taxonID	type	description	language	source
A64787F4FFAB6033D7FCFE164B8DFC53.taxon	biology_ecology	Host: The marine teleost, Chaeturichthys stigmatias Richardson, 1844 (Gobiiformes: Gobiidae). Locality: Specimens were collected from the Yellow Sea coastal waters near Qingdao city, Shandong Province, China. (36 ° 22 ' 47 " N, 120 ° 45 ' 13 " E) Infection site: Brain Prevalence: Infection was observed in 7 out of 20 fish (35 %).	en	Dong, Jilei, Jiang, Yanhua, Tan, Zhijun, Yao, Lin, Liu, Pengxiang, Zhao, Xiaojing, Zhang, Jinyong (2026): Kudoa stigmatias sp. nov. (Cnidaria: Multivalvulida) infecting the brain of the marine fish Chaeturichthys stigmatias (Gobiiformes: Gobiidae) in the Yellow Sea, China. Zootaxa 5750 (3): 429-437, DOI: 10.11646/zootaxa.5750.3.8, URL: https://doi.org/10.11646/zootaxa.5750.3.8
A64787F4FFAB6033D7FCFE164B8DFC53.taxon	materials_examined	Material deposition: Specimens preserved in 95 % ethanol were deposited in the Laboratory of Aquatic Parasitology and Microbial Resources, School of Marine Science and Engineering, Qingdao Agricultural University (voucher number MTR 20240316). The obtained LSU rDNA sequences have been submitted to the GenBank database (accession number PV 166901).	en	Dong, Jilei, Jiang, Yanhua, Tan, Zhijun, Yao, Lin, Liu, Pengxiang, Zhao, Xiaojing, Zhang, Jinyong (2026): Kudoa stigmatias sp. nov. (Cnidaria: Multivalvulida) infecting the brain of the marine fish Chaeturichthys stigmatias (Gobiiformes: Gobiidae) in the Yellow Sea, China. Zootaxa 5750 (3): 429-437, DOI: 10.11646/zootaxa.5750.3.8, URL: https://doi.org/10.11646/zootaxa.5750.3.8
A64787F4FFAB6033D7FCFE164B8DFC53.taxon	etymology	Etymology: The species name “ stigmatias ” is derived from the specific epithet of its host.	en	Dong, Jilei, Jiang, Yanhua, Tan, Zhijun, Yao, Lin, Liu, Pengxiang, Zhao, Xiaojing, Zhang, Jinyong (2026): Kudoa stigmatias sp. nov. (Cnidaria: Multivalvulida) infecting the brain of the marine fish Chaeturichthys stigmatias (Gobiiformes: Gobiidae) in the Yellow Sea, China. Zootaxa 5750 (3): 429-437, DOI: 10.11646/zootaxa.5750.3.8, URL: https://doi.org/10.11646/zootaxa.5750.3.8
A64787F4FFAB6033D7FCFE164B8DFC53.taxon	discussion	Remarks: To date, 11 Kudoa species have been reported to parasitize fish brain tissue (Eiras et al. 2014; Li et al. 2022; Sakai et al. 2019). Among them, 7 species have more than 4 shell valves, including K. chaetodoni (7 – 9), K. lemniscati (7 or 8), K. lethrini (6 or 7), K. prunusi (predominantly 5 but occasionally 6), K. yasunagai (7), K. neurophila (5), and K. miyakoensis (8). Therefore, we conducted a detailed morphological comparison between K. stigmatias sp. nov. and all cerebral-infecting Kudoa species with exactly four shell valves (Table 1). Compared with K. cerebralis and K. paralichthys, K. stigmatias sp. nov. has significantly larger spores (7.1 – 8.8 μm> 4.8 to 5.8 μm). The spore length of K. stigmatias sp. nov. is also slightly greater than that of K. lutjanus (7.1 – 8.8 μm vs. 6.3 – 7.9 μm). While K. iwatai exhibits similar spore length to K. stigmatias sp. nov., distinct differences are observed in spore width and thickness (7.0 – 10.0 × 7.4 – 11.1 μm vs 12.1 – 13.8 × 10.6 – 12.5 μm). Meanwhile, K. stigmatias sp. nov. differs significantly from other Kudoa species in polar capsule morphology, particularly in the number of polar filament coils (1 – 2 vs. 2 – 3). In addition, K. stigmatias sp. nov. represents hemispherical in lateral view, whereas K. paralichthys appears ovoid, and K. cerebralis, K. lutjanus, and K. iwatai display a drawstring-pouch-like shape in lateral view. Therefore, a strict comparative analysis of Kudoa species infecting fish brains worldwide reveals that K. stigmatias sp. nov. is morphologically distinct from all previously described species. Molecular and Phylogenetic Analyses The partial LSU rDNA sequence of K. stigmatias sp. nov., obtained via the employed primer amplification, is 800 bp in length. BLAST analysis showed the highest sequence similarity (90.74 %) with Kudoa pilosa (LC 777080), which was isolated from the muscle tissue of Helicolenus hilgendorfii in China. Sequence similarity and genetic distance were analyzed among species with high sequence similarity and brain-infecting Kudoa species. The analysis showed that the sequence similarity and genetic distance ranged from 76.4 % / 0.236 to 55.3 % / 0.447 (Table 2). Phylogenetic analysis using both Bayesian Inference (BI) and Maximum Likelihood (ML) methods yielded similar clustering relationships. The phylogenetic reconstruction demonstrated that K. stigmatias sp. nov. clusters with muscle-infecting Kudoa species, including Kudoa quraishii Mansour et al., 2014 (KF 830722) from India, Kudoa trachuri Matsukane et al., 2011 (LC 640007) from the Philippines, Kudoa scomberi Li et al., 2013 (AB 693045) from Japan, Kudoa thunni Matsukane et al., 2011 (LC 200507) from Japan, and Kudoa crumena Iversen & Van Meter, 1976 (FJ 417057) from Australia, indicating a close evolutionary relationship with them. In contrast, this novel species shows distant relationships with cerebral-infecting Kudoa species, and this clade is supported by high statistical values (Figure 3).	en	Dong, Jilei, Jiang, Yanhua, Tan, Zhijun, Yao, Lin, Liu, Pengxiang, Zhao, Xiaojing, Zhang, Jinyong (2026): Kudoa stigmatias sp. nov. (Cnidaria: Multivalvulida) infecting the brain of the marine fish Chaeturichthys stigmatias (Gobiiformes: Gobiidae) in the Yellow Sea, China. Zootaxa 5750 (3): 429-437, DOI: 10.11646/zootaxa.5750.3.8, URL: https://doi.org/10.11646/zootaxa.5750.3.8
