A new species of freshwater flatworm (Platyhelminthes, Tricladida, Dendrocoelidae) inhabiting a chemoautotrophic groundwater ecosystem in Romania

Giacinta Angela Stocchino,Serban Mircea Sarbu,Mahasaru Kawakatsu,Renata Manconi,Ronald Sluys

doi:10.5852/ejt.2017.342

Giacinta Angela Stocchino, Serban Mircea Sarbu + Show 3 more

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https://doi.org/10.5852/ejt.2017.342

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Abstract

We report the description of a new species of freshwater flatworm of the genus Dendrocoelum inhabiting the chemoautotrophic ecosystem of Movile Cave as well as several sulfidic wells in the nearby town of Mangalia, thus representing the first planarian species fully described from this extreme biotope. The species was also found in non-sulfidic wells localized in villages in the vicinity of the cave with a total of nine examined populations. Dendrocoelum obstinatum Stocchino & Sluys, sp. nov. represents the first triclad being able to live in both sulfidic and non-sulfidic waters. Among the fauna of the Mangalia sulfidic ecosystem it is the only species found also outside of the current boundaries of the sulfidic aquifer. One possible explanation of this peculiar distribution is that the new species is limited to the old boundaries of the sulfidic aquifer. The latter became much smaller during the hydrogeological history of the region, so that D. obstinatum may be considered to be an indicator of the extension of the sulfidic aquifer in the past of the Mangalia region. In the context of a biogeographic discussion on the distribution of the genus Dendrocoelum we provide an annotated checklist of species reported from Romania.

Highlights

The freshwater planarian fauna of Romania, in particular from groundwater habitats, has been the subject of several studies that were developed since the 1920s, notably by De Beauchamp and Codreanu (De Beauchamp 1928, 1929, 1932, 1949; Codreanu 1929, 1943, 1949; see Del Papa 1965; Codreanu & Balcesco 1967a, 1967b, 1967c, 1970; Gourbault 1967a, 1967b)
In this paper we present the description of a new species of Dendrocoelum inhabiting the chemoautotrophic ecosystem of Movile Cave as well as several sulfidic hand-dug wells nearby the cave, representing the first fully described triclad from this extreme biotope
Dendrocoelum obstinatum Stocchino & Sluys, sp. nov. is characterized by: a male atrium extending ventrally to form a cervix-like structure projecting into the common atrium; a proximal tract of the bursal canal with an almost non-existent lumen; testes extending to the far posterior end of the body; a Balkan type of adenodactyl, with a length approximately equal to that of the penis; the penis being in a dorsal position and the adenodactyl located ventrally; the proximal half of the bursal canal being surrounded by a subepithelial layer of longitudinal muscle, while its distal half is surrounded by a subepithelial layer of circular muscles, followed by a layer of longitudinal fibres

Summary

Introduction

The freshwater planarian fauna of Romania, in particular from groundwater habitats, has been the subject of several studies that were developed since the 1920s, notably by De Beauchamp and Codreanu (De Beauchamp 1928, 1929, 1932, 1949; Codreanu 1929, 1943, 1949; see Del Papa 1965; Codreanu & Balcesco 1967a, 1967b, 1967c, 1970; Gourbault 1967a, 1967b). Subterranean triclads from Romania belong to two genera of the family Dendrocoelidae (Dendrocoelum Örsted, 1844, Polycladodes Steinmann, 1910) and two genera of Planariidae (Atrioplanaria De Beauchamp, 1932, Crenobia Kenk, 1930) (cf Gourbault 1972, 1986). With respect to epigean species, the following taxa were recorded: Dugesia sp., Schmidtea lugubris (Schmidt, 1861), S. polychroa (Schmidt, 1861), Polycelis felina (Dalyell, 1814), P. nigra (Müller, 1774), and P. tenuis Ijima, 1884 (cf. Dahm & Gourbault 1978)

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