Gyrodactylus diptychi, Hao & Zhang & Arken & Wang & Shi & Zhang & Yue, 2024

Hao, Cui-lan, Zhang, Wen-run, Arken, Kadirden, Wang, Jin-pu, Shi, Cai-xia, Zhang, Li & Yue, Cheng, 2024, Identification of a new species of Gyrodactylus von Nordmann, 1832 (Monogenoidea Gyrodactylidae) isolated from Diptychus maculatus in Yarkand River, Xinjiang, China, International Journal for Parasitology: Parasites and Wildlife 24, pp. 100949-100949 : 100949-

publication ID	https://doi.org/ 10.1016/j.ijppaw.2024.100949
persistent identifier	https://treatment.plazi.org/id/039C3B54-BF01-1017-FC91-FCC2FBEAA81D
treatment provided by	Felipe
scientific name	Gyrodactylus diptychi
status	sp. nov.

Treatment

3.2. Morphological characterization of Gyrodactylus diptychi View in CoL n sp.

In order to clarify the morphological characteristics of Gyrodactylus from Diptychus maculates . Descirption based on 28 flattned specimens ( Figs. 1 View Fig and 2 View Fig , Table 2). Body “gourd-like” shape, fusiform, total body length 436.4 (369.4–493.6) long, 108.8 (101.1–115.2) wide. Pharynx bulb 27.5 (16.8–29.7) long, 22.3 (14.6–27.2) wide. The cecum not spread to anterior edge of the testes. MCO 16.6 (8.03–19.8) long, 15.6 (7.6–17.7) wide, armed with one central spine, two large spines and four small spines, posterior to pharyngeal bulb ( Figs. 1C View Fig & 2D View Fig ). Hamuli 83.7 (78.5–86.9) long, shafts 60.2 (56.7–63.0) long, tapered end; points 35.6 (32.3–38.2) long; proximal shaft 9.5 (9.0–10.2) wide, curved ( Figs. 1A View Fig , 2A and 2B View Fig ); Aperture distance 27.4 (25.7–30.6) long, hamulus aperture angle 38.5 ◦ (32.6 ◦ –48.7 ◦), hamulus root 28.6 (21.9–32.7) long, inward and curved ( Figs. 1B View Fig & 2C View Fig ). Dorsal bar 20.1 (18.9–25.3) long, 2.5 (1.8–3.4) wide, the middle flat straight, short, and both ends were thick and big ( Figs. 1D View Fig and 2E View Fig ). Ventral bar 38.0 (30.7–41.5) long, 13.8 (11.5–15.2) wide, with short processes and medium triangular membrane, ventral bar processes 3.1 (2.8–3.4) long, ventral bar membrane 24.1 (19.2–26.3) long, “U” shape with a weak central ridge ( Figs. 1E View Fig & 2F View Fig ). Marginal hook 35.0 (32.5–37.9) long, hook shaft 29.1 (27.1–31.9) long, rounded bottom; marginal hook sickle 6.3 (5.3–7.2) long, sickle shaft approximately perpendicular to the base, curved, tilted forward and aligned the toe; sickle point 2.9 (2.4–3.7) wide, sickle distal 2.7 (2.1–3.7) wide. Marginal hook toe 1.7 (1.1–2.5) long, marginal hook aperture 4.7 (2.0–5.9) long, hook instep 1.0 (0.8–1.4) high, and filament loop 1.0 (0.8–1.4) long ( Fig. 1F and G View Fig & 2G & 2H View Fig ).

3.3. Remarks

To clarify any features of the newly identified G. diptychi n. sp. distinctive from already known members of Gyrodactylus , we compared the morphological features of G. diptychi n. sp. with G. hemivicinus Ergens et Daniyarov, 1976 ; G. kafirniganensis Ergens and Karabekova (1980) and G. montanus Gusev (1985) . We also compared the marginal hooks of G. diptychi n. sp. with 12 Gyrodactylus , which are parasitic to Schizothoracinae . As depicted in Fig. 3 View Fig , G. diptychi n. sp. exhibited similar marginal hook morphology to the G. gymnodiptychi Zhang et al., 2023 isolated from Gymnodiptychus dybowskii, Kessler, 1874 ; However, Gyrodactylus diptychi n. sp. had a slender sickle, a longer marginal hook toe and a longer marginal hook proximal ( Fig. 3 View Fig ). As depicted in Fig. 4 View Fig ,

3 View Fig

G. diptychi n. sp. exhibited similar ventral bar morphology to the G. hemivicinus ; on both species, their dorsal bars were short, but the dorsal bar of G. diptychi n. sp. was flat straight in middle and thick and big at both ends. The MCO of G. diptychi n. sp. had only one spine that was fewer than G. hemivicinus ( Fig. 4A and B View Fig ). Gyrodactylus diptychi n. sp. exhibited same number of MCO’ spines and exhibited similar ventral bar morphology to the G. hemivicinus and G. kafirniganensis ( Fig. 4A and C View Fig ); however, the dorsal bar of G. diptychi n. sp. was short and flat straight in middle, and thick and big at both ends. Gyrodactylus diptychi n. sp. exhibited similar hamuli morphology to the G. montanus ; on both

Note: “–” means no date. species, their MCO armed with one central spine, two large spines, and four small spines; however, the dorsal bars of G. montanus had a hollow at both ends of the projection ( Fig. 4A and D View Fig ). The results indicated G. diptychi n. sp. having a short dorsal bar with thick and big ends that was distinctive from 12 species of gyrodactylid isolated from the fish subfamily Schizothoracinae .