Helobdella europaea Kutschera, 1987

Helobdella europaea Kutschera, 1987

= Helobdella striata Kutschera (1985): 470 , Abb. 1, 2a-c, 3, 4, 5a-d, 6 [unavailable name: primary homonym of Helobdella striata Ringuelet, 1943 ; holotype ZMUH H. striata ; type locality: “Schobbach/Moosbach bei Vörstetten, nördlich von Freiburg i. Br., Bundesrepublik Deutschland ” ( Germany: Schobbach/Moosbach stream near Vörstetten, 48.0419°N, 7.8544°E, north of Freiburg im Breisgau); first out-door record in Europe].

= Helobdella punctatolineata Mienis (1986): 153 [misidentification; non Moore, 1939; first record in Israel].

= Helobdella europaea Kutschera (1987): 322 , fig. 1 [nomen novum for Helobdella striata Kutschera, 1985 ].

= Helobdella punctatolineata Moustafa (1994): 51 , figs 1-24 [misidentification; non Moore, 1939; first record in Egypt].

= Helobdella papillornata Govedich & Davies (1998): 46 , figs 1a-d, 2a-c [junior synonym; synonymized by Pfeiffer et al. (2004) and Siddall & Budinoff (2005); holotype NMV F83523 View Materials ; type locality: Aura Vale Lake located 40 km east of Melbourne, 37.9167°S, 145.3833°E, Victoria, Australia; first record in Australia].

= Placobdella godavariensis Mandal & Dhani (2015): 237 , fig. 1A-D [syn. nov.; holotype ZSI An 3812/1; type locality: Ganga Ghat, 20.0014°N, 73.7869°E, Godavari River   GoogleMaps , Nasik, Maharashtra, India; first record in India].

Figures 4 View Figure 4 , 8 View Figure 8

Native range: Unknown but most likely occurs somewhere in South America ( Kutschera 2004); morphologically similar specimens occur in Peru and Brazil ( Shain et al. 2007: fig. 5A, as Helobdella striata ; De-Carli et al. 2014: fig. 4, as Helobdella triserialis ).

Non-native range: Australia, China: Taiwan, Egypt, Fiji, Germany, Hungary, India: Maharashtra (first country-level record), Israel, Morocco, Netherlands, New Zealand, Palestine, Portugal, South Africa, Spain, and the USA: Hawaii, California and Mississippi ( Kutschera 1985; Mienis 1986; Kutschera 1987; Moustafa 1994; Govedich and Davies 1998; Pfeiffer et al. 2004; Van Haaren et al. 2004; Siddall and Budinoff 2005; Bely and Weisblat 2006; Jueg 2008; Lai et al. 2009; Reyes-Prieto et al. 2014; Mandal and Dhani 2015; Málnás et al. 2016; Richardson et al. 2017b; Mabrouki et al. 2019; Perera et al. 2019; Ferreira et al. 2022; Rashni et al. 2024; Adawi et al. 2025) ( Figure 8 View Figure 8 ). A few records of this species from in-door aquaria in France, Germany, and Ukraine ( Kutschera 2004; Lecaplain and Noël 2015; Morhun et al. 2021) do not belong to established (naturalized) populations and should not be used as point-occurrence records for mapping of the non-native range.

Ecological notes: This species was recorded in a phoretic association with freshwater turtles in the USA ( Richardson et al. 2017b) and Europe ( Perera et al. 2019). It feeds on small aquatic invertebrates such as oligochaet worms ( Tubifex sp. ), freshwater snails, and crustaceans, as well as on dead bodies of aquatic vertebrates (fish and amphibians) ( Kutschera 2004).

Taxonomic comments: The new synonymy proposed here is as follows: Helobdella europaea Kutschera, 1987 [= Placobdella godavariensis Mandal & Dhani, 2015 syn. nov.].

Records of Helobdella punctatolineata Moore, 1939 in Egypt and Israel in the 1980s (see Mienis 1986; Moustafa 1994) can be linked to Hel. europaea . At least, a thorough description and illustrations of specimens from Egypt ( Moustafa 1994) reveal that they indeed belong to the latter species. In turn, Hel. punctatolineata is endemic to Puerto Rico ( Moore 1939; Sawyer and Kinard 1980) and could be distinguished from Hel. europaea by having smaller dorsal papillae ( Moore 1939). El-Shimy (1994) concluded that Hel. punctatolineata from Egypt is a “polymorphism” (morphological form) of Helobdella conifera ( Moore, 1933) . However, this conclusion cannot be accepted, because the latter species does not share any kind of longitudinal markings pattern, including dark paramedian stripes ( Nesemann and Neubert 1999).

Utevsky and Mazepa (2005) described a record of Helobdella triserialis (Blanchard, 1849) from a private aquarium in Ukraine. They noted that these specimens differ from Hel. europaea by having paramedian stripes with two transverse interruptions at the anterior end (vs continuous stripes) ( Utevsky and Mazepa 2005). Conversely, sequenced specimens of Hel. europaea from other regions may have broken paramedian stripes (e.g., in Fiji; Rashni et al. 2024: fig. 1d, f). Moreover, Siddall and Borda (2003) proposed this feature as a diagnostic character of both Helobdella triserialis and Hel. papillornata [= Hel. europaea ]. These authors stated that “ H. triserialis (sensu stricto) and H. papillornata exhibit transverse interruptions in the longitudinal pigmentation in a manner not seen for any North American leech ( Fig. 4 View Figure 4 )” ( Siddall and Borda 2003: 32).

Discussion

New data on mollusc-associated leeches from India

Three leech species were recorded from the mantle cavity of freshwater molluscs in Manipur, that is, Alboglossiphonia pahariensis , Hemiclepsis myanmariana , and Helobdella octatestisaca . The first species was originally described from India and Nepal but later on it was also recorded from Myanmar ( Nesemann et al. 2007; Bolotov et al. 2022b; see Figure 5 View Figure 5 ). Here, we show that A. pahariensis occurs in the mantle cavity of two viviparid gastropod species in Manipur. Juvenile leeches recorded from the mantle cavity of the freshwater snail species Pila virens (Lamarck, 1822) ( Gastropoda: Ampullariidae ) in Lake Inle, Myanmar most likely also belong to this species ( Oka 1922: as A. heteroclita (Linnaeus, 1761) ; Bolotov et al. 2022b). Additionally, this leech was recorded as an inhabitant of chironomid burrows in a sponge body in India ( Bolotov et al. 2022b). Our new data reveals that A. pahariensis is a morphologically and genetically variable species, having at least two distinct phylogenetic lineages with different dorsal markings pattern: (1) the local lineage from Manipur (darker coloration with black longitudinal stripes); and (2) the widespread lineage from other places of India, Nepal, and Myanmar (light coloration with longitudinal series of dark spots). At first glance, the darker-colored (melanic) lineage from Manipur may have evolved under specific habitat conditions, that is, eutrophic stagnant water bodies with bottom covered by black silt substrate and decaying macrophyte remains. Theoretically, the latter lineage may represent a specific ecological or geographic race but available data are too fragmentary for a reasoned decision on this issue. There are some examples of cryptic coloration (camouflage) in glossiphoniid leeches with intraspecific light-colored and melanic forms that can be linked to the different type of substrate, although these forms occur in the same population and have identical mtDNA sequences ( Bolotov et al. 2023b).

Hem. myanmariana is an obligate mussel-associated leech, using bivalves as secondary host/shelter and fishes as primary host ( Bolotov et al. 2019). It seems to prefer Lamellidens species as bivalve host but it was also recorded from freshwater mussels belonging to other genera such as Indonaia Prashad, 1918 View in CoL , Leoparreysia Vikhrev, Bolotov & Aksenova, 2017 View in CoL , Radiatula Simpson, 1900 View in CoL , and Yaukthwa Konopleva et al., 2019 View in CoL ( Bolotov et al. 2019). Here, we present a few new records of this species from Myanmar, including its first occurrence from the mantle cavity of Sinanodonta pacifica View in CoL , an alien freshwater mussel (see Supplementary information online, Table S1). Hem. myanmariana is likely to be endemic to the Western Indochina Subregion, because all its records are situated between the Chindwin/ Irrawaddy and Salween drainage basins (see Figure 7 View Figure 7 ) except for, perhaps, samples from Assam (see Taxonomic account for detail). Our new records from Manipur are also confined to the Chindwin/ Irrawaddy Basin. Samples from Manipur are in well agreement with those from Myanmar morphologically.

Hel. octatestisaca was not previously recorded as an endosymbiont of molluscs. Here, we show that it occurs in the mantle cavity of two viviparid gastropod species in Manipur (see Table 1). Therefore, this species can be considered a facultative snail-associated leech. Earlier, Hel. octatestisaca was recorded attached to other leech species, freshwater turtles, and to the surface of shell and operculum of a freshwater snail ( Lai and Chen 2010; Richardson et al. 2017a; Perera et al. 2019).