Purpose

There are currently nine monogenoidean species of Rhabdosynochus infecting the gill lamellae of wild and cultured centropomid fishes from tropical and subtropical waters of the western Atlantic and eastern Pacific Oceans. The purpose of the present study was to describe the morphological distinctiveness of two new species of Rhabdosynochus found on the cultured Centropomus viridis collected from floating cages from the Mexican eastern Tropical Pacific in 2018.

Methods

monogenoideans were fixed with 4–5% formalin solution, observed and measured as temporary or permanent mounts stained with Gomori’s trichrome, and mounted in Canada balsam. Other specimens were mounted on slides using a mixture of lactic acid (LA) and glycerin-ammonium picrate (GAP) and then remounted in Canada balsam to obtain measurements of the haptoral structures and copulatory complex. Illustrations were prepared with the aid of a drawing tube using a Leica microscope DM 2500 with Nomarski interference contrast.

Results

Rhabdosynochus viridisi n. sp. is mainly differentiated from all other congeneric species in the shape and size of their copulatory complexes, i.e., length 75–105 µm vs. 45–55 µm in R. alterinstitus, 26–44 µm in R. volucris, 19–22 µm in R. lituparvus, 21–37 µm in R. siliquaus, 48–75 µm in R. hargisi, 37–44 µm in R. hudsoni and 44–61 µm in R. guanduensis. Rhabdosynochus pacificus n. sp. differs from all other species of the genus in having an accessory piece (one subunit) distally twisted.

Conclusions

Based on the morphometric differences of the two new species described above, the number of valid species of Rhabdosynochus has now increased to 11. These two new species of Rhabdosynochus represent the first described species of the genus on C. viridis.

中文翻译：

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Rhabdosynochus Mizelle 和 Blatz 的新种 1941（Monogenoidea：Diplectanidae）来自墨西哥东热带太平洋养殖的 Centropomus viridis（Perciformes）的鳃

目的

目前有 9 种单基因纲的 Rhabdosynochus感染来自西大西洋和​​东太平洋热带和亚热带水域的野生和养殖的中心类鱼类的鳃片。本研究的目的是描述2018 年在从墨西哥东热带太平洋的漂浮网箱中收集的培养的Centropomus viridis上发现的两个新种Rhabdosynochus的形态特征。

方法

monogenoideans 用 4-5% 福尔马林溶液固定，观察和测量为用 Gomori 三色染色的临时或永久安装，并安装在加拿大香脂中。其他标本使用乳酸 (LA) 和甘油-苦味酸铵 (GAP) 的混合物安装在载玻片上，然后重新安装在加拿大香脂中，以获得对触觉结构和交配复合物的测量。使用带有 Nomarski 干涉对比的 Leica 显微镜 DM 2500 借助绘图管准备插图。

结果

Rhabdosynochus viridisi n. sp. 主要是从在形状和其交配的复合物的大小，即，长度的所有其他同类物种分化75-105微米与45-55微米R. alterinstitus，26-44微米R. volucris，19-22微米R. lituparvus，R. siliquaus 为21–37 µm，R. hargisi 为48–75 µm，R . hudsoni 为37–44 µm，R . guanduensis 为 44–61 µm 。Rhabdosynochus pacificus n. sp. 与该属的所有其他物种的不同之处在于具有远端扭曲的附属部分（一个亚基）。

结论

根据上述两个新种的形态测量差异，现在有效的Rhabdosynochu种数已增加到 11 个。这两个新种Rhabdosynochus代表了C. viridis上该属的第一个描述种。