Integrative taxonomy and phylogenetic analyses of two species (Myxozoa, Ceratomyxidae) from the China Sea, including a new species description.

Two species of (Myxozoa: Ceratomyxidae) from teleosts in the China Sea are investigated using an integrative approach which combines morphological characteristcs, parasitic traits, and molecular data including small subunit ribosomal DNA (SSU rDNA) and internal transcribed spacer (ITS) regions. A novel species, , was identified from the gallbladder of Oriental flying gurnard Cuvier, 1829, while Zhang, Zhao, Yang & Yang, 2019 was found in the gallbladder of Mottled spinefoot Houttuyn, 1782 and Mozambique tilapia Peters, 1852. Mature myxospores of exhibit a crescent shape in sutural view, with dimensions of 30.0 ± 1.3 (27.2-32.8) µm in thickness, 6.4 ± 0.4 (5.7-7.0) µm in length, and a posterior angle of 152.9 ± 3.7° (146.2-158.9°). Pyriform polar capsules measured 2.9 ± 0.3 (2.3-3.3) µm long and 2.4 ± 0.3 (1.7-2.8) µm wide, with polar filaments coiled in 3-4 turns. The SSU rDNA sequence of was distinct from all known myxosporeans, showing the highest similarity (87.9%) and the shortest genetic distance (0.1209) with Kalatzis, Kokkari & Katharios, 2013. Molecular analyses revealed intraspecific variation among strains, with ITS rDNA being more sensitive than SSU rDNA in detecting these differences. Phylogenetic analysis placed in a clade with Heiniger, Gunter & Adlard, 2008, while all strains clustered together, forming a sister clade to Gunter, Whipps & Adlard, 2009. Furthermore, the phylogenetic results indicated that ceratomyxid diversification is influenced not only by host specificity but also by geographic distribution.