A recent record of Romanogobioantipai (Actinopterygii, Cyprinidae, Gobioninae) from the Danube River in Bulgaria

• Published in: ZooKeys 2019-02 (825), p.105-122
• Main Authors: Bogutskaya, Nina G, Stefanov, Tihomir, Naseka, Alexander M, Oleg A Diripasko
• Format: Article
• Language: English
• Subjects: Cyprinidae; Identification and classification; Physiological aspects
• ISSN: 1313-2989; 1313-2970
• DOI: 10.3897/zookeys.825.32434

The Danube delta gudgeon, , has been considered to be extinct because there were no reliable recent observations. The latest record confirmed by a voucher specimen dating from 1992. We report here on a specimen of collected in 2016 in the Bulgarian sector of the Danube main stream using a bottom drift net at a depth of 8 m. The species determination is supported by morphological examination including discriminant and cluster analyses in comparison with three syntypes and five non-type specimens of , samples of the species complex and . most clearly differs from both and by proportional measurements (caudal peduncle depth, head width, eye horizontal diameter, and interorbital width), from also by the number of scales above and below the lateral line (6 and 4, respectively, (vs. commonly 5 and 3), and from , also by 8½ branched dorsal-fin rays (vs. 7½) and the vertebral caudal region longer than the abdominal vertebral region (abdominal+caudal vertebrae 19+21 or 20+21, vs. commonly 20+20 or variants with a caudal region shorter than the abdominal one). The possibility that represents a deep-water cophenotype of either or , cannot be excluded. The new record demonstrates that is still extant in the lower Danube but may be restricted to greater depths in the main channel and the deltaic branches.