Bioacoustics of Ceratomyxa dactyloptena

Remarks. Ceratomyxa dactyloptena sp. nov. is the only ceratomyxid identified from D. orientalis and morphologically resembling C. drepanopsettae Awerinzew, 1908 , C. macapaensis Bittencourt, 2022 , and C. orientalis Dogiel, 1948 . Ceratomyxa drepanopsettae can be readily distinguished from C. dactyloptena sp. nov. by its substantially longer and thicker myxospores (Table 1 ). Its polar capsules are also larger, and notably spherical, contrasting with the pyriform polar capsules observed in C. dactyloptena sp. nov. (Table 1 ). Additionally, C. drepanopsettae was described from Pleuronichthys cornutus Temminck & Schlegel, 1846 collected in the Yellow Sea, off Qingdao, China , whereas C. dactyloptena sp. nov. infects D. orientalis and was identified from the South China Sea, off Sanya, China . Ceratomyxa macapaensis , a freshwater species and differs significantly from the new species by its smaller myxospores and smaller polar capsules (Table 1 ). Although both species possess pyriform polar capsules, their environmental origins clearly separate them: C. macapaensis was discovered in the Piririm River ( Brazil ), parasitizing Mesonauta festivus Heckel, 1840 , while C. dactyloptena sp. nov. is marine and occurs in Chinese coastal waters. Ceratomyxa orientalis possesses considerably longer and thicker myxospores compared to the new species (Table 1 ). Its polar capsules are also slightly larger (Table 1 ). Furthermore, C. orientalis was described from Sardinops sagax Jenyns, 1842 in the Sea of Japan ( Russia ) and clearly differs in both host and locality from C. dactyloptena sp. nov. Species Myxospore size (length × thickness; µm) Polar capsule size (length × width; µm) Posterior angle (°) Polar capsule shape Host Locality Reference C. dactyloptena n. sp. 6.4 ± 0.4 (5.7–7.0) × 30.0 ± 1.3 (27.2–32.8) 2.9 ± 0.3 (2.3–3.3) × 2.4 ± 0.3 (1.7–2.8) 152.9 ± 3.7 (146.2–158.9) Pyriform Dactyloptena orientalis Cuvier, 1829 South China Sea, off Sanya, China Present study C. drepanopsettae Awerinzew, 1908 11.3 (11–12) × 56.8 (52–62) 4.3 (4.0–4.5) ND Spherical Pleuronichthys cornutus Temminck & Schlegel, 1846 Yellow Sea, off qingdao, China Zhao and Song 2003 C. macapaensis Bittencourt da Silva, Hamoy, de Carvalho, da Silva, Videira, Carvalho & Matos, 2022 4.2 ± 0.5 × 22.75 ± 0.3 1.86 ± 0.3 × 1.63 ± 0.1 ND Pyriform Mesonauta festivus Heckel, 1840 Piririm River, Amapá, Brazil Bittencourt et al. 2022 C. orientalis Dogiel, 1948 7–11 × 33–72 3–3.3 ND ND Sardinops sagax Jenyns, 1842 Sea of Japan, Russia Eiras 2006 ; C. qingdaoensis Zhao, Al-Farraj, Al-Rasheid & Song, 2015 6.5 ± 0.5 (6.0–7.0) × 46.0 ± 2.8 (42.0–48.0) 2.8 ± 0.2 (2.5–3.0) 162–175 Spherical Argyrosomus argentatus Houttuyn, 1872 Yellow Sea, off Qingdao, China Zhao et al. 2015 C. saurida Zhao, Al-Farraj, Al-Rasheid & Song, 2015 9.7 ± 0.5 (9.0–10.5) × 42.7 ± 2.5 (39.5–47) 3.6 ± 0.4 (3.0–4.0) 130–165 Spherical Saurida elongata Temminck & Schlege, 1846 Yellow Sea, off Qingdao, China Zhao et al. 2015 C. hemitriptera Zhao, Al-Farraj, Al-Rasheid & Song, 2015 9.2 ± 0.3 (8.8–9.5) × 83.0 ± 3.3 (80.0–88.9) 4.8 ± 0.2 (4.0–5.0) 162–170 Spherical Hemitripterus villosus Pallas, 1814 Yellow Sea, off Qingdao, China Zhao et al. 2015 Among all valid Ceratomyxa species recorded in China , C. qingdaoensis Zhao, Al-Farraj, Al-Rasheid & Song, 2015 , C. saurida Zhao, Al-Farraj, Al-Rasheid & Song, 2015 , and C. hemitriptera Zhao, Al-Farraj, Al-Rasheid & Song, 2015 share some morphological resemblance to C. dactyloptena sp. nov. However, the new species can be reliably distinguished from these species based on a combination of spore dimensions, polar capsule characteristics, host, and locality data. The myxospore length of C. dactyloptena sp. nov. is nearly identical to that of C. qingdaoensis , yet the latter possesses markedly greater spore thickness (Table 1 ). The polar capsule length of C. qingdaoensis is comparable to that of the new species, but its polar capsules are spherical, whereas those of the new species are pyriform (Table 1 ). Additionally, C. qingdaoensis exhibits a larger posterior angle than C. dactyloptena sp. nov. and occurs in a different host ( Argyrosomus argentatus Houttuyn, 1872 ) and locality (Yellow Sea, off Qingdao, China ). Ceratomyxa saurida can be distinguished from C. dactyloptena sp. nov. by its larger myxospores and longer polar capsules (Table 1 ). Similar to C. qingdaoensis , the polar capsules of C. saurida are spherical, contrasting with the pyriform capsules of the new species. The posterior angle of C. saurida is slightly more variable and overlaps partially with that of the new species, but its host ( Saurida elongata Temminck & Schlege, 1846) and distribution (Yellow Sea, off Qingdao, China ) are distinct (Table 1 ). Ceratomyxa hemitriptera is readily separated from C. dactyloptena sp. nov. by having considerably thicker myxospores and larger polar capsules (Table 1 ). The myxospore length is also greater (Table 1 ). As with the other two species, C. hemitriptera has spherical polar capsules, while those of C. dactyloptena sp. nov. are pyriform. Moreover, C. hemitriptera infects a different host ( Hemitripterus villosus Pallas, 1814 ) and is found in a different geographic location (Yellow Sea, off Qingdao, China ).