Helobdella stagnalis ( 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 : 52

Helobdella stagnalis ( Linnaeus, 1758)

( Figures 3G–H–I )

Material examined: Raseika (Raseiniai) (Nr. 1) n=12, 9.viii.2019; Klibiai (Kretinga) (Nr. 7), n=15, 4.vii.2018; Grūšlaukė (Palanga) (Nr. 9), n=9, 5. vii. 2019; Tūbinė (Šilalė) (Nr. 10), n=10, 15.vii. 2018; Kirneilė (Molėtai) (Nr. 13), n=11, 4.viii.2018; Maišia (Garliava) (Nr. 15), n=12, vii–viii. 2019; Ronžė (Palanga) (Nr. 17), n=9, 2.viii.2018; Šventoji (Kretinga) (Nr. 20), n=10, 7.viii.2018; Ilgis (Ignalina) (Nr. 33), n=5, 21.viii.2018.

Diagnosis: Body flat, leaf–shape. 10 mm length, and 2–4 mm width. Body whitish with numerous tawny spots on dorsal surface. One pair of eyespots and a chitinous nuchal scute ( Tiberti and Gentilli 2010, Ben Ahmed et al. 2015a) on dorsal surface in anterior region are clearly visible ( Figs. 3G, H ).

Habitat: Common leech in ponds and small slow flowing rivers. Specimens with developing cocoons and juveniles attached to the ventral surface were found from May to August ( Fig. 3I ). Juveniles were about 1 mm length in May, and their number on the adults varied from 1 to 12.

Distribution: Helobdella stagnalis ( Linnaeus, 1758) , is one of the most widely distributed species of freshwater leeches, it has been reported from all continents except Australia ( Platt et al. 1993; Ben Ahmed et al. 2015b) however it may represent a complex of multiples species (see Iwama et al 2019). Previously, this species was recorded in Curonian lagoon, Lithuania ( Szidat 1926; Gasiūnas 1959; Zettler and Daunys 2007) and based on our results, ( Table 1 ) it is clear that H. stagnalis is widespread throughout the country.

Figures

FIGURE 3. Freshwater leeches in Lithuania: dorsal view of Helobdella stagnalis anterior part of body (G), whole body (H) and juveniles attached to the ventral part of body (I).