First record of the land planarian species Rhynchodemus sylvaticus in a nature of Czechia

Rhynchodemus sylvaticus is a small species of land planarian with a cosmopolitan distribution. It is a successful invasive species with an unclear origin - several possible centers of origins are known, specificaly the Neotropical and Indonesian regions. The Nearctic region, where Rhynchodemus sylvaticus was described, is less rich on members of this genus. European origin of this species was also considered by some authors. The current distribution in Europe is known from various countries, mainly from citizen science-based reports. Despite its wide distribution in Europe and its generic cosmopolitan characteristics, this species has not been reported in the natural environment of Czechia yet. The only mentions regarding Rhynchodemus sylvaticus are older reports from Prague and Chotěboř, which contain greenhouse findings. Closest report in non-anthropogenic environment is located in Dunajské luhy area in Slovakia. A set of twelve specimens with pair of ocelli, pointy head,uniformly brown base color with darker longitudinal stripes accompanied by saddle-like patterning above the pharyngeal region in larger animals, and a milky ventral side was found in the Úpor-Černínovsko natural reserve in the Central Bohemian region during fieldwork focused on the freshwater triclad Girardia tigrina in summer 2023. 2D reconstructions of the sexual apparatus were processed. Eight subadults showed various levels of sexual maturation. No genital swelling associated with the presence of large male atrium was observed externally. No animal was confirmed as male mature histologically. The tendency of female organs to develop and differentiate first before male organs is well-known from previous results in older works regarding this hermaphroditic species. Histology reports of sexually fully mature animals are scarce in general, but external appearance can be used for successful identification as well, due to characteristic of coloration and patterning in other rhynchodemids. Poster is accopmanied by interactive WSI imagery First record of the land planarian species Rhynchodemus sylvaticus (Leidy,1852) in a naturalized area of Czechia