Central European parasitic flatworms of the family Renicolidae Dollfus, 1939 (Trematoda: Plagiorchiida): molecular and comparative morphological analysis rejects the synonymization of Renicola pinguis complex suggested by Odening.

The Renicolidae are digenean parasites of piscivorous and molluscivorous birds. Although they exhibit few morphological autapomorphies and are highly variable, the numerous suggested re-classifications within the family have never been supported by any molecular analyses. We address the possible synonymization of species within the Renicola pinguis complex suggested previously by Odening. We provide and analyse sequences of two nuclear (ITS2, 28S rDNA) and two mitochondrial (CO1, ND1) DNA loci of central European species of the Renicolidae, namely Renicola lari, Renicola pinguis and Renicola sternae sp. n., and we also provide first sequences of Renicola sloanei. The combined molecular and comparative morphological analysis confirms the previously questioned validity of the three Renicola spp. of highly similar morphology, which display strict niche separation in terms of host specificity and selectivity. We identify two previously unreported clades within the genus Renicola; however, only one of them is supported by the analysis of adult worms. We also provide comparative measurements of the three examined closely related central European renicolids, and describe the newly proposed tern-specialized species Renicola sternae sp. n., which was previously repeatedly misidentified as Renicola paraquinta. Based on the extensive dataset collected in 1962-2015, we update the host spectrum of Renicolidae parasitizing central European birds (Renicola bretensis, R. lari, Renicola mediovitellata, R. pinguis, Renicola secunda and R. sternae sp. n.) and discuss their host-specific prevalence and intensity of infections.