Hippobdelloides, Bolotov & Pešić, 2025

Genus Hippobdelloides gen. nov.

https://zoobank.org/ urn:lsid:zoobank.org:act:312639E1-5E5D-4B20-AB24-CAC3EB3D5E2A

Type species: Clepsine jaegerskioeldi Johansson, 1909 .

Diagnosis — Medium-sized leeches; one pair of eyespots on somite III; mid-body somites triannulate; dorsal surface of each annulus with large, rounded retractile tubercles, each with a rosette of pointed papillae on the apex; mouth pore apical; one pair of compact, massive salivary glands; seven pairs of very broad, extensive branched crop caeca, each with multiple small lobes; six pairs of testisacs; male and female gonopores separated by two annuli: male gonopore on XI a1/a2, female gonopore on XI/XII ( Johansson 1909; Oosthuizen and Davies 1994).

Diagnostic remarks — Phylogenetically, the new genus represents a distinct lineage, which is distant from the Placobdelloides clade, including its type species, P. multistriatus . Morphologically, it could be distinguished from Placobdelloides by a combination of the following characters: dorsum with multiple large tubercles, each having a rosette of pointed papillae on the apex (vs dorsum with multiple small papillae); one pair of compact salivary glands (vs two pairs of compact salivary glands); and extensive branched crop caeca with multiple small lobes (vs trilobed crop caeca).

Etymology — The name of the new genus is combined from two words: ‘Hippo’ (reference to its host) and ‘bdelloides’ (reference to the former generic placement of this clade in the genus Placobdelloides ).

Host — Hippopotamus, Hippopotamus amphibius Linnaeus, 1758.

Distribution — Throughout the range of its host in Sub-Saharan Africa, including Angola, Democratic Republic of Congo, Namibia, Republic of South Africa, Sudan, and Uganda ( Johansson 1909; Moore 1933; Oosthuizen and Curtis 1990; Oosthuizen 1991; Oosthuizen and Davies 1994).

Comments — Earlier DNA-based studies showed that this species always takes a separate position on phylogenetic trees and that it does not cluster with the type species of the genus Placobdelloides ( Siddall et al. 2005; Bolotov et al. 2022b; Torres-Carrera et al. 2023). It seems to be a highly specialised parasitic leech that independently evolved in close association with its host animal, hippopotamus.

Discussion

The two new monotypic genera of the Glossiphoniidae , described above, are shown to be basally derived (see Figure 1 View Figure 1 for detail). This pattern may indicate that these leeches have only distant relation to other genus-level clades in the family and represent relict and/or highly specialised lineages (cf. Tomoyasu et al. 2025).

In particular, Eurobdelloides represents the first glossiphoniid genus endemic to Europe ( Nesemann and Neubert 1999). Examples of European endemic genera in other Hirudinea families are also not common. The family Piscicolidae contains three such genera: Caspiobdella Epshtein, 1966 , Italobdella Bielecki, 1993 , and Pawlowskiella Bielecki, 1997 ( Cichocka et al. 2023). These genera are thought to be relict clades, the origin of which is probably associated with waters derived from the ancient Tethys Sea ( Epshtein 2004). However, the lack of DNA sequences for representatives of Italobdella and Pawlowskiella precludes any final solution on the biogeographic affinities of these taxa. The family Erpobdellidae also comprises of three European endemic genera: Archaeobdella Grimm, 1876 (Caspian and Azov seas), Croatobranchus Kerovec, Kucinic & Jalzic, 1999 ( Croatia), and Fadejewobdella Lukin, 1962 (Southern European Russia and Ukraine) ( Lukin 1976; Sket et al. 2001). These genera are monotypic. Croatobranchus is a highly specialised, troglomorphic leech from deep caves of the Northern Velebit Mountains ( Sket et al. 2001). Archaeobdella is a representative of the Caspian fauna and may be considered a relict lineage, the origin of which is similar to that of the Tethysderived piscicolid genera, mentioned above ( Epshtein 2004). Fadejewobdella may represent a thermophilic relict lineage ( Lukin 1976) that probably originated in the Azov Sea refugium (cf. Tomilova et al. 2020; Marin and Palatov 2023). In turn, the land leech genus Xerobdella Frauenfeld, 1868 ( Xerobdellidae ) is endemic to Southern Europe, being distributed in the Balkans (Dinaric Alps) and Alps ( Brigić et al. 2022). This genus could be considered a relict clade that evolved in European mountain refugia ( Kutschera et al. 2007). At first glance, we could assume that Eurobdelloides also originated in a Southern European refugium (e.g., the Balkans; cf. Lyubas et al. 2022) with a subsequent (postglacial) colonisation of more northern areas in Eastern Europe. The presence of the vector tissue in Eurobdelloides may be regarded a plesiomorphic feature, because it occurs in phylogenetically old lineages such as representatives of the family Acanthobdellidae ( Bielecki 2004) . The genus Hyperboreomyzon could be evaluated as another example of a relict monotypic genus-level lineage that originated in mountain refugia of Central Asia (Altai Mountains) and colonised the Arctic later on ( Eliseeva et al. 2024).

In contrast, Hippobdelloides seems to be a highly specialised lineage that derived based on a long-term coevolution with its host ( Oosthuizen and Davies 1994). Paleontological records reveal that the earliest representatives of the family Hippopotamidae appeared in the Early Miocene of East Africa ( Tsubamoto et al. 2015). The active colonisation and increased ecological impact of the Hippopotaminae into wet habitats throughout Africa and Eurasia occurred at approximately 8 Ma (the so-called Hippopotamine Event; Boisserie and Bibi 2022). Based on this indirect evidence, we could assume that the association of Hippobdelloides with its host evolved since the mid-Miocene or even earlier. Marsupiobdella africana may represent an additional example of such host-derived, deeply divergent genus-level lineage. This species has a complex life cycle and uses the frog Xenopus laevis (Daudin, 1802) as the primary host and the freshwater crab Potamonautes perlatus (H. Milne Edwards, 1837) as shelter/hard substrate ( Badets and Du Preez 2014; Kruger and Du Preez 2015).

Perhaps, Maiabdella batracophila Ringuelet, 1980 may be regarded as a younger example of such highly specialised lineage, having a narrow host range ( Telmatobius frogs) and dwelling in high elevation habitats of the High Andes ( Ringuelet 1980; Canazas-Teran et al. 2024). Although this taxon represents a paraphyletic subclade in the Helobdella clade ( Torres-Carrera et al. 2023), it could be evaluated as an example when morphological and ecological specialisation at extreme environments goes faster than phylogenetic distinctiveness (see Turner 2024 for the theoretical basis of this assumption). Similar cases could be seen in Baicaloclepsis Lukin & Epstein, 1959 and Paratorix Lukin & Epstein, 1960 , containing morphologically highly specialised leeches that are adapted to live in open waters of Lake Baikal ( Lukin 1976). Phylogenetically, these leech genera fall within the Glossiphonia clade and were considered synonyms of the latter genus ( Siddall et al. 2005; Bolotov et al. 2023).

Acknowledgements

We are grateful to the Associate Editor Djuradj Milošević, as well as to Clemens Grosser and one anonymous reviewer for valuable comments on earlier versions of this paper. This study was supported by the Ministry of Science and Higher Education of Russia (project No. FUUW-2025-0022).

References

Apakupakul, K., Siddall, M. E. & Burreson, E. M. (1999) Higher level relationships of leeches (Annelida: Clitellata: Euhirudinea) based on morphology and gene sequences. Molecular Phylogenetics and Evolution, 12 (3), 350–359. https://doi.org/10.1006/mpev.1999.0639

Badets, M. & Du Preez, L. (2014) Phoretic interaction between the kangaroo leech Marsupiobdella africana (Hirudinea: Glossiphoniidae) and the cape river crab Potamonautes perlatus (Decapoda: Potamonautidae). International Journal for Parasitology: Parasites and Wildlife, 3 (1), 6–11. https://doi.org/10.1016/j.ijppaw.2013.10.001

Bielecki, A. (2004) Description of a vector tissue in Batracobdelloides moogi Nesemann and Csányi 1995 (Hirudinea: Glossiphoniidae Vaillant, 1850). Lauterbornia, 52, 101–106.

Bielecki, A., Cichocka, J. M., Jeleń, I., Ropelewska, E., Adamiak- Brud, Ż., Biedunkiewicz, A. & Dziekońska- Rynko, J. (2011) Batracobdelloides moogi Nesemann et Csányi, 1995 (Hirudinida: Glossiphoniidae): Morphometry and structure of the alimentary tract and reproductive system. Biologia, 66, 848–855. https://doi.org/10.2478/s11756-011-0100-8

Bielecki, A., Daczewska, M. & Jarosz, A. (2000) Parasites leech Batracobdelloides moogi (Nesemann & Csanyi, 1995) (Hirudinea, Glossiphoniidae Vaillant, 1850) of Polish fauna? Wiadomosci Parazytologiczne, 46 (1), 101–104. [in Polish]

Boisserie, J. R. & Bibi, F. (2022) 15. Hippopotamidae from the Baynunah Formation. In: Bibi, F., Kraatz, B., Beech, M.J. & Hill, A. (eds) Sands of Time: Ancient life in the late Miocene of Abu Dhabi, United Arab Emirates. Springer International Publishing, Cham, pp. 243–260.

https://doi.org/10.1007/978-3-030-83883-6_15

Bolotov, I. N., Kondakov, A. V., Eliseeva, T. A., Aksenova, O. V., Babushkin, E. S., Bespalaya, Y. V., Chertoprud, E. S., Dvoryankin, G. A., Gofarov, M. Y., Klass, A. L., Konopleva, E. S., Kropotin, A. V., Lyubas, A. A., Makhrov, A. A., Palatov, D. M., Shevchenko, A. R., Sokolova, S. E., Spitsyn, V. M., Tomilova, A. A., Vikhrev, I. V., Zubrii, N. A. & Vinarski, M. V. (2022 a) Cryptic taxonomic diversity and high-latitude melanism in the glossiphoniid leech assemblage from the Eurasian Arctic. Scientific Reports, 12, 20630. https://doi.org/10.1038/s41598-022-24989-7

Bolotov, I. N., Eliseeva, T. A. & Kondakov, A. V. (2022 b) A new freshwater leech genus from Southeast Asia (Hirudinea: Glossiphoniidae). Ecologica Montenegrina, 56, 1–9.

https://doi.org/10.37828/em.2022.56.1

Bolotov, I. N., Eliseeva, T. A., Kondakov, A. V., Konopleva, E. S., Palatov, D. M., Sokolova, A. M., Vikhrev, I.V., Gofarov, M.Y., Bovykina, G.V., Nyein Chan, Zau Lunn & Than Win (2022 c) Hidden shelter-like associations of minute Alboglossiphonia leeches (Hirudinea: Glossiphoniidae) with sedentary animals and molluscs. Limnologica, 97, 126028.

https://doi.org/10.1016/j.limno.2022.126028

Bolotov, I. N., Eliseeva, T. A., Kondakov, A. V., Kropotin, A. V., Aksenova, O. V., Bespalaya, Y. V., Travina, O. V., Gofarov, M. Y., Kim, S. K., Lee, J. H. & Vinarski, M. V. (2023) Taxonomy and Melanism Patterns of Freshwater Leeches in the Genus Glossiphonia (Hirudinea: Glossiphoniidae) from Northeast Asia. Diversity, 15 (6), 756.

https://doi.org/10.3390/d15060756

Bolotov, I. N., Klass, A. L., Kondakov, A. V., Vikhrev, I. V., Bespalaya, Y. V., Gofarov, M. Y., Filippov, B.Y., Bogan, A. E., Lopes-Lima, M., Zau Lunn, Nyein Chan, Aksenova, O. V., Dvoryankin, G. A., Chapurina, Y. E., Kim, S. K., Kolosova, Y. S., Konopleva, E. S., Lee, J. H., Makhrov, A. A., Palatov, D. M., Sayenko, E. M., Spitsyn, V. M., Sokolova, S. E., Tomilova, A. A., Than Win, Zubrii, N. A. & Vinarski, M. V. (2019) Freshwater mussels house a diverse mussel-associated leech assemblage. Scientific Reports, 9, 16449.

https://doi.org/10.1038/s41598-019-52688-3

Bolotov, I. N., Klass, A. L., Konopleva, E. S., Bespalaya, Y. V., Gofarov, M. Y., Kondakov, A. V. & Vikhrev, I. V. (2020) First freshwater mussel-associated piscicolid leech from East Asia. Scientific Reports, 10, 19854. https://doi.org/10.1038/s41598-020-76854-0

Bolotov, I. N., Eliseeva, T. A., Bespyatykh, A. V., Kuznetsova, E. Y. & Kondakov, A. V. (2025) Rediscovered historical lots uncover the identity of Nikolaj A. Livanow’s Protoclepsis species and clarify the taxonomy of Palearctic waterfowl-associated leeches (Hirudinea: Glossiphoniidae). Systematic Parasitology. https://doi.org/10.1007/s11230-025-10221-3

Borda, E. & Siddall, M. E. (2004 a) Review of the evolution of life history strategies and phylogeny of the Hirudinida (Annelida: Oligochaeta). Lauterbornia, 52, 5–25.

Borda, E. & Siddall, M. E. (2004 b) Arhynchobdellida (Annelida: Oligochaeta: Hirudinida): phylogenetic relationships and evolution. Molecular Phylogenetics and Evolution, 30 (1), 213– 225. https://doi.org/10.1016/j.ympev.2003.09.002

Brigić, A., Medak, K., Rebrina, F., Jelić, M., Alegro, A. & Kerovec, M. (2022) Ecology and Biology of the Rare Endemic Land Leech Xerobdella anulata (Xerobdellidae). Diversity, 14 (9), 701.

https://doi.org/10.3390/d14090701

Canazas-Teran, A., Meza, G., Mestas-Valdivia, B., Morales, A., Oceguera-Figueroa, A., Catenazzi, A., Von May, R. & Santa-Cruz, R. (2024) Leeches (Hirudinea: Glossiphoniidae: Maiabdella batracophila and Helobdella sp.) associated with Andean water frogs (Anura: Telmatobiidae: Telmatobius) in southern Peru. Salamandra, 60, 94–103.

Castresana, J. (2000) Selection of conserved blocks from multiple alignments for their use in phylogenetic analysis. Molecular Biology and Evolution, 17, 540–552.

https://doi.org/10.1093/oxfordjournals.molbev.a026334

Chernomor, O., von Haeseler, A. & Minh, B. Q. (2016) Terrace aware data structure for phylogenomic inference from supermatrices. Systematic Biology, 65, 997–1008.

https://doi.org/10.1093/sysbio/syw037

Chiangkul, K., Trivalairat, P., Kunya, K. & Purivirojkul, W. (2021 a) Placobdelloides tridens sp. n., a new species of glossiphoniid leech (Hirudinea: Rhynchobdellida) found feeding on captive Orlitia borneensis in Thailand, and an update to the host distribution of P. siamensis. Systematic Parasitology, 98 (2), 141–154. https://doi.org/10.1007/s11230-021-09967-3

Chiangkul, K., Trivalairat, P. & Purivirojkul, W. (2021 b) Batracobdelloides bangkhenensis sp. n. (Hirudinea: Rhynchobdellida), a new leech species parasite on freshwater snails from Thailand. Parasitology Research, 120, 93–107. https://doi.org/10.1007/s00436-020-06919-6

Cichocka, J. M., Košel, V., Świątek, P., Hildebrand, J., Gajda, Ł., Lecaplain, B., Nieoczym, M. & Bielecki, A. (2023) Italobdella bieleckii sp. n. (Hirudinea: Piscicolidae), a new leech species from the Danube in Slovakia. Biologia, 78 (9), 2449–2461. https://doi.org/10.1007/s11756-023- 01377-8

Csabai, Z., Boda, P., Boda, R., Bódis, E., Danyik, T., Deák, C., Farkas, A., Kálmán, Z., Lőkkös, A., Málnás, K., Mauchart, P. & Móra, A. (2015) Aquatic macroinvertabrate fauna of the Kis-Sárrét nature protection area with first records of five species from Hungary. Acta biologica Debrecina. Supplementum Oecologica Hungarica, 33, 9–70.

Dereeper, A., Guignon, V., Blanc, G., Audic, S., Buffet, S., Chevenet, F., Dufayard, J.-F., Guindon, S., Lefort, V., Lescot, M., Claverie, J.-M. & Gascuel, O. (2008) Phylogeny.fr: robust phylogenetic analysis for the non-specialist. Nucleic Acids Research, 36, W465–W 469.

https://doi.org/10.1093/nar/gkn180

Eliseeva, T. A., Bolotov, I. N., Gofarov, M. Y., Bovykina, G. V., Tsiplenkina, I. G. & Kondakov, A. V. (2024) A high-altitude population of Hyperboreomyzon polaris (Hirudinea: Glossiphoniidae) in Altai Mountains, South Siberia, Russia. Systematic Parasitology, 101 (6), 66.

https://doi.org/10.1007/s11230-024-10169-w

Epshtein, V. M. (2004) On the origin of the Hirudinea fauna, especially Piscicolidae, in ancient lakes. Lauterbornia, 52, 181–193.

Grosser, C. & Pešić, V. (2005) First record of Batracobdelloides moogi (Hirudinea: Glossiphoniidae) in the Balkans. Natura Montenegrina, 4, 29–32.

Hammer, Ø., Harper, D. A. T. & Ryan, P. D. (2001) PAST: Paleontological Statistics Software Package for Education and Data Analysis. Palaeontologia Electronica, 4, 1–9.

Harding, W. A. & Moore, J. P. (1927) Hirudinea. The Fauna of British India, including Ceylon and Burma. Taylor and Francis, London, 302 pp.

Hoang, D. T., Chernomor, O., Von Haeseler, A., Minh, B. Q. & Vinh, L. S. (2018) UFBoot2: improving the ultrafast bootstrap approximation. Molecular Biology and Evolution, 35 (2), 518–522.

https://doi.org/10.1093/molbev/msx281

Johansson, L. (1909) Einige neue Arten Glossosiphoniden aus dem Sudan. Zoologischer Anzeiger, 35 (4/ 5), 146–154.

Jueg, U. & Zettler, M. L. (2022) Bemerkungen zur Egel-und Krebsegelfauna (Hirudinida und Branchiobdellida) Litauens mit einer vorläufigen Checkliste. Lauterbornia, 88, 213–238.

Juhász, P., Kiss, B., Müller, Z. & Csipkés, R. (2008) Faunistical data to Hungarian Hirudinea fauna carried out on nationwide surveys in 2006 and 2007. Folia Historico-naturalia Musei Matraensis, 32, 69–75. https://real.mtak.hu/141639

Kalyaanamoorthy, S., Minh, B. Q., Wong, T. K., Von Haeseler, A. & Jermiin, L. S. (2017) ModelFinder: fast model selection for accurate phylogenetic estimates. Nature Methods, 14 (6), 587–589.

https://doi.org/10.1038/nmeth.4285

Kambayashi, C. & Nakano, T. (2023) Lumping three nominal species into one: taxonomic revision of amphibian parasitic leeches of Torix in Far East Asia (Hirudinea: Glossiphoniidae). Invertebrate Systematics, 37 (12), 819–833. https://doi.org/10.1071/IS23042

Kambayashi, C., Kurabayashi, A. & Nakano, T. (2020) Topotype-based redescription of the leech Torix tukubana (Hirudinida: Glossiphoniiformes: Glossiphoniidae). Proceedings of the Biological Society of Washington, 133 (1), 59–71. https://doi.org/10.2988/20-00003

Klass, A. L., Sokolova, S. E., Kondakov, A. V., Bespalaya, Y. V., Gofarov, M. Y., Tomilova, A. A., Vikhrev, I. V. & Bolotov, I. N. (2018) An example of a possible leech-bryozoan association in freshwater. Zookeys, 794, 23–30. https://doi.org/10.3897/zookeys.794.28088

Koperski, P. (2010) Urban environments as habitats for rare aquatic species: The case of leeches (Euhirudinea, Clitellata) in Warsaw freshwaters. Limnologica, 40 (3), 233–240.

https://doi.org/10.1016/j.limno.2009.05.001

Kruger, N. & Du Preez, L. (2015) Reproductive strategies of the kangaroo leech, Marsupiobdella africana (Glossiphoniidae). International Journal for Parasitology: Parasites and Wildlife, 4 (1), 142–147. https://doi.org/10.1016/j.ijppaw.2015.01.005

Kutschera, U., Pfeiffer, I. & Ebermann, E. (2007) The European land leech: biology and DNA-based taxonomy of a rare species that is threatened by climate warming. Naturwissenschaften, 94, 967–974. https://doi.org/10.1007/s00114-007-0278-3

Lukin, E. I. (1976) Leeches of fresh and brackish water bodies. Fauna of the USSR, 109, 1–484. [in Russian]

Lyubas, A. A., Kondakov, A. V., Tomilova, A. A., Gofarov, M. Y., Eliseeva, T. A., Konopleva, E. S., Vikhrev, I. V., Yunitsyna, O. A., Pešić, V. & Bolotov, I. N. (2022) Taxonomic reassessment of freshwater mussels from the Western Balkans reveals an overlooked but critical refugium and defines conservation priorities. Diversity, 14 (11), 935. https://doi.org/10.3390/d14110935

Marin, I. N. & Palatov, D. M. (2023) Insights on the existence of ancient glacial refugee in the Northern Black/Azov Sea Lowland, with the description of the first stygobiotic microcrustacean species of the genus Niphargus Schiödte, 1849 from the mouth of the Don River. Diversity, 15 (5), 682.

https://doi.org/10.3390/d15050682

Marinković, N., Jovičić, K., Čanak Atlagić, J., Ilić, M., Đuknić, J., Raković, M. & Paunović, M. (2021) Prvi nalaz Batracobdelloides moogi Nesemann & Csanyi, 1995 u Srbiji. In: Voda 2021: Zbornik Radova 50 Godišnje Konferencije o Aktuelnim Problemima Korišćenja i Zaštite Voda. Srpsko Društvo za Zaštitu Voda, Zlatibor, pp. 105–108. [in Serbian]

Moore, J. P. (1933) Scientific results of the Cambridge Expedition to the East African Lakes, 1930-1.- 9. Leeches. Journal of the Linnean Society of London, Zoology, 38 (259), 297–299.

https://doi.org/10.1111/j.1096-3642.1933.tb00060.x

Nakano, T. & Lai, Y. T. (2016) First record of Poecilobdella nanjingensis (Hirudinida: Arhynchobdellida: Hirudinidae) from Taiwan and its molecular phylogenetic position within the family. Species Diversity, 21 (2), 127–134. https://doi.org/10.12782/sd.21.2.127

Nakano, T. & Nguyen, S. T. (2015) A new predatory leech from Vietnam (Hirudinida: Arhynchobdellida: Salifidae): its phylogenetic position with comments on the classification of the family. Invertebrate Systematics, 29 (5), 473–486. https://doi.org/10.1071/IS15008

Nakano, T., Eto, K., Nishikawa, K., Hossman, M. Y. & Jeratthitikul, E. (2018) Systematic revision of the Southeast Asian macrophagous leeches, with the description of two new gastrostomobdellid species (Hirudinida: Arhynchobdellida: Erpobdelliformes). Zoological Journal of the Linnean Society, 184 (1), 1–30. https://doi.org/10.1093/zoolinnean/zlx097

Nakano, T., Ramlah, Z. & Hikida, T. (2012) Phylogenetic position of gastrostomobdellid leeches (Hirudinida, Arhynchobdellida, Erpobdelliformes) and a new family for the genus Orobdella. Zoologica Scripta, 41 (2), 177–185. https://doi.org/10.1111/j.1463-6409.2011.00506.x

Nesemann, H. & Csányi, B. (1995) Description of Batracobdelloides moogi n. sp., a leech genus and species new to the European fauna with notes on the identity of Hirudo paludosa Carena, 1824 (Hirudinea: Glossiphoniidae). Lauterbornia, 21, 69–78.

Nesemann, H. & Neubert, E. (1999) Süsswasserfauna von Mitteleuropa, Bd. 6/2, Annelida: Clitellata: Branchiobdellida, Acanthobdellea, Hirudinea. Spektrum Akademischer Verlag, Heidelberg, Berlin, 178 pp.

Nguyen, L.-T., Schmidt, H. A., von Haeseler, A. & Minh, B. Q. (2015) IQ-TREE: A fast and effective stochastic algorithm for estimating maximum-likelihood phylogenies. Molecular Biology and Evolution, 32, 268–274. https://doi.org/10.1093/molbev/msu300

Oosthuizen, J. H. & Curtis, B. A. (1990) An annotated checklist of the freshwater leeches (Annelida: Hirudinea) of Namibia. Cimbebasia, 12, 99–109.

Oosthuizen, J. H. (1991) An annotated check list of the leeches (Annelida: Hirudinea) of the Kruger National Park with a key to the species. Koedoe, 34 (2), 25–38.

Oosthuizen, J. H. & Davies, R. W. (1994) The biology and adaptations of the hippopotamus leech Placobdelloides jaegerskioeldi (Glossiphoniidae) to its host. Canadian Journal of Zoology, 72 (3), 418–422. https://doi.org/10.1139/z94-058

Phillips, A. J. & Siddall, M. E. (2009) Poly-paraphyly of Hirudinidae: many lineages of medicinal leeches. BMC Evolutionary Biology, 9, 246. https://doi.org/10.1186/1471-2148-9-246

Phillips, A. J., Richardson, D. J., Hammond, C. I., Gonzalez, B. C., Lazo-Wasem, E. A. & Moser, W. E. (2025) Synonymization of Placobdella picta (Verrill, 1872) (Hirudinea: Glossiphoniidae) with descriptions of two new species revealed by molecular species delimitation. Journal of Parasitology, 111 (1), 48–63. https://doi.org/10.1645/24-89

Ringuelet, R. A. (1980) Un hirudíneo con marsupio de la región Andina de Jujuy, Argentina (Maiabdella batracophila n. g., n. sp., Glossiphoniidae). Limnobios, 2, 68–71. [in Spanish]

Ringuelet, R. A. (1985) Annulata Hirudinea. Fauna de agua dulce de la Republica Argentina, 17 (1), 1– 321. [in Spanish]

Sawyer, R. T. (1986) Leech Biology and Behaviour. Vol. 2. Feeding Biology, Ecology, and Systematics. Clarendon Press, Oxford, pp. 419–793.

Siddall, M. E. & Borda, E. (2003) Phylogeny and revision of the leech genus Helobdella (Glossiphoniidae) based on mitochondrial gene sequences and morphological data and a special consideration of the triserialis complex. Zoologica Scripta, 32 (1), 23–33.

https://doi.org/10.1046/j.1463-6409.2003.00098.x

Siddall, M. E. & Burreson, E. M. (1998) Phylogeny of Leeches (Hirudinea) Based on Mitochondrial Cytochrome c Oxidase Subunit I. Molecular Phylogenetics and Evolution, 9 (1), 156–162.

https://doi.org/10.1006/mpev.1997.0455

Siddall, M. E., Budinoff, R. B. & Borda, E. (2005) Phylogenetic evaluation of systematics and biogeography of the leech family Glossiphoniidae. Invertebrate Systematics, 19 (2), 105–112.

https://doi.org/10.1071/IS04034

Sket, B., Dovč, P., Jalžić, B., Kerovec, M., Kučinić, M. & Trontelj, P. (2001) A cave leech (Hirudinea, Erpobdellidae) from Croatia with unique morphological features. Zoologica Scripta, 30 (3), 223–229. https://doi.org/10.1046/j.1463-6409.2001.00065.x

Soós, A. (1969) Identification key to the leech (Hirudinoidea) genera of the World, with a catalogue of the species. VI. Family: Glossiphoniidae. Acta Zoologica Academiae Scientiarum Hungaricae, 15 (3- 4), 397–454.

Tamura, K., Stecher, G. & Kumar, S. (2021) MEGA11: Molecular Evolutionary Genetics Analysis version 11. Molecular Biology and Evolution, 38 (7), 3022–3027.

https://doi.org/10.1093/molbev/msab120

Tessler, M., de Carle, D., Voiklis, M. L., Gresham, O. A., Neumann, J. S., Cios, S. & Siddall, M. E. (2018) Worms that suck: Phylogenetic analysis of Hirudinea solidifies the position of Acanthobdellida and necessitates the dissolution of Rhynchobdellida. Molecular Phylogenetics and Evolution, 127, 129–134. https://doi.org/10.1016/j.ympev.2018.05.001

Tomilova, A. A., Lyubas, A. A., Kondakov, A. V., Vikhrev, I. V., Gofarov, M. Y., Kolosova, Y. S., Vinarski, M. V., Palatov, D. M. & Bolotov, I. N. (2020) Evidence for Plio-Pleistocene duck mussel refugia in the Azov Sea river basins. Diversity, 12 (3), 118.

https://doi.org/10.3390/d12030118

Tomoyasu, K., Cannizzaro, A. G. & Berg, D. J. (2025) Unexpected pathway for intercontinental movement into the Nearctic revealed by phylogenetic analyses. Zoologica Scripta.

https://doi.org/10.1111/zsc.12717

Torres-Carrera, G., Muñiz-Pareja, F. C., Maza-Acuña, A. N. & Oceguera-Figueroa, A. (2023). Broad phylogenetic analyses of the leech family Glossiphoniidae (Annelida: Clitellata) reveals two independent origins of kangaroo leeches. Biological Journal of the Linnean Society, 139 (2), 192–201. https://doi.org/10.1093/biolinnean/blad024

Trifinopoulos, J., Nguyen, L. T., von Haeseler, A. & Minh, B. Q. (2016) W-IQ-TREE: a fast online phylogenetic tool for maximum likelihood analysis. Nucleic Acids Research, 44, W232–W 235.

https://doi.org/10.1093/nar/gkw256

Trivalairat, P., Chiangkul, K. & Purivirojkul, W. (2019) Placobdelloides sirikanchanae sp. nov., a new species of glossiphoniid leech and a parasite of turtles from lower southern Thailand (Hirudinea, Rhynchobdellida). Zookeys, 882, 1–24. https://doi.org/10.3897/zookeys.882.35229

Tseng, C. T., Leu, J. H. & Cheng, I. J. (2018) On the genetic diversity of two species of the genus Ozobranchus (Hirudinida; Ozobranchidae) from the Atlantic and Pacific oceans. Journal of the Marine Biological Association of the United Kingdom, 98 (4), 955–960.

https://doi.org/10.1017/S0025315416001958

Tsubamoto, T., Kunimatsu, Y. & Nakatsukasa, M. (2015) A lower molar of a primitive, large hippopotamus from the lower Miocene of Kenya. Paleontological Research, 19 (4), 321–327.

https://doi.org/10.2517/2015PR015

Turner, G. F. (2024) Cladistic species definitions can lead to under-representation of biodiversity from adaptive radiations. Evolutionary Journal of the Linnean Society, 3 (1), kzae009.

https://doi.org/10.1093/evolinnean/kzae009

Utevsky, S. Y. & Trontelj, P. (2004) Phylogenetic relationships of fish leeches (Hirudinea, Piscicolidae) based on mitochondrial DNA sequences and morphological data. Zoologica Scripta, 33 (4), 375– 385. https://doi.org/10.1111/j.0300-3256.2004.00156.x

Villesen, P. (2007) FaBox: an online toolbox for fasta sequences. Molecular Ecology Notes, 7, 965– 968. https://doi.org/10.1111/j.1471-8286.2007.01821.x

Williams, J. I. & Burreson, E. M. (2006) Phylogeny of the fish leeches (Oligochaeta, Hirudinida, Piscicolidae) based on nuclear and mitochondrial genes and morphology. Zoologica Scripta, 35 (6), 627–639. https://doi.org/10.1111/j.1463-6409.2006.00246.x

Xu, Z., Yang, C., Gofarov, M. Y., Eliseeva, T. A., Kondakov, A. V., Yuan, H., Bolotov, I. N. & Yang, D. (2021) A new freshwater leech species from Asian Swamp Eel stocks in China. Parasitology Research, 120, 2769–2778. https://doi.org/10.1007/s00436-021-07228-2

Zettler, M. L. & Daunys, D. (2007) Long-term macrozoobenthos changes in a shallow boreal lagoon: comparison of a recent biodiversity inventory with historical data. Limnologica, 37 (2), 170– 185. https://doi.org/10.1016/j.limno.2006.12.004

Appendix A

H. kasmiana Oka, 1910 [ Russian Russia: Far East MN295425 MN312195 Bolotov et al. (2019) lineage]

H. khankiana Bolotov et al., 2019 Russia: Far East MN295420 MN312192 Bolotov et al. (2019)

H. marginata (O. F. Müller, Russia: Moscow MN295388 View Materials MN312178 View Materials Bolotov et al. (2019) 1773) [type species] Region

H. myanmariana Bolotov et al. , Myanmar MN295398 MN312182 Bolotov et al. (2019) 2019

H. schrencki Bolotov et al., 2019 Russia: Far East MN295415 MN312189 Bolotov et al. (2019)

P. biannulata (Moore, 1900) USA: North AF116021 AF115989 Apakupakul et al. (1999) Carolina

P. costata (F. Müller, 1846) Italy AY962461 AY962436 Siddall et al. (2005)

P. montifera (Moore, 1906) USA: Michigan AY047323 AY962420 Siddall et al. (2005)

P. multilineata Moore, 1953 USA: Louisiana AY962464 AY962439 Siddall et al. (2005)

P. papillifera (Verrill, 1872) USA: Tennessee AY047324 AY962421 Siddall et al. (2005)

P. parasitica (Say, 1824) Canada: Ontario AF003261 AF115990 Siddall and Burreson (1998); Apakupakul et al. (1999) P. pediculata Hemingway, 1908 USA: Michigan AY047327 AY962423 Siddall et al. (2005)