucata (F. Mueller 1844), Helobdella stagnalis (Linnaeus, 1758), and Erpobdella octoculata (Linnaeus, 1758). These species reflect their ecological diversity, varied feeding strategies, and distribution, which collectively provide a comprehensive framework for understanding parasite–host dynamics. E. octoculata, H. stagnalis, and G. complanata are broadly distributed across Lithuania and Europe, making them ideal for studying regional parasite dynamics. Their different feeding behaviours—predatory and scavenging habits in H. stagnalis and E. octoculata versus hematophagy in Glossiphoniidae (Vaillant, 1890) species—offer unique insights into how ecological niches influence parasitic infections.
Preliminary observations and the literature suggest that species from the families Erpobdellidae (Blanchard, 1894) and Glossiphoniidae host a diverse array of parasites, including protozoans, helminths, and other parasitic invertebrates [5,6,7,8,9,10]. These parasites, with their varied life cycles and ecological impacts, indirectly affect the health of other aquatic organisms, including economically important fish species. While found leeches themselves do not interact directly with humans, their role in aquatic ecosystems underscores their ecological significance.
In this study, we examined parasitic infection parameters in these species of leeches, including prevalence and infection intensity across surveyed water bodies. Parasite life stages were identified using molecular sequence data for three markers: 18S ribosomal RNA (18S rRNA), cytochrome c oxidase subunit I (COI), and internal transcribed spacer (ITS). Phylogenetic analyses were conducted to compare these sequences with GenBank data, confirming the distinct status of the genera Australapatemon (Sudarikov, 1959), Cotylurus (Szidat, 1928), and Posthodiplostomum (Dubois, 1936). Additionally, we provide novel data on the distribution of Posthodiplostomum cuticola (von Nordmann, 1832) in leeches, contributing to a deeper understanding of parasite–host relationships in freshwater ecosystems.

2. Materials and Methods

From April 2022 to September 2024, 771 leeches were collected from Nemunas River (3 sampling sites), Neris River (2 sampling sites), and Maišia (a river delta where standing water dominates, but there is flowing water in the middle) (Table 1 and Table 2) in Kaunas region, a central part of Lithuania. Leeches were collected by hand picking, observing submerged objects like stones, woods, and vegetation, using the entomological net and homemade aluminium traps with chicken liver as bait. The leeches were transferred to plastic buckets with water, transported to the laboratory, and stored in the fridge until necropsy. Species were identified according to Timm et al. [11] and Bielecki et al. [12]. After anaesthesia and euthanasia, 320 specimens of E. octoculata, 278 of H. stagnalis, 90 of Glossiphonia complanata, 19 of Alboglossiphonia heteroclite, and 4 of G. verucata were dissected and examined under a stereomicroscope (Stemi305, Zeiss) and light microscope with a camera (Primostar 3, Zeiss). The leeches were compressed between two objective glasses to observe internal structures and detect parasites. Subsequently, a longitudinal incision was performed on the dorsal side, carefully exposing the soft tissue (musculocutaneous and botryoidal (as previously described [13]), which is the primary site of cyst localization. The found metacercarias were extracted alive from the body, washed in physiological sodium chloride solution, and fixed in 70% ethanol for molecular identification.
The following parasitological parameters were calculated: the prevalence of the parasite [14,15] and the intensity of the infection (the number of parasites in the host) [16].
Prevalence was categorized according to Munn [17]: low prevalence (less than 10% of the host population is infected); moderate prevalence (10%–30% of the host population is infected); high prevalence (30%–50% of the host population is infected); very high prevalence (more than 50% of the host population is infected).
The Chi-square test was used to compare infection rates between different species, while the Kruskal–Wallis test was applied to compare parasite intensity (average number of parasites) counts across species.
DNA extraction and PCRs were performed on randomly selected individual metacercaria using the “Phire Animal Tissue Direct PCR Master Mix” commercial kit, following the manufacturer’s protocol (Thermo Fisher Scientific, #F-170S, Waltham, MA, USA). Each metacercaria was placed in a tube with 20 μL of dilution buffer; 0.5 μL of DNA Release Additive was then added. The contents were gently mixed by vortexing, and the tube was kept at room temperature for 2–5 min before being placed on a heating pad at 98 °C for 2 min. The supernatant containing the parasite DNA was subsequently used for analysis.
The parasite species was identified molecularly by analysing the 28S nuclear ribosomal RNA (28S rRNA), cytochrome c oxidase subunit I (COI), and partial internal transcribed spacer (ITS) regions. Primers were selected based on previously published studies [10] (Table 3).
The PCR results were visualized following electrophoresis on a 1.5% agarose gel. When non-specific amplification was detected, electrophoresis products were purified using the “GeneJET™ Gel Extraction Kit” (Thermo Fisher Scientific, Vilnius, Lithuania), according to the manufacturer’s protocol. All PCR products were sent to a sequencing service (Macrogen, Amsterdam, The Netherlands) where sequencing was performed in both directions.
The sequences obtained in the present study were analysed using the BLAST algorithm to confirm the morphological identification of parasite species and were aligned with sequences available in GenBank using the ClustalW multiple alignments [18] in MEGA X [19].
Sequences of the partial 28S rRNA, COI gene, and ITS2 region were aligned in three independent datasets. The representative sequences were submitted to GenBank under the accession numbers PQ373558–PQ373559 for the Cotylurus sp. and PQ373611 for the Posthodiplostomum cuticola 28S rRNA gene, PQ45826 and PQ462293 for the Cotylurus sp., PQ459958 for the Australapatemon sp., PQ460009 for the Posthodiplostomum cuticola COI gene, and PQ374201 for the Posthodiplostomum cuticola ITS2 region.
The phylogenetic relationships between the sequences were constructed using the maximum likelihood method [20] and the Tamura–Nei parameter model in MEGA X. The best-fitting nucleotide substitution models: HKY + G for 28S rRNA, HKY + G + I for COI, and HKY for ITS were determined using the Bayesian Information Criterion (BIC) with jModelTest v2.1.10 [21].

3. Results

3.1. Molecular Identification of Parasites

3.1.1. 28S rRNA Region

The partial sequences of the 28S rRNA gene region were successfully obtained from trematode metacercariae of two leech species (Glossiphonia complanata and Helobdella stagnalis). The sequences obtained during the study were compared with other leech trematode metacercariae sequences from the Gene Bank (Figure 1). Two sequences from Lithuania (PQ373558, PQ373559) shared 99.9% to 100% similarity with Cotylurus syrius (Dubois, 1934) and Cotylurus sp. (Szidat, 1928) from GenBank. The phylogenetic analysis confirmed the taxonomic affiliation of the studied samples to the genus Cotylurus. Both sequences clustered within a clade containing sequences from trematode metacercariae identified as Cotylurus syrius (MW244647), isolated from a mute swan (Cygnus olor) in Poland, and Cotylurus sp. (MW244646), isolated from a leech Haemopis sanguisuga (Linnaeus 1758) in Poland. The formation of different clades in the phylogenetic tree revealed the molecular diversity within the genus Cotylurus. A comparison of the sequences used in the phylogenetic analysis indicated distinct positions for Cotylurus raabei (Bezubik, 1958), Cotylurus marcogliesei n. sp., and Cotylurus hebraicus (Dubois, 1934) within the genus. The other sequence in this study (PQ373611), from the leech trematode metacercariae, showed 99.92% homology with Posthodiplostomum cuticola (von Nordmann, 1832), an isolate from nightshade (Nycticorax nycticorax) (MZ710955) in Ukraine.

3.1.2. COI Gene

The partial sequences of the COI gene were successfully obtained from trematode metacercariae found in three leech species (Glossiphonia complanata, Helobdella stagnalis, and Erpobdella octoculata). Phylogenetic analysis of the metacercariae from the leeches revealed the presence of three genera: Cotylurus, Australapatemon (Sudarikov, 1959), and Posthodiplostomum (Dubois, 1936) (Figure 2). The Australapatemon clade includes sequences of Australapatemon sp. from Poland and Australapatemon burti (Miller, 1923) from Russia. The Posthodiplostomum clade comprises a single species P. cuticola. Sequence (PQ460009) also falls close to this clade but is more closely related to Australapatemon sp. The Cotylurus clade is well supported and includes Cotylus syrius, Cotylurus marcogliesei, and Cotylurus sp. The sequences (PQ458261 and PQ462293) identified in the current study fall within this clade.
One sequence (PQ462293) obtained in this study grouped with sequences identified as Cotylurus sp. from Japan, Cotylurus syrius from Poland, and Cotylurus marcogliesei from Canada, sharing a similarity of 99.71–99.74%. The second isolate (PQ458261) shared the highest similarity (99.68%) with Cotylurus sp., isolated from the leech Haemopis sanguisuga (MW204816) in Poland. The third sequence obtained in this study (PQ460009) derived from the metacercariae of leech trematodes shared 98.96% homology with Posthodiplostomum cuticola isolated from nightshade (Nycticorax nycticorax) (MK089346) in the Czech Republic. The fourth sequence (PQ459958) grouped with trematode sequences identified as Australapatemon sp., derived from the leech Haemopis sanguisuga (MW204824, MW204826, MW204827, MW204828, and MW204829) in Poland and from the snail Planorbis planorbis (OQ658623), as well as Australapatemon burti, isolated from the mollusc Planorbis planorbis (OP715848) in Russia.

3.1.3. ITS Region

The DNA sequence of the ITS2 fragment from metacercariae sampled from leeches in the present study shared 100% similarity with sequences of Posthodiplostomum cuticola from Scardinius erythrophthalmus, Rutilus rutilus, and Abramis brama from Hungary, as well as from Anisus vortex, Alburnus alburnus, and Abramis brama from Denmark, and from Chana argus from Japan (Figure 3). Sequences from Lithuania, Hungary, and Denmark formed one clade.

3.2. Prevalence of Parasitic Infections in the Examined Leech Species

Three genera of trematodes belonging to the family Strigeidae (Railliet, 1919) were found in leeches and identified: Cotylurus, Australapatemon, and Posthodiplostomum. The latter genus and determined species, Posthodiplostomum cuticola, are a new record in the study of leeches.
Among 771 sampled leeches, 317 were infected with at least one of the three parasite species, resulting in an overall prevalence of 40.8% (Table 1).
Leech-specific prevalence of parasites revealed a notably high infection rate of 53.3% in Glossiphonia complanata, with 48 infected individuals out of 90 examined. In Erpobdella octoculata, the infection rate was 49.4%, with 159 infected out of 320 examined. Helobdella stagnalis showed a prevalence of 33.8%, with 94 infected out of 278 examined. The prevalence in Glossiphonia verrucata was 75.0% (three infected out of four examined), but this finding should be interpreted cautiously due to the small sample size (Table 2).
The Chi-square test indicated a statistically significant association between species and infection rates (p < 0.05). However, the intensity of infection did not differ significantly between the various species of leeches, with average infection rates per individual ranging from 1.5 to 46.2 (see Table 1). The highest number of metacercariae found in a single individual was 112, observed in Glossiphonia complanate (see Table 2).
Cotylurus sp. was identified as the dominant parasite across all species of leeches (see Table 1). The prevalence of Cotylurus was 94.1% in Erpobdella octoculata and 93.6% in Helobdella stagnalis.
Australapatemon sp. was found to vary from 2.08% in G. complanata to 33.33% in G. verrucata and 50% in Theromyzon tessulatum. However, the last two species should be assessed with caution due to the low number of examined individuals.
Posthodiplostomum cuticola was found in 2.08% of G. complanata and 0.62% of E. octoculata. Additionally, 6.25% of G. complanata and 1.06% of H. stagnalis were coinfected with both P. cuticola and Cotylurus. Cotylurus was identified in 279 leeches across all surveyed water bodies, with the highest number of infections recorded in Maišia, where 221 infected individuals were found out of 235 examined (see Table 1). Coinfection involving all three parasites—Australopatemon, Cotylurus, and Posthodiplostomum—was observed in individual cases of G. verucata and G. complanata.

3.3. Distribution of Parasites Across Surveyed Water Bodies

The infection rates of each parasite (P, A, C) were assessed across the examined water bodies. The Chi-square test for independence revealed that the differences in infection rates among the three sites are statistically significant (p < 0.001). The highest prevalence of metacercariae, at 64.5%, was recorded in the Nemunas River, where 78 out of 121 leeches were infected. In Maišia, nearly half of the sampled leeches were infected (39.7%), while only 2 out of 58 sampled leeches (3.44%) were infected in the Neris River.
Infection by Cotylurus was detected in all surveyed water bodies, with the highest number of individuals found in Maišia, where 221 out of 235 leeches were infected. Additionally, other infections and coinfections by the parasites Australapatemon and Posthodiplostomum cuticola were observed in both Maišia and the Nemunas River; however, the prevalence of these parasites was not significant compared to Cotylurus.

4. Discussion

Our findings revealed that leeches studied in the central region of Lithuania are infected by the digenean trematodes Cotylurus, Australapatemon, and Posthodiplostomum. We established a significant infection rate of 40.8% among the leeches, with the highest prevalence of infection occurring in Glossiphonia complanata (53.3%). Cotylurus sp. was identified as the most common parasite in examined leeches. Cotylurus is a genus of trematodes within the family Strigeidae, comprising species that parasitize aquatic birds and utilize freshwater snails and leeches as intermediate hosts [8,20]. In Poland, several Cotylurus species (Cotylurus cornutus (Rudolphi, 1809), C. syrius, and C. strigeoides) have been documented [8]. In agreement with previous studies [22,23], we found that G. complanata and E. octoculata, in particular, were infected with this parasite, meaning that they are significant second intermediate hosts harbouring metacercariae of species like Cotylurus strigeoides and/or C. cornutus.
Recent molecular studies conducted by Pyrka et al. [22] have identified significant genetic diversity among Cotylurus species in Poland. Our analysis, based on 28S rRNA gene sequences and comparisons with sequences in GenBank, revealed the closest matches to Cotylurus syrius and Cotylurus sp. from Poland (see Figure 1). According to Pyrka, both C. cornutus and C. syrius exhibit multiple distinct lineages, indicating a species complex rather than a single taxonomic entity. Therefore, the complexity within the Cotylurus genus highlights the need for detailed genetic analyses to precisely define species boundaries.
The second parasite identified in leeches in this study was Australapatemon. Parasites of the genus Australapatemon are found in various regions of Europe and throughout North and South America, primarily infecting birds in the Anatidae family [24,25]. Their intermediate hosts include snails and leeches [26,27,28,29,30]. Currently, there are ten recognized species of Australapatemon [31]. However, the specific species in our study could not be conclusively determined. GenBank comparisons indicated the closest matches to other Australapatemon species, with one potential identification being Australapatemon burti. Given the presence of Australapatemon species in Poland, including A. burti and A. minor (Yamaguti, 1933) [10], it is plausible that the specimens found in our study belong to a known species.
Future research should focus on expanding genetic databases for Australapatemon, utilizing both nuclear and mitochondrial markers to improve species-level identification. Additionally, comprehensive morphological studies and sampling across diverse geographic areas and host species could help clarify the taxonomy and ecology of this genus.
The third genus of parasites found in leeches is Posthodiplostomum. Morphological and phylogenetic analyses based on markers such as 28S rRNA, COI, and ITS2 region sequences revealed a 100% match with Posthodiplostomum cuticola (see Figure 1, Figure 2 and Figure 3). To the best of our knowledge, Posthodiplostomum cuticola is the first strigeid reported to infect leeches, which extends the known range of intermediate hosts for Posthodiplostomum within the Strigeidae family. Posthodiplostomum cuticola has a complex life cycle, typical of digenean trematodes, with the first intermediate host of freshwater snails (Lymnaea species, Radix species). Cercariae of parasites are released from snails to water and penetrate to a second intermediate host (freshwater fish). Metacercariae encyst in the tissue of fish, and heavily infected fish may exhibit visible cysts (black spots) on their skin, a condition often called “black spot disease”. Definitive hosts usually are piscivorous birds (like herons, cormorants, gulls, and other wading or waterfowl species). Birds ingest infected fish, where the metacercariae develop into adult worms in the intestines, completing their life cycle. Posthodiplostomum cuticola is widely distributed across Europe. It has been well documented in Croatia (where it affects various cyprinid fish species [32]), Poland [33,34], and Hungary [35]. The findings in our study extend the range of the potential hosts for this trematode.
Analysis of phylogenetic trees (Figure 1, Figure 2 and Figure 3) from current and previous studies reveals a diversity of geographical locations for the sequences of the parasites, including Poland (PL), Russia (RU), New Zealand (NZ), the Czech Republic (CZ), Japan (JP), Canada (CA), Ukraine (UA), Mexico (MX), United States of America (USA), Denmark (DN), and Hungary (HU) (Table 4). Observed diversity highlights the broad distribution of these parasitic species, and the variety of hosts (birds as a host for several species of Australapatemon and Cotylurus and fish as the main hosts for the majority of Posthodiplostomum species) demonstrates the ecological adaptability and range of these digenean parasites.
The high prevalence of parasites in leeches observed in this study confirms that leeches are important hosts or vectors for various stages of trematode development. Leeches, which are typical members of shallow freshwater communities, share their habitats with snails, insect larvae, crustaceans, juvenile fish, amphibians, and birds. They serve as a crucial link for the transmission of parasites between snails, which are often the primary intermediate hosts, and definitive hosts, such as birds, mammals, or amphibians.
The leech species G. complanata is hematophagous, feeding on a variety of definitive hosts, including amphibians, birds, and fish. These leeches often carry various parasitic species, including trematodes. Additionally, G. complanata may have an immune system that tolerates high parasitic loads, allowing it to serve as a reservoir for a wide variety of trematodes and other parasites. This tolerance may represent an evolutionary adaptation to its parasitic or ectocommensal lifestyle.
In contrast, E. octoculata is a scavenger that feeds on dead or decaying material, and it may ingest stages of parasites such as Cotylurus from infected intermediate hosts or eggs shed into the water by aquatic birds, which serve as common definitive hosts. Additionally, Helobdella stagnalis, primarily a freshwater predator, feeds on oligochaetes, insect larvae, and aquatic snails [36,37]. Notably, H. stagnalis has been observed exhibiting facultative parasitism in amphibians, as reported by [38]. Our findings are consistent with other studies [39,40], indicating that H. stagnalis has a high prevalence of infection. This is largely due to its habitat preferences and feeding behaviour, which increases its exposure to cercariae released by infected snails [39,40]. Cercariae penetrate the epidermis of leeches and develop into metacercariae within their tissues. The physiological environment within leeches offers suitable conditions for the growth and maturation of trematodes. Consistently, during our dissections, trematode cysts were primarily located in the parenchyma rather than within the intestinal tract. This observation corresponds with previous research, which found that metacercariae predominantly encyst in the parenchyma and musculature of leeches. For example, a study of leeches as intermediate hosts for strigeid trematodes detected metacercariae in the parenchyma and musculature of 40.5% of leeches examined, with an average intensity of 19.9 cysts per infected leech [10]. Similarly, Apatemon gracilis metacercariae have been reported to encyst primarily in the posterior half of their leech hosts [41]. Our findings reinforce these observations, as trematode cysts were consistently found in the soft tissues of leeches, particularly within the parenchyma and musculature. This supports the focus of our dissections on these areas rather than the intestinal tract.
Table 4. List of sequences of strigeids obtained in this study. A—adult; M—metacercaria; C—cercaria; DS—daughter sporocyst; PL—Poland; JP—Japan; CA—Canada; UA—Ukraine; MX—Mexico; CZ—Czech Republic; USA—United States of America; DN—Denmark; HN—Hungary; RS—Russia.
Table 4. List of sequences of strigeids obtained in this study. A—adult; M—metacercaria; C—cercaria; DS—daughter sporocyst; PL—Poland; JP—Japan; CA—Canada; UA—Ukraine; MX—Mexico; CZ—Czech Republic; USA—United States of America; DN—Denmark; HN—Hungary; RS—Russia.
Digenean TaxaIsolateReferenceStageHost SpeciesLocalityGenBank Number
28SCOIITS
Cotylurus sp.NS129[42]DSRadix auriculariaJPLC599505
Cotylurus sp.NS008[42]DSRadix auriculariaJPLC599507
Cotylurus sp.NS071[42]DSRadix auriculariaJPLC599504
C. syriusLD[10]ACygnus olorPLMW244648
C. hebraicus1492[10]AFulica atraPLMW244639
C. syriusLK[10]ACygnus olorPLMW244647
Cotylurus sp.PG9[10]MHaemopis sanguisugaPLMW244646
C. raabeiS2[10]AAnas platyrhynchosPLMW244649
Cotylurus sp.RL_G_102a[10]MPeregriana labiataPLOM949867
Cotylurus sp.BU_S_162[10]MRadix auriculariaPLOM949869
Cotylurus sp.BU_S_149[10]MRadix auriculariaPLOM949868
C. marcoglieseiS.IN.Lc.MTL.2.5[43]ALophodytes cucullatusCAMH521248
P. cuticolaVT6731[44]-Nycticorax nycticoraxUAMZ710955
Posthodiplostomum sp.1408[45]-Nannopterum brasilianusMXMF398330
Posthodiplostomum sp.1408[45]-Nannopterum brasilianusMXMF398331
P. brevicaudatumPBPF1[46]MPerca fluviatilisCZKX931426
P. centrarchiX0891[47]-Lepomis gibbosusUSAOM638425
P. cf anterovariumX0893[48]-Lepomis gibbosusUSAOM688205
Australapatemon sp.PG1[10]MHaemopis sanguisugaPL MW204826
Australapatemon sp.PG5[10]MHaemopis sanguisugaPL MW204829
Australapatemon sp.PG2[10]MHaemopis sanguisugaPL MW204827
Australapatemon sp.PS5A[10]MHaemopis sanguisugaPL MW204824
Australapatemon sp.PG4[10]MHaemopis sanguisugaPL MW204828
A. burti-[49]CPlanorbis planorbisRS OP715848
Australapatemon sp.ZP536[50]DSPlanorbis planorbisPL OQ658623
Posthodiplostomum sp.DNA3265[51]-Amatitlania siquiaMX OK314928
P. cuticola-[52]-Ardea cinereaCZ MK089346
C. syriusLD[10]ACygnus olorPL MW204819
C. marcoglieseiS.IN.Lc.MTL.2.5[43]ALophodytes cucullatusCA MH536509
Cotylurus sp.NS015[42]DSRadix auriculariaJP LC599699
Cotylurus sp.NS007[40]DSRadix auriculariaJP LC599701
Cotylurus sp.PG6[10]MHaemopis sanguisugaPL MW204816
P. cuticolaPD27_its[35]-Scardinius erythrophthalmusHN MN080292
P. cuticolaPD26_its[35]-Scardinius erythrophthalmusHN MN080291
P. cuticolaPD24_its[35]-Rutilus rutilusHN MN080289
P. cuticolaPD15_its[35]-Abramis bramaHN MN080286
P. cuticolaPD12_its[35]-Abramis bramaHN MN080285
P. cuticolaFu145[53]MAnisus vortexDN MW001117
P. cuticola01_2[54]MAlburnus alburnusDN MW135111
P. cuticola01_2[54]MAlburnus alburnusDN MW135111
Posthodiplostomum sp.-[55]-Channa argusJP AB693170
Digenean trematodes have been documented in various parts of Europe, including neighbouring regions; however, there is limited information on the specific distribution and findings of digenean trematode species in Lithuania. Our study aimed to enhance the understanding of the epidemiology and ecology of trematode species in the Baltic region. Such research is crucial for effectively monitoring and managing wildlife health, especially aquatic bird populations that may serve as definitive hosts for these parasites. Further comprehensive parasitological surveys and molecular analyses are essential to completely understand the distribution of these trematodes in Lithuania.

5. Conclusions

Phylogenetic tree analysis of COI gene sequences revealed distinct clades for the species Australapatemon, Posthodiplostomum, and Cotylurus, with strong bootstrap support values indicating reliable relationships among them. The sequences obtained in this study align well within these clades, thereby contributing valuable data to our understanding of the phylogeny and distribution of these parasitic species. This research is the first comprehensive survey of leech parasites in Lithuania, providing important baseline data for future ecological and epidemiological studies.

Author Contributions

Conceptualisation, I.Š. and J.R.-S.; investigation, I.Š. and J.R.-S.; writing—draft preparation, I.Š., J.R.-S., L.G. and B.J.; writing—review and editing, I.Š., J.R.-S. and L.G. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Institutional Review Board Statement

Not applicable.

Data Availability Statement

All data supporting this review are available in the cited references.

Conflicts of Interest

The authors declare no conflicts of interest.

References

  1. Demshin, N.I. Sexually mature trematode Hirudineatrema oschmarini sp. gen. et subfam. nov.—A parasite of leeches. Proc. Far East. Branch. Acad. Sci. USSR 1968, 26, 41–45. (In Russian) [Google Scholar]
  2. Demshin, N.I. Oligochaetes and Leeches as Intermediate Hosts of Helminths; Publishing House «Nauka», Siberian Branch: Novosibirsk, Russia, 1975; Volume 192. (In Russian) [Google Scholar]
  3. Vusse, F.J.V.; Fish, T.D.; Neumann, M.P. Adult digenea from upper midwest hirudinid leeches. J. Parasitol. 1981, 67, 717–720. [Google Scholar] [CrossRef]
  4. Tkach, V.V.; Greiman, S.E.; Steffes, K.R. Alloglossidium demshini sp. nov. (Digenea: Macroderoididae) from leeches in Minnesota. Acta Parasitol. 2013, 58, 434–440. [Google Scholar] [CrossRef]
  5. May, L. Epizoic and parasitic rotifers. Hydrobiologia 1989, 186/187, 59–67. [Google Scholar] [CrossRef]
  6. Koste, W.; Shiel, R.J. Rotifera from Australian inland waters VII. Notommatidae (Rotifera: Monogononta). Trans. R. Soc. S. Aust. 1991, 115, 111–159. [Google Scholar]
  7. Wise, M.R.; Janovy, J.J.; Wise, J.C. Host specificity in Metamera sillasenorum, n. sp., a gregarine parasite of the leech Helobdella triserialis with notes on transmission dynamics. J. Parasitol. 2000, 86, 602–606. [Google Scholar] [CrossRef] [PubMed]
  8. Kikuchi, Y.; Fukatsu, T. Rickettsia Infection in Natural Leech Populations. Microb. Ecol. 2005, 49, 265–271. [Google Scholar] [CrossRef]
  9. Pospekhovaa, N.A.; Regel, K.V. Ultrastructure of the metacestode Aploparaksis shigini Bondarenko et Kontrimavichius, 2006 (Cestoda: Aploparakside). Parasitology 2021, 55, 73–80. [Google Scholar]
  10. Pyrka, E.; Kanarek, G.; Zaleśny, G.; Hildebrand, J. Leeches as the intermediate host for strigeid trematodes: Genetic diversity and taxonomy of the genera Australapatemon Sudarikov, 1959 and Cotylurus Szidat, 1928. Parasites Vectors 2021, 14, 44. [Google Scholar] [CrossRef]
  11. Timm, T. Eesti Rõngusside (Annelida) Määraja: A Guide to the Estonian Annelida; Eesti Looduseuurijate Selts, Teaduste Akadeemia Kirjastus: Tartu, Estonia, 1999; Volume 208. [Google Scholar]
  12. Bielecki, A.; Cichocka, M.J.; Jeleń, I.; Świątek, P.; Adamiak-Brud, Ż. A checklist of leech species from Poland. Wiad. Parazytol. 2011, 57, 11–20. [Google Scholar] [PubMed]
  13. Eguileor, M.; Grimaldi, A.; Tettamanti, G.; Congiu, T.; Protasoni, M.; Reguzzoni, M.; Valvassori, R.; Lanzavecchia, G. Ultrastructure and functional versatility of hirudinean botryoidal tissue. Tissue Cell 2001, 33, 332–341. [Google Scholar] [CrossRef]
  14. Margolis, L.; Esch, G.W.; Holmes, J.C.; Kuris, A.M.; Schad, G.A. The Use of Ecological Terms in Parasitology (Report of an Ad Hoc Committee of the American Society of Parasitologists). J. Parasitol. 1992, 1, 131–133. [Google Scholar] [CrossRef]
  15. Bush, A.O.; Lafferty, K.D.; Lotz, J.M.; Shostak, A.W. Parasitology meets ecology on its own terms: Margolis et al. J. Parasitol. 1997, 83, 575–583. [Google Scholar] [CrossRef] [PubMed]
  16. Rozsa, L.; Reiczigel, J.; Majoros, G. Quantifying parasites in samples of hosts. J. Parasitol. 2000, 86, 228–232. [Google Scholar] [CrossRef]
  17. Munn, Z.; Moola, S.; Lisy, K.; Riitano, D.; Tufanaru, C. Chapter 5: Systematic reviews of prevalence and incidence. In JBI Manual for Evidence Synthesis; Aromataris, E., Munn, Z., Eds.; JBI: Adelaide, Australia, 2020. [Google Scholar]
  18. Thompson, J.D.; Higgins, D.G.; Gibson, T.J. Clustal W: Improving the sensitivity of progressive multiple sequence alignment through sequence weighting, position-specific gap penalties and weight matrix choice. Nucleic Acids Res. 1994, 22, 4673–4680. [Google Scholar] [CrossRef] [PubMed]
  19. Kumar, S.; Stecher, G.; Li, M.; Knyaz, C.; Tamura, K. MEGA X: Molecular Evolutionary Genetics Analysis across Computing Platforms. Mol. Biol. Evol. 2018, 35, 1547–1549. [Google Scholar] [CrossRef]
  20. Felsenstein, J. Evolutionary trees from DNA sequences: A maximum likelihood approach. J. Mol. Evol. 1981, 17, 368–376. [Google Scholar] [CrossRef]
  21. Darriba, D.; Taboada, G.L.; Doallo, R.; Posada, D. jModelTest 2: More models, new heuristics and parallel computing. Nat. Methods 2012, 9, 772. [Google Scholar] [CrossRef] [PubMed]
  22. Pyrka, E.; Kanarek, G.; Gabrysiak, J.; Jezewski, W.; Cichy, A.; Stanicka, A.; Zbikowska, E.; Zalesny, G.; Hildebrand, J. Life history strategies of Cotylurus spp. Szidat, 1928 (Trematoda, Strigeidae) in the molecular era—Evoluti onary consequences and implications for taxonomy. Int. J. Parasitol. Parasites Wildl. 2022, 18, 201–211. [Google Scholar] [CrossRef]
  23. Spelling, S.M.; Young, J.O. Seasonal Occurrence of Metacercariae of the Trematode Cotylurus cornutus (Szidat) in Three Species of Lake-Dwelling Leeches. J. Parasitol. 1986, 72, 837–845. [Google Scholar] [CrossRef]
  24. Jones, A.; Bray, R.A.; Gibson, D.I. Book Keys to the Trematoda; CABI Publishing: London, UK, 2005; Volume 2, p. 768. [Google Scholar]
  25. Davies, D.; Ostrowski de Núñez, M. The life cycle of Australapatemon magnacetabulum (Digenea: Strigeidae) from northwestern Argentina. J. Parasitol. 2012, 98, 778–783. [Google Scholar] [CrossRef]
  26. Faltýnková, A.; Nasincová, V.; Kablásková, L. Larval trematodes (Digenea) of the great pond snail, Lymnaea stagnalis (L.), (Gastropoda, Pulmonata) in Central Europe: A survey of species and key to their identification. Parasite 2007, 14, 39–51. [Google Scholar] [CrossRef]
  27. Karvonen, A.; Faltýnková, A.; Choo, J.M.; Valtonen, E.T. Infection, specifity and host manipulation of Australapatemon sp. (Trematoda, Strigeidae) in two sympatric species of leeches (Hirudinea). Parasitology 2017, 144, 1346–1355. [Google Scholar] [CrossRef]
  28. Calhoun, D.M.; Esfahani, E.; Locke, S.A.; Moser, W.E.; Johnson, P.T.J. How parasite exposure and time interact to determine Australapatemon burti (Trematoda: Digenea) infections in second intermediate hosts (Erpobdella microstoma) (Hirudinea: Erpodellidae). Exp. Parasitol. 2020, 219, 108002. [Google Scholar] [CrossRef] [PubMed]
  29. Blasco-Costa, I.; Poulin, R.; Presswell, B. Species of Apatemon Szidat, 1928 and Australapatemon Sudarikov, 1959 (Trematoda: Strigeidae) from New Zealand: Linking and characterising life cycle stages with morphology and molecules. Parasitol. Res. 2016, 115, 271–289. [Google Scholar] [CrossRef] [PubMed]
  30. Niewiadomska, K. Family Strigeidae Railliet Keys to the Trematoda; Gibson, D.I., Jones, A., Bray, R.A., Eds.; CABI Publishing and the Natural History Museum: Wallingford, UK, 2002; pp. 231–241. [Google Scholar]
  31. Gordy, M.A.; Locke, S.A.; Rawlings, T.A.; Lapierre, A.R.; Hanington, P.C. Molecular and morphological evidence for nine species in North American Australapatemon (Sudarikov, 1959): A phylogeny expansion with description of the zygocercous Australapatemon mclaughlini n. sp. Exp. Parasitol. 2020, 219, 108002. [Google Scholar] [CrossRef]
  32. Zrnčić, S.; Oraić, D.; Mihaljević, Ž.; Ćaleta, M.; Zanella, D.; Jelić, D.; Jelić, M. First observation of Posthodiplostomum cuticola (Nordmann, 1832) metacercariae in cypriniformes from Croatia. Helminthologia 2009, 46, 112–116. [Google Scholar] [CrossRef]
  33. Mierzerjewska, K.; Wlasw, T.; Kapusta, A.; Szynanccyk, K. Fish digeneans from the seven islands ornithological reserve at Oswin lake Poland. Part I. Posthodiplostomum cuticola von Nordmann, 1832. Acta Ichthyol. Piscat. 2004, 34, 73–84. [Google Scholar]
  34. Ondračkova, M.; Bartosova, S.; Valova, Z.; Jurajda, P.; Gelnar, M. Occurrence of black-spot disease caused by metacercariae of Posthodiplostomum cuticola among juvenile fishes in water bodies in the Morava River basin. Acta Parasitol. 2004, 49, 222–227. [Google Scholar]
  35. Cech, G.; Sándor, D.; Molnár, K.; Paulus, P.; Papp, M.; Preiszner, B.; Vitál, Z.; Varga, Á.; Székely, C. New record of metacercariae of the North American Posthodiplostomum centrarchi (Digenea, Diplostomidae) in pumpkinseed (Lepomis gibbosus) in Hungary. Acta Vet. Hung. 2020, 68, 20–29. [Google Scholar] [CrossRef]
  36. Sawyer, R.T. Book Leech Biology and Behaviour; Clarendon Press: Oxford, UK; Oxford University Press: New York, NY, USA; Volume 1.
  37. Van Haaren, T.; Hop, H.; Soes, M.; Tempelman, D. The freshwater leeches (Hirudinea) of The Netherlands. Lauterbornia 2004, 52, 113–131. [Google Scholar]
  38. Tiberti, R.; Gentill, A. First report of freshwater leech Helobdella stagnalis (Rhyncobdellida:Glossiphoniidae) as a parasite of an anuran amphibian. Acta Herpetol. 2010, 5, 255–258. [Google Scholar]
  39. Faltýnková, A.; Sures, B.; Kostadinova, A. Biodiversity of trematodes in their intermediate mollusc and fish hosts in the freshwater ecosystems of Europe. Syst Parasitol. 2016, 93, 283–293. [Google Scholar] [CrossRef]
  40. Molloy, D.P.; Karatayev, A.Y.; Burlakova, L.E.; Kurandina, D.P.; Laruelle, F. Natural enemies of zebra mussels: Predators, parasites, and ecological competitors. Reviews in Fisheries Science 1997, 5, 27–97. [Google Scholar] [CrossRef]
  41. Palmieri, J.R.; James, H.A. The effects of leech behavior on penetration and localization of Apatemon gracilis (Trematoda: Strigeidae) cercariae and metacercariae. Great Basin Nat. 1976, 36, 97–100. [Google Scholar]
  42. Nakao, M.; Sasaki, M. Trematode diversity in freshwater snails from a stopover point for migratory waterfowls in Hokkaido, Japan: An assessment by molecular phylogenetic and population genetic analyses. Parasitol. Int. 2021, 83, 102329. [Google Scholar] [CrossRef] [PubMed]
  43. Locke, S.A.; Van Dam, A.; Caffara, M.; Pinto, H.A.; López-Hernández, D.; Blanar, C.A. Validity of the Diplostomoidea and Diplostomida (Digenea, Platyhelminthes) upheld in phylogenomic analysis. Int. J. Parasitol. 2018, 48, 1043–1059. [Google Scholar] [CrossRef] [PubMed]
  44. Achatz, T.J.; Chermak, T.P.; Martens, J.R.; Pulis, E.E.; Fecchio, A.; Bell, J.A.; Greiman, S.E.; Cromwell, K.J.; Brant, S.V.; Kent, M.L.; et al. Unravelling the diversity of the Crassiphialinae (Digenea: Diplostomidae) with molecular phylogeny and descriptions of five new species. Curr. Res. Parasitol. Vector-Borne Dis. 2021, 1, 100051. [Google Scholar] [CrossRef]
  45. Hernández-Mena, D.I.; García-Varela, M.; Pérez-Ponce de León, G. Filling the gaps in the classification of the Digenea Carus, 1863: Systematic position of the Proterodiplostomidae Dubois, 1936 within the superfamily Diplostomoidea Poirier, 1886, inferred from nuclear and mitochondrial DNA sequences. Syst. Parasitol. 2017, 94, 833–848. [Google Scholar] [CrossRef]
  46. Stoyanov, B.; Georgieva, S.; Pankov, P.; Kudlai, O.; Kostadinova, A.; Georgiev, B.B. Morphology and molecules reveal the alien Posthodiplostomum centrarchi Hoffman, 1958 as the third species of Posthodiplostomum Dubois, 1936 (Digenea: Diplostomidae) in Europe. Syst. Parasitol. 2017, 94, 1–20. [Google Scholar] [CrossRef] [PubMed]
  47. Koxlien, B.; Rottier, L.; Choudhury, A. Posthodiplostomum centrarchi metacercaria (GenBank Accession No. X0891). Unpublished GenBank submission. 2022.
  48. Koxlien, B.; Rottier, L.; Choudhury, A. Posthodiplostomum cf. anterovarium metacercaria (GenBank Accession No. X0893). Unpublished GenBank submission. 2022. [Google Scholar]
  49. Svinin, A.O.; Chikhlyaev, I.V.; Bashinskiy, I.W.; Osipov, V.V.; Neymark, L.A.; Ivanov, A.Y.; Stoyko, T.G.; Chernigova, P.I.; Ibrogimova, P.K.; Litvinchuk, S.N.; et al. Diversity of trematodes from the amphibian anomaly P hotspot: Role of planorbid snails. PLoS ONE 2023, 18, e0281740. [Google Scholar] [CrossRef]
  50. Kanarek, G.; Gabrysiak, J.; Pyrka, E.; Jezewski, W.; Stadnicka, A.; Cichy, A.; Zbikowska, E.; Zalesny, G.; Hildebrand, J. Hyperparasitism among larval stages of Digenea in snail hosts: Sophisticated life strategy or pure randomness? The scenario of Cotylurus sp. Zool. J. Linn. Soc. 2023, 4, 865–875. [Google Scholar]
  51. Pérez-Ponce de León, G.; Sereno-Uribe, A.L.; Pinacho-Pinacho, C.D.; García-Varela, M. Assessing the genetic diversityof the metacercariae of Posthodiplostomum minimum (Trematoda: Diplostomidae) in Middle American freshwater fishes: One species or more? Parasitology 2022, 149, 239–252. [Google Scholar] [CrossRef]
  52. Heneberg, P.; Sitko, J.; Telšinski, M. Paraphyly of Conodiplostomum Dubois, 1937. Parasitol. Int. 2020, 76, 102033. [Google Scholar] [CrossRef]
  53. Duan, Y.; Al-Jubury, A.; Kania, P.W.; Buchmann, K. Trematode diversity reflecting the community structure of Danish freshwater systems: Molecular clues. Parasites Vectors 2021, 14, 43. [Google Scholar] [CrossRef] [PubMed]
  54. Duan, Y.; Buchmann, K.; Kania, P.W. Aquatic Pathobiology. University of Copenhagen: Stigbojlen 7, Frederiksberg, Denmark, 2020; submitted. [Google Scholar]
  55. Nguyen, T.C.; Li, Y.C.; Makouloutou, P.; Jimenez, L.A.; Sato, H. Posthodiplostomum sp. Metacercariae in the trunk muscle of northern snakeheads (Channa argus) from the Fushinogawa River, Yamaguchi, Japan. J. Vet. Med. Sci. 2012, 74, 1367–1372. [Google Scholar]
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Figure 1. Phylogenetic tree of 28S rRNA gene sequences of the genera Cotylurus and Phosthodiplostomum constructed using the maximum likelihood method and the Kimura 2 model. Bootstrap values representing the phylogenetic relationships are shown above the branches, based on 1000 replications. The analysed sequences obtained during this study are marked (■). Icons next to the sequence names represent the host species. Abbreviations: LT—Lithuania; PL—Poland; JP—Japan; CA—Canada; UA—Ukraine; MX—Mexico; CZ—Czech Republic; USA—United States of America.
Figure 1. Phylogenetic tree of 28S rRNA gene sequences of the genera Cotylurus and Phosthodiplostomum constructed using the maximum likelihood method and the Kimura 2 model. Bootstrap values representing the phylogenetic relationships are shown above the branches, based on 1000 replications. The analysed sequences obtained during this study are marked (■). Icons next to the sequence names represent the host species. Abbreviations: LT—Lithuania; PL—Poland; JP—Japan; CA—Canada; UA—Ukraine; MX—Mexico; CZ—Czech Republic; USA—United States of America.
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Figure 2. Phylogenetic tree of the COI gene sequences of the genera Cotylurus, Australapatemon, and Phosthodiplostomum constructed using the maximum likelihood method and the Kimura 2 model. Bootstrap values representing the phylogenetic relationships are shown above the branches, based on 1000 replications. The analysed sequences obtained during this study are marked (■). Icons next to the sequence names represent the host species. Abbreviations: LT—Lithuania; PL—Poland; JP—Japan; CA—Canada; CZ—Czech Republic; CR—Costa Rica; RU—Russia.
Figure 2. Phylogenetic tree of the COI gene sequences of the genera Cotylurus, Australapatemon, and Phosthodiplostomum constructed using the maximum likelihood method and the Kimura 2 model. Bootstrap values representing the phylogenetic relationships are shown above the branches, based on 1000 replications. The analysed sequences obtained during this study are marked (■). Icons next to the sequence names represent the host species. Abbreviations: LT—Lithuania; PL—Poland; JP—Japan; CA—Canada; CZ—Czech Republic; CR—Costa Rica; RU—Russia.
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Figure 3. Phylogenetic tree of sequences of the ITS2 region of the genus Phosthodiplostomum constructed using the maximum likelihood method and the Kimura 2 model. Bootstrap values representing the phylogenetic relationships are shown above the branches, based on 1000 replications. The analysed sequences obtained during this study are marked (■). Icons next to the sequence names represent the host species. Abbreviations: LT—Lithuania; HU—Hungary; DK—Denmark; JP—Japan.
Figure 3. Phylogenetic tree of sequences of the ITS2 region of the genus Phosthodiplostomum constructed using the maximum likelihood method and the Kimura 2 model. Bootstrap values representing the phylogenetic relationships are shown above the branches, based on 1000 replications. The analysed sequences obtained during this study are marked (■). Icons next to the sequence names represent the host species. Abbreviations: LT—Lithuania; HU—Hungary; DK—Denmark; JP—Japan.
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Table 1. Parasitological parameters of leeches infection in three water bodies in Lithuania, in 2022–2024 (Abbreviations: AH—Alboglossiphonia heteroclita; GC—Glossiphonia complanata; GV—Glossiphonia verrucata; HM—Hemiclepsis marginata; HSt—Helobdella stagnalis; TT—Teromyzon tessulatum; EO—Erpobdella octoculata; HS—Haemopis sanguisuga; C—Cotylurus; A—Australapatemon; P—Posthodiplostomum).
Table 1. Parasitological parameters of leeches infection in three water bodies in Lithuania, in 2022–2024 (Abbreviations: AH—Alboglossiphonia heteroclita; GC—Glossiphonia complanata; GV—Glossiphonia verrucata; HM—Hemiclepsis marginata; HSt—Helobdella stagnalis; TT—Teromyzon tessulatum; EO—Erpobdella octoculata; HS—Haemopis sanguisuga; C—Cotylurus; A—Australapatemon; P—Posthodiplostomum).
Waterbody,
Locality, and Coordinates 		Leech SpeciesNumber of Dissected/Number of Infected LeechesMetacercariae
Prevalence %		Intensity of Infection
(Average) (Min–Max)		Genus of Trematodes/
Co-Infection
Maišia, Kaunas,
54°82′94.58″ N, 23°87′94.04″ E		AH 15/0-
GC67/3146.312.6 (1–70) C(21), P(1), C/A(6), P/C(3)
HM4/0---
HSt237/7832.95.7 (1–31)C(76), C/A(1), P/C(1)
TT13/215.41.5 (1–2)-
EO256/12448.44.9 (1–30)C(122), A(1), P(1)
Total in Maišia 592/23539.76.17 (1–70)C(221), A(1), P(2), C/A(7), P/C(4)
Neris, Kaunas region,
Smiltynai,
54°95′31.30″ N, 23°98′41.23″ E		GC1/0---
TT7/0---
HS4/0---
EO18/15.51 with 1C(1)
Neris, Kaunas region
54°95′90.49″ N, 23°95′60.65″ E		HSt12/0---
EO16/16.251 with 2C(1)
Total in Neris 58/23.441–2; 1.5C(2)
Nemunas I site
54°98′96.24″ N, 23°59′53.70″ E
(swampy)		GC12/975.01.5 (1–2)C(2)
GV4/375.029.2 (10–112) C(4), A/C(4), C/A/P(1)
HM8/450.046.2 (45–52) C(1), A(1), C/A/P(1)
HSt19/947.344.0 (3–5)C(4)
TT7/218.29.1 (2–22)C(6), A/C(3)
EO27/1451.81.5 (1–2)A(2)
Nemunas II site
54°98′89.00″ N, 23°59′60.74″ E
(clear flowing)		AH4/375.02.7 (2–3) C (3)
GC9/777.812.5 (12–13) C(4), A(1), A/C(2)
HM1/0---
HSt10/770.09.7 (3–23) C(6), A/C(1)
EO11/111006.7 (1–67)C(11)
Nemunas III site
54°89′27.09″ N, 23°89′78.72″ E		GC1/11001 with 18C(1)
EO8/81005.8 (1–13) C(7), A(1)
Total in Nemunas 121/7864.510.0 (21–112) C(56), A(10), A/C (11), P/C(1), C/A/P(2)
Total in all sites 771/31540.85.89 (1–112)C(279), A(11), A/C(18), P/C(5), C/A/P(2), P(2)
Table 2. Total parasitological parameters in leech species across water bodies.
Table 2. Total parasitological parameters in leech species across water bodies.
Leech SpeciesNumber of Dissected/Number of Infected LeechesMetacercariae
Prevalence %		Intensity of Infection
(Min–Max; Average)		Genus of Trematodes/
Co-Infection
Alboglossiphonia heteroclita19/315.82.7 (2–3)C(3)
Glossiphonia complanata90/4853.315.5 (1–112) C(30), A(1), P(1), A/C(12), P/C(3), C/A/P(1)
Glossiphonia verrucata4/375.046.2 (45–52) C(1), A(1), C/A/P(1)
Hemiclepsis marginata13/430.73.7 (3–5)C(4)
Helobdella stagnalis278/9433.86.9 (1–31)C(88), A/C(5), P/C(1)
Teromyzon tessulatum27/414.81.5 (1–2)C(2), A(2)
Erpobdella octoculata320/15949.45.4 (1–67)C(151), A(5), P(1), A/C(1), P/C(1)
Haemopis sanguisuga4/0
Table 3. Primers used in the present study.
Table 3. Primers used in the present study.
PrimerSequenceGene
digl25′-AAGCATATCACTAAGCGG-3′28s
1500R5′-GCTATCCTGAGGGAAACTTCG-3′
BD15′-GTCGTAACAAGGTTTCCGTA-3′ITS1-5.8SrDNA-ITS2
BD25′-TATGCTTAAATTCAGCGGGT-3′
NLF5′-TTTGyACACACCGCCCGTCG-3′
NLR5′-ATATGCTTAArTTCAGCGGGT-3′
JB35′-TTTTTTGGGCATCCTGAGGTTTAT-3′COI
JB135′-TCATGAAAACACCTTAATACC-3′
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Rutkauskaitė-Sucilienė, J.; Griciuvienė, L.; Jakštys, B.; Šatkauskienė, I. Trematode Parasite Infections in Freshwater Leeches from the Central Region of Lithuania: First Record of Posthodiplostomum (Dubois, 1936) in a Leech Host. Diversity 2025, 17, 117. https://doi.org/10.3390/d17020117

AMA Style

Rutkauskaitė-Sucilienė J, Griciuvienė L, Jakštys B, Šatkauskienė I. Trematode Parasite Infections in Freshwater Leeches from the Central Region of Lithuania: First Record of Posthodiplostomum (Dubois, 1936) in a Leech Host. Diversity. 2025; 17(2):117. https://doi.org/10.3390/d17020117

Chicago/Turabian Style

Rutkauskaitė-Sucilienė, Jurgita, Loreta Griciuvienė, Baltramiejus Jakštys, and Ingrida Šatkauskienė. 2025. "Trematode Parasite Infections in Freshwater Leeches from the Central Region of Lithuania: First Record of Posthodiplostomum (Dubois, 1936) in a Leech Host" Diversity 17, no. 2: 117. https://doi.org/10.3390/d17020117

APA Style

Rutkauskaitė-Sucilienė, J., Griciuvienė, L., Jakštys, B., & Šatkauskienė, I. (2025). Trematode Parasite Infections in Freshwater Leeches from the Central Region of Lithuania: First Record of Posthodiplostomum (Dubois, 1936) in a Leech Host. Diversity, 17(2), 117. https://doi.org/10.3390/d17020117

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