Yunlu, Melek ZeybekCil, Eylem Aydemirvan Haaren, TonYildiz, Seray2025-03-232025-03-2320231300-15902148-3140https://doi.org/10.12714/egejfas.40.4.10https://search.trdizin.gov.tr/tr/yayin/detay/1217384https://hdl.handle.net/11486/5105The aim of this paper is to contribute to the aquatic Oligochaeta fauna of Turkiye. The study area selected for this research is Karasu Stream, located in the Black Sea Region of Turkiye, in the province of Sinop. Benthic macroinvertebrate samples were collected on a monthly basis between February 2013 and January 2014 from 10 selected stations in the study area. As a result of the study, Rhyacodrilus falciformis Bretscher, 1901 is reported as a new record for the Oligochaeta fauna of Turkiye. Besides being recognized as a new record species, this record also extends the species' distribution area to the Asian part of Turkiye. Additionally, this study provides detailed information on the biological, ecological, and morphometric characteristics, as well as the distribution of R. falciformis, identified as a new record for the fauna of Turkiye.eninfo:eu-repo/semantics/openAccessOligochaetaRhyacodrilinaenew recordKarasu StreamSinopTurkiyeArticle40430430910.12714/egejfas.40.4.10N/A1217384WOS:001255120500010N/A