Nereis oligohalina. Non-type male A–C, F–J, N (ECOSUR–OH–P0761); non-type partially transformed male D, L–M (ECOSUR P2827); non-type partially transformed female E, K (ECOSUR P2827). A Whole specimen, dorsal view B Anterior end, dorsal view C Posterior end, dorsal view D, E Anterior ends, dorsal view F Parapodium 1, anterior view G Parapodium 6, anterior view H Parapodium 10, frontal view I Parapodium 18, anterior view J Parapodium 31, anterior view K Parapodium 10, anterior view L Parapodium 24, anterior view M Parapodium 52, anterior view N Sesquigomph natatory chaetae, parapodium 31. Scale bars: 1 mm (A, D–E); 0.5 mm (B); 0.2 mm (C); 0.1 mm (F–M); 10 μm (N).